Flexural behavior of additively manufactured sheet-based minimal surface periodic, stochastic and spinodoid latticed-beams
摘要
Beams are an integral component of a wide range of engineering structures. However, the combined high structural weight and low damage tolerance, particularly due to the inability to control crack propagation once initiated, remain a challenge. These limitations can be mitigated through latticing of structural beams, especially those derived from Triply Periodic Minimal Surfaces (TPMSs), which offer the potential to disrupt crack continuity by effectively transmitting stresses and enabling crack deflection or jumps, and thus delay structural failure. In TPMS-lattice beams subjected to three-point bending (3 PB), stress concentrations typically develop along well-defined planes, causing cracks to propagate along symmetrical lines or mechanically weak directions inherent to the periodic unit cell network. This often results in abrupt and brittle failure under bending loads. To address this, the present work proposes the introduction of lattice-topological stochasticity and spatial heterogeneity by randomizing the local orientation and relative density distribution of the minimal surface-based sheets. The study focuses on two design approaches: stochastic sheet-based MS-lattice and Gaussian Random Field (GRF)-lattice beam designs, aiming at enhancing the damage tolerance and control failure mechanisms in latticed-beams. The effects of control points (5–1000), relative densities (20–50%) and cell sizes (1–2.5 cm) across five random realizations were examined for 16 × 4 × 4 cm3 3 PB latticed-beams to determine relationships between these parameters and flexural properties. Our findings show that TPMS-based latticed-beams exhibited higher stiffness under 3 PB loading owing to the periodicity and structural continuity of the composing cells, which effectively distributed the applied load. However, 3 PB structural beams composed of randomly-distributed architectural features exhibited crack jumps during failure, which played a crucial role in delaying premature failure. These crack jumps resulted from the irregular and stochastic nature of the internal architecture, which disrupted crack propagation paths and led to multiple crack arrests before complete structural failure. As a result, stochastic-based and GRF-based latticed-beams demonstrated superior toughness compared to their periodic counterparts. These findings provide insights into designing damage-tolerant latticed-beams and offer new strategies for enhancing their flexural performance.