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Free SSH and SFTP Tool for Windows

Windows users usually have a need to connect to Linux based systems and rely on Putty or commercially available tools. One software that system administrators use and recommend is MobaExtern – that is free and extremely powerful. If you are on a Windows platform this tool may greatly help connecting to other machines seamlessly. You […]

2015 LS-DYNA European Conference

2015 LS-DYNA European conference will be held in Wurzburg, Germany. You can get more information from here .

LS-DYNA Conference 2014

The 13th LS-DYNA ¬†conference was the largest conference which was attended by over 650 attendees¬†from around the world. You can find the papers from the conference here   Following are some pictures from the hugely successful LS-DYNA conference recently held in Dearborn, Detroit. 1. Dr. John Hallquist, President and CEO of LSTC, ¬†presenting the latest […]

Commenting LS-DYNA Keyword Blocks

A clever way to comment out blocks of keyword can be easily achieved using the *COMMENT keyword. Example: In the following example, the keyword *MAT_ELASTIC and all cards until the next keyword is commented out by simply adding a *COMMENT in front of it. *MAT_ELASTIC 1, 1.0e-9, 210.00, 0.3 *SOME_OTHER_KEYWORD …. …. to *COMMENT*MAT_ELASTIC 1, […]

Frequency Domain and Fatigue Analysis in LS-DYNA

Dr. Yun Huang and prepared an excellent package to get started in Frequency Domain and Fatigue Analysis in LS-DYNA. You can download the package here (From FTP.LSTC.COM)

Parameter NLOC in *SECTION_SHELL

NLOC value (default = 0 ) allows you to specify an offset of the reference surface from the nodal surface. Image below illustrates the significance of this value.

Cohesive Element Timestep

Cohesive material models are well suited for representing the behavior of structural and non-structural adhesives that is now increasingly used. To accommodate extreme dimensions of the element such as zero volume or near-zero volume, the timestep of the Cohesive element is based on the characteristic stiffness and mass of the element instead of the characteristic […]

Parameter DIR in DEFINE_COORDINATE_SYSTEM

In earlier versions of LS-DYNA, the axis N1-N2 was always set as the local-x but in new versions (since LS-DYNA v971), the N1-N2 vector can be configured to be either X,Y,or Z. Image below shows the influence of DIR in the local system set up.

Recommended settings for Spotwelds

When using spotwelds, there are several non-default parameters that are recommended to improve the spotweld behavior and model robustness. Following are some of the important parameters: 1. CONTACT_CONTACT/OUTSEG This parameter helps to get a list of all spotweld nodes and the parent segment information. This is helpful in earlier designs to ensure the spotweld node […]

Total Mass, Physical Mass and Added Mass

LS-DYNA reports three types of mass information for the model. The total mass and the physical mass is the same which is the mass of the model before any added mass is calculated. Added mass is the mass required to add to the nodes for all elements whose timestep is below abs(DT2MS). The effective mass […]

Air particles and relaxation when using Particle based airbag inflation

When using particle based airbag inflation method using *AIRBAG_PARTICLE, the initial air in the airbag can be modeled using control-volume approach or as particles. This is governed by the parameter IAIR. When IAIR=1, a uniform-pressure model is used to specify the initial atmospheric temperature inside the bag. When IAIR=2, one can specify the number of […]

MPP LS-DYNA Intermittent Profiling Information

During MPP LS-DYNA execution, often there is a need to know how each of the “threads” are doing in terms of overal CPU utilization. Until now, one has to wait till the job is fully finished so we can review the load-balance information from the main D3HSP file. From LS-DYNA 971 r7 onwards, there is […]

In Airbags with reference geometry (*AIRBAG_REFERENCE_GEOMETRY), when the airbag bag element in folded state is smaller or larger than the reference state, stress needs to develop. LS-DYNA suppresses these initial strains so no stresses develop to avoid bag distortion and to improve stability. This may cause the bag to deploy but its final shape may […]

Hugely Successful LS-DYNA Conference 2012

Recently held 12th LS-DYNA Conference, June 4-5 2012, was a huge success with over 680 attendees from over 21 different countries. It was great to see users from all over the world attend and present some fascinating work in LS-DYNA. The concluding talk on LS-DYNA developments and roadmap from Dr. John Hallquist and the development […]

Visualization of Triaxiality Factor in LS-PrePost

Stress Triaxiality is the ratio of Hydrostatic stress and the von-Mises stress and is known to have a great influence on the plastic deformation. You can view this factor in LS-PrePost now as shown below.

LS-DYNA Advanced Class in Detroit

Its been a while since my last post. I wanted to take the time to share that I will be teaching an LS-DYNA Class in Detroit, Michigan. You can visit Registration for more information. FEA Information will be including more information on this in its next publication.

LS-Prepost on Mac !

LS-PrePost development version 3.2 is now released for Macs. Below is a screenshot of LS-PrePost running on a MacBook Pro. You can download it Here Click to Enlarge:

Oasys 4th LS-DYNA Update Meeting in Pune and Bangalore

I will be attending the upcoming LS-DYNA Update meeting in Pune (May 3, 2011) and Bangalore (May 5, 2011). You can find more information at LS-DYNA Update meeting . If you are in Pune or Bangalore, it will be great to see you there.

Tensile failure in Low Density Foams

When modeling low-density foams, it is important to consider potential failure under tensile loading. In LS-DYNA, the most popular constitutive material model is MAT_LOW_DENSITY_FOAM (MAT_057), in which the default treatment of foams under tensile loading is linear with no failure. The Elastic Modulus (Emax) in tension is computed to be the max( max(slope of the […]

Viewing Contact Frictional Energy

When friction is enabled in contact treatment using static or dynamic fricition coefficients (FS, FD in *CONTACT), the energy dissipated due to friction can be recorded and visualized. The parameter that tells LS-DYNA to ouput the frictional energy is FRCENG in *CONTROL_CONTACT. FRCENG by default is set to 0 to ignore the recording and output […]

Hybrid LS-DYNA

With the recent growth of multi-core chips, scalibility of pure MPP LS-DYNA beyond 128 cores has shown degration due to several factors including latency and network communications. LSTC has recently developed a new code named “Hybrid LS-DYNA” that provides sustained scalibility for large number of cores and also yields digit-2-digit repeatibility when changing the number […]

Hybrid LS-DYNA

With the recent growth of multi-core chips, scalibility of pure MPP LS-DYNA beyond 128 cores has shown degration due to several factors including latency and network communications. LSTC has recently developed a new code named “Hybrid LS-DYNA” that provides sustained scalibility for large number of cores and also yields digit-2-digit repeatibility when changing the number […]

Mat224 Keyword Manual Pages

Several of you requested the manual pages for the newly developed tabulated Johnson-Cook constitutive law now labeled as MAT_224. Here are the three pages of the keyword manual. MAT224 All Pages [ Click the image to enlarge] MAT224 Page 1 [ Click the image to enlarge] MAT224 Page 2 [ Click the image to enlarge] […]

Shell Local Material Axis Definition for Orthotropic Material

Most orthotropic material rely on the parameter AOPT to define the change/update the default material axes defined by LS-DYNA. The default axis for every shell element is based on the order of the node numbers if INN=0 which is then based on N1-N2 and the cross-product of N1-N2 and N1-N4. The default material axes may […]

LS-DYNA Material Selector

Finding a good material law can sometimes be a daunting task even for experienced users. To facilitate a quick review of possible material laws for a given material criteria, a LS-DYNA Material Law Browser was created for personal use and I hope its useful for others. Please send any feedback you may have at info […]

LS-DYNA and D3VIEW helps BYU Students build PACE F1 Car

Over six months ago, two students, Rob Moncur, pursuing his MS, and Satyan Chandra, pursuing his UnderGraduate Studies, in Brigham Young University (BYU) set out on a path to build a LS-DYNA crash-analysis model of the PACE F1 car in under 8 weeks. Under the guidance of their professor, Dr. Greg Jensen, and with minimum […]

Experimental Data Management inside d3VIEW

As a simulation engineer, we always like quick access to experimental data. Over the years, with a powerful framework that was developed within d3VIEW, this is now possible to import and visualize experimental data. With a few configurations, you can further tie this with simulation data for easy overlay and comparison. This following video shows […]

Thick shells in contact

During one of my recent trips, a question was raised about how LS-DYNA treats thick shells in contact in particular if the contact would detect the surface sides. This simulation Thickshells in contact shows that LS-DYNA treats the thickshells as solids in which all external (free) surfaces are included in the contact. ERODING contact would […]

Visualizing Dynamic Relaxation Convergence

Understanding the rate of convergence when employing Explicit Dynamic Relaxation can be very useful to track model sensitivity and to solve convergence problems. d3VIEW now has support to auto-extract the convergence information after a simulation is completed. It also processes DR graphics data to identify points of divergence. Attached is a snapshot from a recent […]

Visualizing User Generated Results into LS-OPT

To view results from manual what-if studies, LS-OPT provides a great way to import these results so we can take advantage of its data visualization package. The attached image, an excerpt from the LS-OPT Manual, shows how we can do this.

Sensor Definitions in LS-DYNA

Sensors can be used to trigger entities based on certain criteria. The following image is a high-level steps involved to take advantage of sensors in LS-DYNA.

*RIGIDWALL_{DISPLAY} option

Rigidwalls are analytical representations of surfaces or volumes that are frequently used to represent stiff structures that are either stationary or in motion. Viewing of such analytical definitions in D3PLOTs were not possible for most rigidwalls. A new option in LS-DYNA named DISPLAY that can now be used to any *RIGIDWALL definitions which causes LS-DYNA […]

Several joints are available in LS-DYNA that can be defined between two rigid bodies or nodal rigid bodies. The difficult part of the joint definition from the pre-processing point of view is the creating of nodes that defines the joint axes and subsequent merging of them to the respective rigid bodies. To simlpy this problem, […]

LS-DYNA Examples Blog by Student Qui

Update The blog no longer seems to exist. I recently came across a nice blog written by QUI. It is remarkable that he is willing to share examples and his experiences in LS-DYNA. The broad spectrum of LS-DYNA applications can never be fully covered by a single blog or a small set of publications. It […]

Unloading in MAT_FABRIC (MAT_034)

This is a post by Guest Author Satish Pathy who works full time for LSTC In *MAT_FABRIC, element formulation 4 & 14 will allow you to input unloading curve for the material. Recently in a model it was noticed, that when a large compressive stress develops in the fibers, lsdyna would release some of these […]

Mass scaling for MAT_SPOTWELD elements

Deformable spotwelds modeled using beams or solids elements can invariably limit the global timestep due to its small dimensions. LS-DYNA provides two methods to scale the spotweld timestep. The first method is the well-known global mass-scaling using DT2MS in CONTROL_TIMSESTEP. When DT2MS is non-zero (usually a negative number), the density of the spotwelds are modified […]

Shell, Solid and Beam Formulations for Explicit and Implicit

Control cards are often handy to overwrite local values. A good example would be if we need all parts to use a certain element formulation THEORY which is specified in *CONTROL_SHELL.As with any global control cards that manipulate local values, the global values specified in *CONTROL keywords are used ONLY if the local values are […]

Modeling rigid bodies

LS-DYNA allows the modeling of rigid-bodies by assigning any part with the MAT_RIGID material law (MAT_020). This is by far the most easiest method available when compared with all finite element codes. When using MAT_RIGID, there are three distinct ways to model a rigid part and they are briefly explaine below. 1. Finite Element based […]

Happy New Year !

Wishing everyone a very happy new year.

Significance of IGAP Parameter in *CONTACT in Implicit Analyses

In traditional explicit analysis, there is no convergence criteria that is checked for each time step. However, in Implicit calculations, incremental displacements are evaluated such that a displacement norm and the energy norm are within a pre-defined tolerance before convergence is assumed to be obtained. This is the so-called iterative scheme in Implicit Non-Linear Analyses […]

Marsha Victory, Thank You For Your Blog Hosting Sponshorship !

I am pleased to inform that Marsha Victory has continued the sponsorship of D3VIEW blog hosting. If this blog has been of help to you, please take a moment to thank Marsha. She can be contacted at marsha at lstc dot com. Thanks very much, Marsha, for your support.

Boundary prescribed motion and Contact

When nodes are involved in both contact (penalty) and prescribed motion, contact failure is expected to occur. This is because the boundary conditions are always processed after all the contacts are handled that results in nodal accelerations being updated to enforce the boundary conditions. I will soon publish some examples to illustrate this phenomenon.

LS-OPT 4.0 is now released.

The LS-OPT Version 4.0 beta release is now available at: LS-OPT 4.0 The Presentations folder has an overview and outlook of LS-OPT. The main feature is the next generation post-processor (Viewer). Note that LS-OPT/Topology will be available later in 2009 as a separate module.