Gokhale, V., Marko, C., Alam, T., Chaudhari, P. et al., "Design of an Advanced Layered Composite for Energy Dissipation using a 3D-Lattice of Micro Compliant Mechanism," SAE Technical Paper 2016-01-1538, 2016, doi:10.4271/2016-01-1538.
This work introduces a new Advanced Layered Composite (ALC) design that redirects impact load through the action of a lattice of 3D printed micro-compliant mechanisms. The first layer directly comes in contact with the impacting body and its function is to prevent an intrusion of the impacting body and uniformly distribute the impact forces over a large area. This layer can be made from fiber woven composites imbibed in the polymer matrix or from metals. The third layer is to serve a purpose of establishing contact between the protective structure and body to be protected. It can be a cushioning material or a hard metal depending on the application. The second layer is a compliant buffer zone (CBZ) which is sandwiched between two other layers and it is responsible for the dampening of most of the impact energy. The compliant buffer zone, comprised by the lattice of micro-compliant mechanism, is designed using topology optimization to dynamically respond by distributing localized impact in the normal direction into a distributed load in the radial direction (perpendicular to the normal direction). The compliant buffer zone depicts a large radial deformation in the middle but not on the surface, which only moves in the normal direction. The effect is a significant reduction of the interfacial shear stress with two adjacent layered phases. A low interfacial shear stress translates into a reduced delamination. The ALC’s response to the impact is tested by using dynamic finite element analysis. The proposed ALC design is intended to be used for the design of protective devices such as helmets and crashworthy components in vehicle structures.