Durability of 3D Printed Elastomer Structures

Abstract

One of the key differences between 3D printing (additive manufacturing) and conventional manufacturing is the ability of 3D printing processes to create complex structures containing open spaces, often lattice-like in nature. Such a 3D printed elastomer part can have overall loading stresses that are relatively modest and unidirectional, but these conditions can translate into much higher stress, multiaxial conditions within the struts of the lattice structure. Multiaxial load cases, crack closure considerations, and other complexities that arise in lattice designs make it impossible to predict fatigue behavior using simplistic approaches such as Wohler / stress(S)-lifetime(N) curves. This presentation will highlight how these complexities can be readily handled using the microscopic damage integration and critical plane analysis capabilities of the Endurica CL elastomer fatigue solver for finite element analysis to predict when and where cracks will show up in the structure. Cracks in an elastomer start out as microscopic precursors that grow due to applied cyclic loading according to a characteristic crack growth rate law for the material. The crack precursors – also called intrinsic defects or flaws – are especially important to pay attention to in the additive manufacturing of products in which voids or defects can be introduced by the printing process. We will demonstrate the sensitivity of fatigue lifetime to crack precursor size, considering both surface defects and internal defects in a lattice-type geometry.

About the Speaker

Dr. Will Mars is the founder and president of Endurica LLC.
He is an international leader in the failure mechanics of rubber.
He is a past editor of the journal Rubber Chemistry & Technology, and of Tire Science & Technology.

He has more than 25 years’ experience developing testing and simulation methods in the rubber industry. Dr. Mars’ professional activity has focused generally on applying experimental and computational mechanics in pursuit of better-performing rubber products.

Dr. Mars earned his Honors BSME with Polymer Specialization at the University of Akron, and his MS and Ph.D. degrees at the University of Toledo.