Investigating property-porosity relationships for micro-architected lattice structures

Area of Science:

• Materials Science
• Mechanical Engineering
• Additive Manufacturing

Background:

• Micro-architected materials offer tunable mechanical properties and lightweight designs.
• Understanding the relationship between relative density (RD) and mechanical properties is crucial for effective design.
• Existing models like the Gibson-Ashby power law may not accurately represent material behavior across a wide range of RDs.

Purpose of the Study:

• To investigate the mechanical response of Ti-6Al-4V gyroid structures over a broad range of relative densities (RD).
• To evaluate the applicability of the classical Gibson-Ashby power law scaling.
• To develop an improved analytical model for predicting mechanical properties as a function of RD.

Main Methods:

• Experimental testing of Ti-6Al-4V gyroid structures with varying RDs, unit cell sizes, and sheet thicknesses.
• High-fidelity finite element analysis (FEA) for detailed mechanical response simulation.
• Development and validation of analytical models.

Main Results:

• The Gibson-Ashby power law scaling inadequately describes the mechanical properties (modulus and yield stress) of gyroid structures across the studied RD range.
• Deviations from Gibson-Ashby scaling indicate a transition from structure-dominated to material-dominated mechanical behavior.
• An analytical model was proposed to more accurately capture the evolution of mechanical properties with RD.

Conclusions:

• Classical scaling laws require refinement for micro-architected materials, especially across wide RD variations.
• The transition from structure-dominated to material-dominated behavior is a key factor influencing mechanical properties.
• Accurate modeling of mechanical properties versus RD is essential for designing advanced architected materials.