Dynamic Simulation of Soft Multimaterial 3D-Printed Objects

This article describes a 2D and 3D simulation engine that quantitatively models the statics, dynamics, and nonlinear deformation of heterogeneous soft bodies in a computationally efficient manner. There is a large body of work simulating compliant mechanisms. These normally assume small deformations with homogeneous material properties actuated with external forces. There is also a large body of research on physically based deformable objects for applications in computer graphics with the purpose of generating realistic appearances at the expense of accuracy. Here we present a simulation framework in which an object may be composed of any number of interspersed materials with varying properties (stiffness, density, Poisson's ratio, thermal expansion coefficient, and friction coefficients) to enable true heterogeneous multimaterial simulation. Collisions are handled to prevent self-penetration due to large deformation, which also allows multiple bodies to interact. A volumetric actuation method is implemented to impart motion to the structures, which opens the door to the design of novel structures, and mechanisms. The simulator was implemented efficiently such that objects with thousands of degrees of freedom can be simulated at suitable frame rates for user interaction with a single thread of a typical desktop computer. The code is written in platform agnostic C++ and is fully open source. This research opens the door to the dynamic simulation of freeform 3D multimaterial mechanisms and objects in a manner suitable for design automation.