Wear behavior of additively manufactured auxetic re-entrant Ti6Al4V structures

Abstract

Wear behavior plays a critical role in determining the durability and functional performance of lattice structures subjected to cyclic or contact loading. Auxetic lattice architectures, characterized by a negative Poisson's ratio, offer superior mechanical response and energy absorption compared to conventional cellular designs. This study investigates the reciprocating wear behavior of additively manufactured Ti6Al4V auxetic structures, focusing on the influence of unit cell geometry. Prismatic samples (20 × 10 × 10 mm³) with varying strut thicknesses (t₁, t₂), inclined strut lengths (L), and inter-strut angles (θ) were fabricated using laser powder bed fusion. Reciprocating wear tests were performed under dry conditions using 100Cr6 steel balls as a counter body. The tribological response was evaluated based on the coefficient of friction (COF), specific wear rate, and worn surface morphology. Results revealed that the specific wear rate ranged from 2.023× 10⁻⁴ to 1.875 × 10⁻³ mm³/m·N, strongly influenced by both horizontal and inclined strut thicknesses as well as out-of-plane geometry. The COF varied between 0.31 and 0.45 and was primarily governed by the out-of-plane thickness and strut configuration. These findings highlight the critical role of unit cell geometry in controlling wear mechanisms and frictional response of additively manufactured auxetic lattices.