Reaction forces are exerted by a body when an external force is being applied to it. For instance, if you’re walking on the street, there will be a resultant reaction force exerted by the street. This reaction force has two components. First, we have a vertical component to support the force from your weight. The second is a tangential component, friction. And so, from this example, it becomes apparent that those forces are only present at constrained nodes, and not free ones. This is also where Abaqus calculates reaction forces.

Let’s take a look at two ways to find and plot the reaction forces, as well as why you might choose one over the other.

Model Setup

The model below shows an explicit simulation of a rigid sphere bouncing on a trampoline. We’ve modeled the trampoline bed as well as the trampoline frame using S4 elements. As for the sphere, we’re using R3D4 elements. Lastly, we’ve modeled the springs as SPRINGA elements.

The legs of the trampoline frame are fixed in all degrees of freedom (ENCASTERED). Additionally, the bases of all seven legs of the frame are tied to a reference point using a kinematic coupling constraint. Since this is a drop test, we’ll apply an initial velocity of 5 m/s to the rigid sphere. A gif shows an animation of the simulation, with the color field set to von Mises stress.

Because the legs of the frame are constrained in all degrees of freedom, Abaqus will calculate the reaction forces there, and only there.

There are two ways of extracting the reaction force:

1. To obtain the data at better resolution with a higher sampling rate, you can request the reaction force history output at the reference point tied to the legs. You can adjust the frequency to output at higher sampling rates.
   • In Abaqus/CAE, this is done by Output > History Output Requests > Create, then choosing RF under Forces/Reactions
   • In the input file:

     *Output, history, time interval=0.0005
     
     *Node Output, nset=Set-1
     
     RF1, RF2, RF3, RM1, RM2, RM3

     (Set-1 contains the reference point mentioned earlier)

     

2. If you forget to request the history output, Abaqus, by default, outputs preselected field output variables. After step 4 (below), be sure to select the reference node tied to the legs of the trampoline frame. You can find this under the Elements/Nodes tab.

Plotting Reaction Forces Results and Discussion

To highlight the difference between the two methods of obtaining the reaction force, I’ve overlaid the reaction force from the history output as well as that from the field output in one plot. This plot shows the force on the legs of the frame obtained from the history output. The period is 0.0005 seconds, or a sampling frequency of 2000 Hz, resulting in 2000 points. Additionally, you’ll see the same force obtained at a much lower sampling frequency from the field output variable, shown in yellow.

Within the range of 0.8 s to 1 s, it is clear that the force from the history output is well sampled, while the force obtained from the field output is under-sampled and does not represent the complete behavior of the structure.

Capturing the reaction force at a high sampling rate is typically only a concern for high dynamic systems. This is not the case when using Abaqus/Standard to run static analyses. For such studies, it’s sufficient to observe the reaction force coming from the field output, as the last increment is what matters.

Conclusion

To summarize, I would advise you to always output reaction forces using the history output rather than the field output. Depending on your application, and if you want to output the reaction force at a high sampling rate, you can do this without sacrificing memory on your disk.

Bilal Abdul Halim
Application Engineer Specialist, Simulation
Computer Aided Technology

“There’s a reason why there’s an eraser on a pencil.” That’s how Dan Saperstein, CATI’s senior vice president of business systems, describes the creative, iterative process of developing a product for the real world using simulation. In the early design stages, simulation allows companies greater leeway to experiment and innovate—to design with a pencil, rather than a pen.

“Companies traditionally brought products to market through physical testing,” says Dan. “They would physically design it, build it, break it, and redesign it until it was no longer broken.” It’s a process that is both time consuming and expensive, and is also limiting in the type of tests that can be performed and the data it is possible to collect from them. With simulation, the story is different. “We’re able to bring our customer’s process to market a lot faster, allowing for better quality and better innovation. Simulation is no longer a nicety in the marketplace—it’s a necessity.”

Joe Formicola, CATI’s vice president of CAE simulation solutions, concurs. “I see simulation becoming even more of an important tool for product development. It’s becoming increasingly available because of its ease of use on the 3DEXPERIENCE Platform and the connectedness to CAD, but also because of the computational capabilities that the cloud has allowed us to have.”

If the advantages that simulation brings to an engineering firm are hard to overstate, so too are the benefits that come from working with an experienced sim team.

This was the logic CATI followed in late 2020, when they acquired Caelynx, an Ann Arbor-based team of simulation consultants specializing in the Dassault Systèmes product line of simulation software, which also includes SOLIDWORKS. By bringing on a simulation team with decades of expertise in diverse fields, CATI could better support their own customer base of SOLIDWORKS users by helping them integrate their CAD workflows to a wider range of advanced simulation tools.

However, as Joe is quick to point out, an expert simulation team is an enhancement to a company’s internal team, not a replacement. “We want our customer’s expert engineers to have expert tools. But to create these types of easy-to-use workflows that connect to CAD and are very advanced, you need people with experience who have in-depth understanding of the physics solvers, of the CAD tools, and who are used to working with customers and helping them implement these tools.”

For as impressive as all that sounds, the depth and breadth of CATI’s new simulation team can best be demonstrated by introducing the individual members. If your company needs simulation support, these are the people ready to assist you.

Meet the CATI Sim Team Leaders.

From the early days of simulation, incorporating multiphysics simulations has been a core need for engineers and designers alike. Real-world product performance is often dynamic and nonlinear in nature, with scenarios playing out in unexpected or hard-to-predict ways—at least without the aid of advanced simulation programs.

Static, dynamic, thermal, electrical, durability, and other stressors will have compounding effects that are more complex than 1 + 1 = 2. Modeling how a building might withstand the shocks of an earthquake and how an airplane might respond under turbulence both require sophisticated simulation analysis. While many software programs offer these tools separately, Abaqus’s multiphysics capabilities, both within Abaqus itself and in concert with other SIMULIA products, offer the advantage of being able to perform these simulations together from within one platform.

That means engineers can use the same CAD, FE model, load history, and element library for multiple loading scenarios, executed in sequence or simultaneously for analysis of cumulative effects.

1. Understand and defeat critical modes of failure in the battery cells of an electric vehicle.

With the increase in production of electric vehicles, we can expect to see not only more electric vehicles on the road, but more demand for batteries that meet full safety and performance parity with conventional vehicles. This makes it more urgent than ever to seek innovative solutions to all battery engineering issues.

Multiphysics simulations can not only analyze structural and impact loading in the battery assembly, but also tackle more complex scenarios like the mechanics of thermal runaway and the liquid cooling of battery packs.

2. Model the performance of implanted medical devices in the human body.

The human body is one of the most complex organisms on the planet. Over the years, life sciences simulations have become increasingly developed so that they can show how the human body functions in various conditions.

One of the most significant applications for this technology is in the development of biomedical devices, particularly implanted devices, which can have a huge impact on the health and quality of life for patients. Multiphysics simulations can show how these devices will affect the human body and how they will perform over time. They can also simulate the human body itself, as seen with Dassault Systèmes’s Living Heart Project, paving the way to new designs for pacemakers, stents, and the like. Multiphysics involving electromagnetics can also help with, for instance, analyzing heat generation from MRI in the body and implant devices.

3. Demonstrate structural integrity of a dam after an earthquake.

Large structures that are expected to last for decades must be able to withstand once-in-a-generation environmental catastrophes. (And the largest and most significant of these structures must be able to withstand even more than that.) Dams are an excellent example, both as large structures that are built to last, and structures where failures can have catastrophic consequences.

Building earthquake resistant dams is essential in many parts of the country that experience frequent geologic activity. For this, multiphysics simulations can show not only how the construction materials of the dam will respond, but the affect the earthquake will have on the waters behind the dam. Since the combination of these forces is likely to be severe, accurate modeling is crucial for public safety.

4. Simulate the effects of waves on offshore structures.

Another place where fluid and mechanical simulations coincide is on off-shore structures like pipelines or wind farms. Hydrodynamic wave loading can demonstrate how a structure will respond under a range of sea conditions, such as a large storm or a hurricane, in addition to all the mechanical, thermal, and other requirements that must be satisfied.

With more of these structures being built, and weather conditions growing more severe, multiphysics simulations will be ever more important to create resilient structures now, and to analyze the strength of structures that have already been built.

5. Model the behavior of enclosed fluids and their effects.

Enclosed gasses and liquids behave in a number of dynamic ways within an enclosed environment. Liquid inside a fuel tank under acceleration could cause significant shifts in center of gravity, resulting in highly dynamic structural effects on the attaching assembly. Likewise, in a crash scenario, an inflating airbag and a dummy could have a dynamic relationship upon collision, deviating from the expected behavior if modeled and analyzed separately.

Using multiphysics simulations, engineers can model how an airbag might behave after inflation, or how movement of liquid inside a fuel tank might affect the handling of a vehicle.

CATI can be your VAR for Abaqus multiphysics software.

When you choose to buy Abaqus software, you won’t be left trying to train your team on your own. As VARs of Dassault Systèmes software, which includes SIMULIA and Abaqus CAE, we are here to help you choose the right software solution for your engineering needs, assist in setting up an environment that will let you run the right simulations, and provide training for your engineering team.

At CATI we have spent years building a team of experts in fields ranging from FEA to CFD to life sciences to mechanical physics. Our engineers commonly hold PhDs in their field, and have published papers using results achieved from using Dassault Systèmes products such as CST Studio Suite and Abaqus CAE. Even better, our engineers work closely with each other, discussing projects and collaborating on discovering solutions to tricky problems.

This is the team that will be supporting your team as you begin to work with this multiphysics software. We can bring our knowledge and expertise to bear on your multiphysics simulation projects so that you can achieve the best results for your business and your clients. Contact us today to get started.

Here are my highlights of what’s new:

Abaqus/CAE

• You can specify the thickness (max COPEN) that determines the contacting surfaces to be tracked. 
• New Abaqus/CAE plug-in to extract portion of results and store in a smaller output database 

Abaqus/Standard

Analysis Procedures 

• New GPU acceleration of the AMS eigensolver on Windows 
• Performance improvement for element output in linear analysis procedures 
• Secondary base motion in modal transient and steady-state dynamic procedures in local or global directions  
• Trim line simulation for sheet metal forming in Abaqus/Standard 

 Analysis Techniques 

• Import enhancements 
• Importing external fields in a sequential analysis 

 Elements 

• Enhancements to composites modeling with solid elements 

 Execution 

• Creating Abaqus user subroutines in individual dynamic link libraries or shared objects 
• Enhancements for translating Nastran data to Abaqus files 
• Enhancements to the abaqus adams translator 
• Flexible body dynamics workflow enhancements 

 General Enhancements 

• Defining spatial distribution of material directions 
• Removing node limit for execution on a single computer node 

 Interactions 

• Defining initial conditions by importing results data from an output database file 
• Enhanced rotational constraint for distributing coupling 

 Materials 

• Enhanced modeling of short-fiber reinforced composites 
• Improving the accuracy in a consolidation analysis for materials with low permeability 
• LaRC05 and Hosford-Coulomb damage initiation criteria 
• Metallurgical phase transformation 

Output and Visualization 

• Requesting the Lode angle term 

Abaqus/Explicit

Analysis Procedures 

• Capacity improvements in Abaqus/Explicit 

 Analysis Techniques 

• Enhanced contact formulation for Eulerian analyses 
• Import enhancements 

 Elements 

• C3D10 element distortion control 
• Linear kinematic conversion 

 Execution 

• New architecture using a combination of MPI and threads delivers improved parallel performance of Abaqus/Explicit 

 General Enhancements 

• Defining spatial distribution of material directions 

 Interactions 

• Defining initial conditions by importing results data from an output database file 
• Enhanced hard contact for general contact in Abaqus/Explicit 
• Evolving feature edge criteria with default angle thresholds 

 Materials 

• LaRC05 and Hosford-Coulomb damage initiation criteria 

 Output and Visualization 

• New contact field output CNAREA (node contact area) and CFRICWORK (nodal frictional work)  
• Requesting the Lode angle term 

Tosca Structure

• New Milling Constraint for topology optimization
• Faster evaluation of design response groups for Abaqus based optimizations
• Plastic strain as design response for Topology optimization
• Rotational symmetry in sensitivity-based shape optimizations
  

For the complete Abaqus Unified FEA 2021 release notes, follow the steps outlined here in our Support & Tools section.

As electric vehicles take over a larger share of the automotive market, OEMs and suppliers alike need to make use of every tool at their disposal to improve the performance of their vehicles. At present, no tool is more essential than CAE simulation when it comes to helping manufacturers test the design of EM components and how they contribute to the structure, efficiency, and performance of a vehicle.

While a lot of attention is often focused on battery performance in EVs, the electric drivetrain also presents completely new engineering challenges that require extensive simulation in order to understand how interconnecting systems affect each other. From our experience working in the automotive industry, we have identified six key areas where simulation helps EV engineers improve drivetrain performance. Let’s take a closer look.

1. NVH

Trust the Drive – Electric Drive Noise and Vibration Analysis
WATCH THE WEBINAR NOW

2. Electric Motor Performance

Electric vehicles have typically lagged behind those with internal combustion engines (ICEs) in terms of power and performance. This has been a barrier to wider adoption, as improvements in motor and transmission performance have come at a tradeoff to battery longevity. However, newer EV technologies have increased the efficiency of electric powertrains, allowing them to compete with and even outperform their ICE counterparts.

Multiphysics simulations have been integral to these improvements, and can help automotive manufacturers develop even better designs. This can be particularly important in optimizing motor efficiencies with gear ratios, to improve performance on highways or during uphill driving.

3. Thermal Management

Electric Drive Engineering
WATCH THE WEBINAR NOW

4. Lubrication

Electric vehicles require different lubricants than ICEs. Without fossil fuels and with fewer moving parts, these systems run cleaner, meaning the engine oils will collect fewer contaminants over time from burning fuel. However, EV motors operate at very high speeds, and still require both oil and coolant. And, while EV transmissions are different from ICEs, they do still require lubrication for the gear reducer.

Thus far, there is no one solution to which lubricants should be used for different EV transmissions. While some manufacturers use traditional transmission fluid, others are relying on grease bearings with oil lubricants. CFD simulation can help engineers understand which lubricants work best based on their design choices.

5. New Materials

WLTP and Lightweighting – Lighten the Burden of WLTP
WATCH THE WEBINAR NOW

6. Durability

The reputations of automotive manufacturers are made or broken on the reliability and longevity of their products. Premature failure of components leads to lost trust among consumers, as well as extra expenses for manufacturers in case of a large recall.

Using CAE simulation, engineers can create models to run fatigue tests and predict failure conditions for every component in the EV driveline. These simulations can help manufacturers determine repair schedules and write better warrantees for their vehicles.

CATI can support your simulation needs for electric vehicle drivetrains.

CATI offers CAE simulation support for OEMs and suppliers in two key ways. First, we are value-added resellers (VARs) of Dassault Systèmes software, including Abaqus, CST Studio Suite, CATIA, and SIMULIA. For manufacturers who hope to expand their CAE departments we offer support for using this software to set up custom workflows.

Second, as CAE and FEA consultants, we bring our multidisciplinary expertise to the table, helping our clients find solutions to complex problems. We can perform CAE simulations for our clients, increasing the capabilities for those who do not have CAE engineers on staff, and expanding the capacity for those who need extra assistance during peak production times.

If you are looking for a CAE partner to help test designs for EV components, contact us. We would love an opportunity to contribute our automotive expertise to your project.

Simulation is becoming increasingly integral to engineering departments across industries. The growing capabilities of simulation software have allowed engineering departments to integrate CAE processes into their research and development workflows at every stage, so that new designs can be tested at every point, from initial concept to final product validation.

The increased utility of simulation has led to a growing demand for powerful simulation software that is accessible to businesses of all sizes. In response, Dassault Systèmes has made their 3DEXPERIENCE platform available on private cloud infrastructure, allowing businesses greater flexibility in how they use the software. For engineers who use Abaqus—or those intending to purchase FEA simulation software—the new cloud platform offers an excellent solution to their needs.

Whether used as the primary simulation platform, or as an auxiliary for businesses that need to scale their capabilities, Abaqus’s new cloud service is an important tool that will help engineering teams around the world respond with increased flexibility to simulation demands. Here are the top six advantages Abaqus cloud brings to engineering departments.

1. Access High-Performance Computing (HPC) capabilities without the hardware investment.

2. No need to manage or maintain hardware assets.

Cloud computing saves businesses the costs of having to upgrade their hardware, but it also saves them significant expenses related to networking, housing, and maintaining these computing clusters. These costs include IT staff to help with networking issues, and special, climate-controlled storing rooms to keep the computers cool. You will even keep your energy costs down!

3. No extensive setup and installation time, because 3DEXPERIENCE is already configured.

A secondary concern to purchasing new hardware is that doing so also requires setup time for each instance of Abaqus which needs to be installed and configured. Using Abaqus on the cloud doesn’t demand the same resources, because it’s already set up on the 3DEXPERIENCE platform. Businesses can be up and running in an hour, making it easier for them to scale up their simulation capabilities if needed.

4. Abaqus on the cloud integrates easily with your current workflows.

Another drawback companies face as they incorporate new systems is that even small differences in a user interface or operating system can force changes in a workflow that lower efficiency while users learn the new system. The more drastic the change, the more the new system can disrupt a workflow, leading to frustration, errors, and delays.

From a user experience, running Abaqus on the cloud integrates seamlessly into existing workflows.  Users continue to use their preprocessor of choice to create their Abaqus models.  Then they upload their input deck to the 3DEXPERIENCE platform, submit the job on the cloud, and download results for local postprocessing.

5. On-demand licensing helps companies manage surges in simulation needs.

Businesses of every size experience fluctuations in demand for both their products and their simulation software. During peak times, they may find that they don’t have enough software licenses to handle the workload, while in slow times, they may feel they are paying for more than they use.

Cloud licensing offers a new purchasing model where users can choose to run simulations using the traditional token model or by purchasing on-demand credits. Because running Abaqus on the cloud means users don’t have to download software or upgrade the hardware of their local computing systems, it is easy for companies to bring in additional support for the busy season without having to purchase excess licenses.

6. Securely store Abaqus files where they can be accessed anytime and anywhere.

As more and more businesses move to remote work environments and smaller, global offices, the logistics behind access to simulation files become more complex. Fortunately, simulations stored in the cloud can be accessed from any location, with results that can be downloaded for local post-processing, viewed through the browser-based 3DPLAY application, or through the Simulation Results Analyst software, which allows for more detailed performance visualizations.

As a Value-Added Reseller (VAR) of Abaqus software, we can provide all the technical assistance you need.

1. Turn off multithreading

Hyperthreading benchmark on our machines (your results may differ)

2. Stay up-to-date on your software

A new version of Abaqus may seem like a complication to a system that’s already working, but it’s always an opportunity to find performance improvements, as such improvements are a regular refrain in the yearly release notes. Moreover, you can have multiple versions of Abaqus installed at once, so your old versions are not at risk. What you stand to gain is:

• Flat-out speed increases
• Reduced restrictions of various functionalities
• New features and models (like element formulations and material behaviors)
• Bug fixes
• And more

Read the Abaqus release notes at least on a yearly basis (ideally, the mid-year updates as well) to make sure you’re not leaving anything on the table (especially since you’re already paying for it).

3. Control your internal tetramesh

How to adjust internal tet size in Abaqus/CAE

4. Start using general contact, even in Abaqus/Standard

If you’ve been using Abaqus for a while, you may be very used to defining contact pairs for all your interactions. But it’s a pain in the butt — it takes forever, and it can get hard to manage if there’s a lot of them. The good news, is that general contact is now an excellent choice not just for Abaqus/Explicit, but also for Abaqus/Standard. It is faster to set up, and it converges more easily. If you choose automatic “all exterior” detection, just be sure to account for any preexisting penetrations, component misfits, or unintended emergent contact behavior mid-scenario.

5. Understand what controls stable time increments in Abaqus/Explicit

In Explicit, the speed of your run is governed by the length of your model’s “stable time increment”. Here’s what affects that:

• Element size: larger elements, longer stable increment
• Material density: higher density, longer stable increment
• Material stiffness: lower stiffness, longer stable increment

The most important items is the first — element size. If you’re mindful of your mesh, you can do your best to eliminate small elements (which may involve some engineering judgment) and enjoy a faster solve. You may or may not be able to control the latter two items, but you can know what to expect. You can also use mass scaling features to artificially mitigate the adverse effects of small elements. More on this in the webinar.

Product Enhancement Overview: Abaqus 2020 FD03 (FP.2022)

General Enhancements

• In an Abaqus/Standard analysis you can now use more than 16 million nodes on a single computer node – 2020 FD02 (FP.2014).
• The Abaqus Python version is upgraded to 2.7.15. Numpy is now at version 1.15.4. The SciPy and SymPy packages are now included with Abaqus Python.

Abaqus/CAE

Enhanced Functionality

• Material enhancements – 2020 FD01 (FP.2007):
  • For the creep model, you can specify the time type (total or creep) and the Anand, Darveaux, and double power laws.
  • For the cap plasticity model, you can specify the time type (total or creep) and the power and time power laws.
  • For the viscous model, you can specify the time type (total or creep) and the Anand, Darveaux, double power, power, and time power laws.
  • For the Drucker-Prager creep model, you can specify the time type (total or creep) and the power and time power laws.
  • For the plastic model, you can scale the yield stress and include the static recovery term with the nonlinear isotropic/kinematic hardening model.
  • For the gap flow model, you can select the Bingham plastic or Herschel-Bulkley type to specify how you want to define the flow parameters.
  • For the user material model, you can indicate that user subroutine VUMAT contains the effective modulus for an Abaqus/Explicit analysis and specify the hybrid formulation for hybrid elements in an Abaqus/Standard analysis.
• General contact enhancements – 2020 FD01 (FP.2007):
  • For general contact in Abaqus/Standard, you can specify secondary feature edge criteria for surface property assignments and control the smoothness of the surface-to-surface formulation upon sliding for specific interactions and control the edge-to-edge contact formulations.
  • For general contact in Abaqus/Explicit, you can specify secondary feature edge criteria and apply feature edge criteria statically or dynamically for surface property assignments and choose which sides of double-sided elements will be considered for node-to-face or Eulerian-Lagrangian contact with another surface for contact formulation.
• Mechanical contact properties enhancements – 2020 FD01 (FP.2007):
  • You can specify the thickness that determines the contacting surfaces to be tracked.
  • You can define the surface interaction model in user subroutine UINTER in an Abaqus/Standard analysis or user subroutine VUINTER or VUINTERACTION in an Abaqus/Explicit analysis.
  • For a surface interaction model defined in a user subroutine, you can specify the number of state-dependent variables and the number of property values that are required.
  • In an Abaqus/Standard analysis with user subroutine UINTER, you can use unsymmetric equation solution procedures.
• You can now choose the position where selected field output values are written – 2020 FD01 (FP.2007).
• When partitioning cells by extrude/sweep of edges, the selected edges no longer need to be connected to each other.
• You can now directly import Solidworks part and assembly files as parts in Abaqus/CAE.
• You can choose local coordinate systems for displaying the results of queries such as points and distances.
• You can renumber nodes and elements on parts by selecting from dependent instances in the assembly context.
• The shear panel element type (SHEAR4) can now be assigned in the Mesh module.
• Support for tensile failure plastic material suboption is now available.
• Material test data evaluation is now supported for hyperfoam material data.
• Abaqus/CAE now supports contact initialization data and assignment for Abaqus/Explicit.
• You can now create a cluster areas geometric restriction for sensitivity-based topology optimization in Abaqus/CAE.
• Synchronization of animations across multiple viewports is now controlled through linked viewports and the Linked Viewports Manager.

Modeling

Enhanced Functionality

• You can now specify a spatial distribution by importing data from a user-defined output database (.sim) file – 2020 FD01 (FP.2007).

Analysis

New Functionality

• You can now perform a one-step inverse analysis in Abaqus/Standard to obtain the initial shape of a sheet metal part given its final (deformed) configuration and a reference blank surface to which the initial configuration must conform – 2020 FD03 (FP.2022).
• A pattern-based special-purpose technique is now available for powder bed-type additive manufacturing processes – 2020 FD01 (FP.2007).
• Fluid exchange based on the surfaces of failed elements is now available in Abaqus/Explicit – 2020 FD01 (FP.2007).
• You can now specify interface nodes in the matrix generation procedure and use them to include generated matrices in the model in the matrix usage analysis – 2020 FD01 (FP.2007).

Enhanced Functionality

• The adaptive mesh refinement feature now allows you to improve the contact for Eulerian-Lagrangian contact interfaces – 2020 FD03 (FP.2022).
• The AMS eigensolver is enhanced to support GPU acceleration on Windows platforms. The AMS eigensolver can use compute-capable GPUs on Windows platforms to reduce the run time for frequency extraction analyses – 2020 FD02 (FP.2014).
• You can now include the temperature degree of freedom in a crack propagation analysis using the extended finite element method (XFEM) – 2020 FD02 (FP.2014).
• You can now transfer model data and results of elements sets or part instances mutliple times from an Abaqus/Standard analysis to an Abaqus/Standard analysis – 2020 FD02 (FP.2014).
• You can import an external field to define distributions, initial conditions, and history-dependent fields – 2020 FD02 (FP.2014).
• The size of the models that Abaqus/Explicit can solve is increased significantly with this release – 2020 FD01 (FP.2007).
• The iterative linear equation solver is enhanced to support modeling features with Lagrange multipliers, such as hybrid elements, connector elements, distributing couplings, and hard contact – 2020 FD01 (FP.2007).
• New naming conventions and a change for volume fraction thresholds are implemented in the special-purpose techniques for additive manufacturing – 2020 FD01 (FP.2007).

Materials

New Functionality

• The LaRC05 and Hosford-Coulomb damage initiation criteria are now available in Abaqus/Standard – 2020 FD02 (FP.2014).
• You can now model metallurgical phase transformation during additive manufacturing processes or heat treatment processes – 2020 FD01 (FP.2007).

Enhanced Functionality

• A local stabilized method involving pressure projections into the strain space is now available to eliminate spurious oscillations in a consolidation analysis – 2020 FD02 (FP.2014).
• You can define the bulk and shear modulus in user subroutine VUMAT. The bulk and shear modulus are used to compute the stable time incrment in Abaqus/Explicit. Element information such as element number, integration point, section point, and layer number are passed in to user subroutine VUMAT.

Elements

New Functionality

• You can now use linear kinematic conversion in Abaqus/Explicit to improve simulation robustness – 2020 FD01 (FP.2007).
• Coupled temperature-displacement cohesive elements (COH2D4T, COH3D6T, COH3D8T, and COHAX4T) can be used in a fully coupled thermal procedure. You can define the thermal interaction constitutive behavior of the cohesive elements.
• Coupled temperature-pore pressure cohesive elements (COD2D4PT, COD3D6PT, COD3D8PT, and CODAX4PT) can be used in soils procedures. You can define the fluid constitutive behavior of the cohesive elements. You can also define a gap fluid heat convection behavior.

Enhanced Functionality

• You can now use distributions to specify layer thicknesses for composite solid elements – 2020 FD02 (FP.2014).

Interactions

Enhanced Functionality

• To improve robustness, Abaqus/Standard considers the rotational degrees of freedom of cloud nodes in the rotational constraints of distributing couplings by default – 2020 FD01 (FP.2007).
• Dynamic feature edge criteria are used when you specify that all feature edges for a contact surface should be activated – 2020 FD01 (FP.2007).
• The new dynamic memory management approach for solid erosion problems often results in dramatic memory reduction and 10% reduction in simulation run time – 2020 FD01 (FP.2007).

Prescribed Conditions

Enhanced Functionality

• You can now define initial predefined field variables by importing field data from an output database (.sim) file – 2020 FD02 (FP.2014).
• You can now specify initial conditions by importing data from a user-defined output database (.sim) file – 2020 FD01 (FP.2007).

Execution

New Functionality

• Parallel execution of Abaqus/Explicit is now available in hybrid mode using a combination of MPI and threads – 2020 FD03 (FP.2022).
• The new abaqus fromsimpack translator reads Simpack matrix data from a binary Flexible Body Interface (FBI) file and creates equivalent matrix data in an Abaqus SIM file – 2020 FD01 (FP.2007).

Enhanced Functionality

• Flexible body dynamics workflow enhancements – 2020 FD01 (FP.2007):
  • The new FORMULATION parameter for the *FLEXIBLE BODY option allows you to generate different versions of the flexible body for the AVL EXCITE^TM flexible body dynamics solver from AVL LIST GmbH or the flexible body for the ADAMS^TM flexible body dynamics solver from MSC.Software Corporation.
  • You can create an EXCITE binary (.exb) file for the EXCITE multibody dynamics solver as part of an Abaqus/Standard analysis.
  • The abaqus toexcite translator includes additional command line options. You can use the hide_mesh command line option to avoid writing the element nodes, connectivity, materials, and properties to the EXCITE binary file. You can use the recovery_matrix command line option to write the recovery matrix to the same EXCITE binary file as the other data or to a separate EXCITE binary file or to specify that the recovery matrix is not written.
  • For the abaqus substructurerecover utility, you can specify the node set names and the element set names for results output to help reduce the amount of output and the output database size for large-scale analyses.
• Enhancements for the abaqus fromnastran translator – 2020 FD01 (FP.2007):
  • The new cshear command line option controls whether CSHEAR elements are translated to Abaqus SHEAR4 elements or to user elements.
  • Translation time is significantly reduced for large models containing millions of composite shell elements.
  • Thermal expansion coefficients for RBE2 elements are translated to the ALPHA parameter on the *KINEMATIC and *KINEMATIC COUPLING options.
  • The global structural damping coefficient PARAM,G is translated to the *GLOBAL DAMPING option even if the damping coefficient is negative.
  • When translating Nastran DMIGs to matrix data in a SIM file, the translator automatically creates a second Abaqus input file that references that SIM file and creates an Abaqus substructure that can be used in downstream analyses.

Output

Enhanced Functionality

• You can now request the Lode angle term output at an element material point – 2020 FD02 (FP.2014).

User Subroutines

New Functionality

• You can now call utility routine GETPHYSICALCONSTANT from any Abaqus/Standard user subroutine to obtain values of physical constants defined in an Abaqus/Standard analysis – 2020 FD01 (FP.2007).

Visit the 3ds.com website to see these release notes (may require login).

Need guidance with the update?  Feel free to contact us for help!

Computer-aided engineering (CAE) has improved design and development processes in industries as diverse as aerospace, green energy, and high-tech devices. However, nowhere does CAE have a more direct impact on quality of life than in the life sciences.

During my time as a graduate student, postdoctoral researcher, and CAE simulation engineer, I have had numerous opportunities to use finite element analysis (FEA) along with multibody dynamics (MBD) solutions in life science applications. It can be used to guide designers, doctors, and engineers as they search for solutions to human problems. As I will show in this article, when advanced simulation technology is combined with the right research, it can improve comfort, reduce injury, and even save lives.

1. Consumer goods.

Consumer Goods Example 1: Foam Bed Optimization

We worked with one of our clients to optimize the foam density for a mattress. In this study, we used Isight’s built-in nonlinear sequential quadratic programming algorithm to determine the optimum structural stiffness of the foam, with the goal of creating a mattress that would provide greater comfort and more restful sleep for buyers.

Consumer Goods Example 2: Insole Study

We were looking for ways to predict stress at the interface between foot and shoe (i.e., plantar stress) which is known to play an important role in the development of foot ulcers in diabetic patients. Our task was to study the effect of insole-to-midsole heel height on the plantar stress using a finite element (FE) model in order to find the best ratio of height between the two, with the goal of identifying the optimum thickness for each.

We developed a nonlinear, axisymmetric, two-dimensional model of a human heel-shoe in Abaqus/CAE, and assigned a nonlinear foam material to the insole and midsole geometries. We changed the insole and midsole thickness accordingly using Isight, while we estimated the plantar stress by measuring the predicted maximum contact pressure between the heel and the insole to find out which iteration provided minimum stress.

Using similar methodologies, we could apply these tools to identify the key performance indicators for a variety of consumer good applications, with the ability to obtain analytical output quantities from simulation.

2. Athletic and military training programs.

FEA simulations aren’t only used for product design. In fact, because the models are designed to simulate the human body, they can be used to understand the effect of training programs or lifestyle habits on physical fitness. These include simulations that measure the influences of repetitive movements on the body, or how bone and soft tissue might be strained or strengthened under certain conditions.

Training Example 1: Exercise Machine Linkage

Many people turn to exercise machines as a central part of their physical fitness routine. On a recent project, we worked with a client to generate a design for a fitness machine that was lighter, provided increased stiffness performance, and felt more fluid to the user (i.e. reduced rotational inertia effects). Our optimization approach, using Tosca Structure, was specifically tailored to the design goals associated with the linkage. After mastering the optimized (organic) shape in CAD, the design was validated by FEA to confirm the final geometry.

Training Example 2: Load Carriage on Tibia Bone Strength

As part of my doctoral research I co-authored a study examining the influences of load carriage and physical activity on tibia bone strength. This project was designed to address a problem in the military, where new recruits had a high incidence of tibia stress factors. We compared recreational basketball players to recreational runners by having each carry loads of increasing weight. We then used a combination of subject-specific multibody musculoskeletal simulations and an FE model of the tibial bone to measure bone strain and the rate of strain. The results of this study showed that the varied, multidirectional training of the basketball players make them more resilient to load bearing than that of the recreational runners.

While this study had applications for the military, similar studies could also be applied to athletic programs. In elite sports programs, where an injured player can cost a league millions of dollars in lost talent, simulations that can identify more effective training regimens can save athletic programs financially, while also leading to healthier athletes.

These examples illustrate how FEA simulations could be used in similar applications, such as physiotherapy, to help doctors and physical trainers find more effective treatments for patients as they recover from an injury.

3. Medical device companies.

Medical devices are perhaps the largest group of possible applications for life sciences simulation. This group comprises external devices, such as braces or prosthetics, implanted devices such as heart monitors or artificial hips, and medical equipment, such as the cardiopulmonary bypass pumps used in open heart surgery.

Medical Device Example 1: Wheelchair and Hospital Chair Drop Test

Using a detailed FE model during a drop test simulation, we were able to optimize the strength and structural weight of a wheelchair’s design. We ran a similar study on a hospital chair. We built a detailed FE model of the hospital chair, then correlated it to the physical test to evaluate any design improvements suggested by the engineering team.

Medical Device Example 2: EMS Cot Performance Load Fastener

We worked with the design team of an OEM for EMS cots to perform front, side, rear, and top crash test simulations using Abaqus Unified FEA. We focused on the locking mechanism of the cot to the ambulance, using the analysis to drive design changes and enhancements. These included an optimization of the effort of the current carry over components on the cot to try to find lightweight solutions with enhanced load carrying capabilities, as well as FE models of a redesigned cot for future development.

Medical Device Example 3: Hospital Bed Comfort Design

For this project, we partnered with a hospital bed manufacturer to design pneumatic bags that would reduce bed sores and enhance patient comfort. We did this, again, using Abaqus Unified FEA for highly nonlinear structural simulation of soft materials in high deformation.

Medical Device Example 4: Blood Flow Simulation

In this project, we simulated blood flow paths through two different pipe assembly configurations for transfusion machines and blood platelet separators. Because poor recirculation can lead to clotting, it was our goal to find a configuration that would reduce undesired flows and turbulence. By performing an A/B study for each assembly we compared the predicted pressure, turbulence energy, and velocity, as experienced by the blood flow. Our simulations were able to demonstrate which configuration provided a clean laminar flow with minimum turbulence.

In each of these cases, FE simulations helped design safer devices that were easier for medical workers to use or led to increased comfort and improved health for patients. This intersection of product design and life sciences illustrates the many ways CAE can be used to improve patient outcomes.

4. Advanced research funded by hospitals or universities.

Many of the applications listed above are areas in which FEA is regularly being used to advance product development, improve health, and reduce injury. The progress already made with this research demonstrates the value of FEA alone or combined with other solutions in aiding medical research. It also highlights untapped areas of research that will benefit from advanced CAE simulations.

Advanced Research Example 1: Dental Implants

In a collaborative project with the University of Michigan, we used CAE simulations to find an optimum tightening torque for a dental implant design. We also predicted the adhesive strength using a FE model at bone/crown interfaces.

Advanced Research Example 2: Knee Biomechanics

During my postdoctoral research, I worked directly with surgeons using simulations of knee biomechanics in an MBD framework environment to help doctors determine the correct amount of external rotation of the femoral component required during TKA. Our ability to isolate bone shapes and ligaments through computational models helped us deliver better outcomes to patients and revealed a potential new surgical technique.

While these examples represent our project capabilities, new simulation tools are expanding the possibilities of this field. Recently, Dassault Systèmes collaborated with the FDA on a five-year project to create a model of a human heart. The Living Heart Project advances the cutting edge of medical research, with the potential to deliver new tools to physicians and surgeons as they plan medical treatments. Hospitals and research groups need more than access to these simulations—they need experts who can help them apply these advanced engineering solutions to their research.

Our engineering team has direct experience working on these projects.

As a field, life sciences poses both a complex subject for FEA simulation, and an exciting opportunity for advances that could have a significant impact on the health, comfort, and quality of life for people around the globe. Researchers, engineers, and product designers have access to powerful software that can simulate the bone and soft tissue of the human body, but understanding the intersection of human biology and engineering technology requires a new skillset—one that we’ve has been building for years.

We have always prided ourselves on the strength of our team. The engineers who work here possess expertise not only in creating and running complex simulations with CAE software, but also the experience of working in hospitals and with medical research teams. This allows us to undertake high-level life science projects for any number of applications.

If you are looking for an FEA partner to help you develop simulations for use cases in the life sciences field—large or small—contact us. We can discuss them with you and help you find a solution.

Getting Consistent Units: A Helpful Table

Abaqus has no built-in system of units. Therefore, before starting to define any model, we have to decide which system of units will be used. For the analysis results to be accurate or meaningful, all input data must be specified in consistent units. A system is consistent when the derived units (force, stress, energy, power) are correctly expressed in terms of the chosen base units (length, mass, time, temperature). Some common systems of consistent units are shown in the table below (source in manual).

Inch Issues: Blob? Slinch? Slugette? Snail?

Working in US (inch) units can be a real headache, and two of the most confusing properties are mass and density.  Mass and density are often given in the form of lbm and lbm/in³, respectively, and therefore must be converted to the form of lbf s²/in and lbf s²/in⁴.

Here are the conversion formulae:

Figure 1: Mass conversion: lbm to lbf s²/in

Figure 2: Density conversion: lbm/in³ to lbf s²/in⁴

Just Give Me Quick Conversions!

Our technical manager, Carl Osterwisch, has created a very useful FEA unit conversion tool.  It will take your base units of choice (length, mass, time, and temperature) and give you consistent derived units (force, stress, energy, and power).  The calculator will also take units of any system and convert them into your system.  Extremely handy.