MotionSolve における接触で薄いゴムシートが必ず貫通してしまう問題について

Armstrong

現在、以下の条件で衝突解析を行っていますが、落下してきた物体が地面に固定の薄いゴムシート（10mm ）を必ず貫通してしまい困っています。どこを見直せばよいかご教示ください。

 ■ モデル条件

• 落下体：質量 1.2 kg の剛体立方体
• 自由落下高さ：0.5 m
• 接触面積：一辺 53.18 mm の正方形
• ゴムシート材性：ヤング率 27 MPa

■ Contact 接触設定

• Stiffness：K = 8000 N/mm
• Damping：40 N·s/mm
• Exponent：n = 1.0／1.5（両方試しました）
• Penetration depth (dmax)：0.1 mm
• Time step：Auto

StiffnessやDampingを大幅に変えても状況は変わらず必ず貫通してしまいます．

貫通せず止めるために，Contact 設定でどのパラメータを再調整すべきでしょうか？

また，設定を見直す箇所はありますか？

GTT Adam

Translated Using Google Translate:

I am currently performing an impact analysis under the following conditions, but I am having trouble with the falling object always penetrating the thin rubber sheet (10 mm) fixed to the ground.

Please advise me on what I should review.

■ Model conditions Falling object: Rigid cube with mass 1.2 kg Free fall height: 0.5 m Contact area: Square with sides of 53.18 mm Rubber sheet material properties: Young's modulus 27 MPa

■ Contact settings Stiffness: K = 8000 N/mm Damping: 40 N·s/mm Exponent: n = 1.0/1.5 (I tried both) Penetration depth (dmax): 0.1 mm Time step: Auto

Even if I make drastic changes to the stiffness and damping, the situation doesn't change and the ball always penetrates. Which parameters in the Contact settings should I readjust to stop the ball from penetrating? Also, are there any settings I should reconsider?

Hi @Armstrong,

I'm sorry you are having trouble with your contact simulation. Based on what I can deduce, there are a few factors you can change to improve your test:

• The distance you are dropping this small object from is incredibly large. The solver does not compute the contact until a buffer window distance is breached which is dependent on the simulation step size. If the object is outside the buffer window at a time step, then is beyond the thin object at the next time step, it is possible it is missing this buffer window entirely. Please make the contact body (10mm thin sheet) thicker or lower the simulation step size by factors of 10 until contact is realized.
• The Penetration Depth is not a parameter for maximum allowable penetration due to contact. It is the length of engagement before the maximum damping value is asserted.
• In the Contact properties, you can enable the "Find precise contact event" setting as well as the "Change simulation max step size" to improve the performance of the Contact.

However, I mocked up the following model with your provided values and those Advanced Features enabled as a test and the contact was achieved without issue. Please see the animation below:

Drop Height (5000mm):

I retried this simulation with default contact parameters and the contact still worked, however the rubber components do bounce quite a bit.

Please find the MDL attached:

motionview_contact_drop.mdl

Hope this helps!

Adam Reid