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…
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.
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…
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…
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…
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…
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…
My son’s, who is in 3rd grade, rendition of how we may be writing in the future …..
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.
