Making a meaningful impact: modelling simultaneous frictional collisions in spatial multibody systems

Area of Science:

• Multibody Dynamics
• Computational Mechanics
• Contact Mechanics

Background:

• Current instantaneous impact models lack accuracy for simultaneous impacts in multibody systems.
• Existing models often violate physical principles, leading to errors in simulations.
• Compliant contact models offer accuracy but are computationally expensive.

Purpose of the Study:

• To develop a computationally efficient impact model that maintains accuracy for complex collision scenarios.
• To bridge the gap between the speed of instantaneous methods and the precision of compliant contact models.
• To extend the applicability of instantaneous impact models to high-accuracy scientific and engineering domains.

Main Methods:

• A new impact model resolving collisions into compression and expansion phases with sliding and rolling intervals.
• Utilizing constrained optimization to compute incremental impulses respecting physical laws.
• Implementing the mathematical model and algorithms within the Simbody C++ library.

Main Results:

• The new model accurately replicates the behavior of detailed compliant contact models.
• Achieves over 20 times speedup compared to integrating through collisions with compliant models.
• Demonstrates effectiveness in simulations involving materials of various stiffnesses.

Conclusions:

• The developed instantaneous impact model offers a significant advancement in simulating multibody system collisions.
• Enables accurate and efficient analysis for applications previously requiring computationally intensive compliant contact models.
• Provides an open-source implementation in Simbody, facilitating wider adoption in biomechanics and robotics.