Design and additive manufacturing of architected materials with non-linear mechanical response
Tutor / director / evaluatorValdevit, Lorenzo
Document typeBachelor thesis
Rights accessRestricted access - author's decision
Most structural systems are designed to operate in their elastic regime, resulting in a linear relationship between applied loads and resulting displacements. This behavior is easy to analyze but not necessarily optimal in all situations. For example, structures that exhibit stiff response at small loads but extreme compliance above a prescribed load threshold can act as efficient isolators. Similarly, stiff structures that dissipate vast amounts of energy during cyclic loading at any given frequency are desirable for extreme damping applications. Both behaviors can be implemented in simple systems comprising negative stiffness elements, properly constrained by positive stiffness springs. Theoretical models are available, and prototypes obtained by laboriously assembling combinations of traditional springs and pre-buckled beams have verified the theoretical models. Building upon this body of knowledge, this thesis explores the applicability of additive manufacturing to realize an architected damping material with the non-linear features mentioned above. In such a design, the topology and geometry of individual cells can be tailored in order to optimize the desired global properties. Thereby, the aim of the global structure is to reach high values of stiffness and damping by stacking unit cells with a hysteresis in their response, based on the negative stiffness effect. This work presents analytical and numerical models and designs, prototypes of additively manufactured single-unit-cell and periodic samples, as well as experimental verification of their nonlinear mechanical response.