Article Number: 112 | VC6 | VC5 | VC4 | VC3 | Post Date: May 4, 2024 | Updated: May 4, 2024

How can I simulate an object, such as a barrier or post, breaking during impact?

To simulate an object breaking, you should utilize the various joints offered in Virtual CRASH. This will allow you to create a breakable composite object that can separate based on the specific breaking criteria you choose to apply. A similar workflow to that described below was used to create this video.

Before proceeding, we strongly recommend you review the following posts related to the use of joints:

https://www.vcrashusa.com/blog/2018/6/7/building-complex-systems-with-joint-tools

https://www.vcrashusa.com/blog/2018/11/8/restraining-objects

https://www.vcrashusa.com/blog/2016/7/3/making-rotating-assemblies-with-a-hinge-joint

https://www.vcrashusa.com/kb-vc-article95

https://www.vcrashusa.com/kb-vc3-article16

https://www.vcrashusa.com/blog/2020/1/22/creating-bicycle-and-motorcycle-crash-simulations-with-the-path-animation-tool

In the following example, we will simulate a post being struck by the front end of a car, focusing on breaking the top of the post. We begin by creating a cylinder and raising it above the terrain to represent the top portion of the post.

Next, we clone the upper cylinder to create the base and lower the clone along the z-axis to align with the terrain mesh.

We switch to [F3] and use the resize grips to help line up the upper portion of the lower post with the lower portion of the upper post.

Next, we convert the lower cylinder to a terrain object.

Next, we convert the upper post to a rigid body object. Set the weight as needed in the upper post’s “mass properties” menu.

Next we select the spherical joint tool.

Connect the upper to lower post by hovering over the upper post, hold+left-click and drag to lower post and release. As usual, right-click to terminate the joint command.

Switch joint to “Parent Space” mode to reposition it as needed relative to the two connected objects.

Using large values for spring and damping under “fix orientation” we can hold the two connected objects together in a stable configurations. Check “disable before breaking” to prevent the upper and lower posts from exchanging contact interactions while held together by the spherical joint.

Finally, we set our breaking conditions. Here we break the joint connection at the moment of impact. Note, as recommended in this post https://www.vcrashusa.com/kb-vc-article94, we enable Kudlich-Slibar for the narrow object impact. Note, if we needed the lower post to also break away from the ground, then we would set it as a rigid body object rather than a terrain object. The lower post can then be connected to both the upper post and the (unfrozen) terrain via spherical joints.