RSA simulation of densification process  with randomly packed Cu–Ti powder particles  under pulsating load

Abstract

This paper uses a compactness algorithm to build a three-dimensional mesoscopic model by packing Cu–Ti particles with random size and location distribution. Cu–Ti powder particles' densification behavior and rheology under uniaxial compression and variable pulsating loads are studied. The initial position of each particle is compressed in its neighborhood following the proposed algorithm, and the size of the heterogeneous particles presents a lognormal distribution. By comparing the densification and average degree under different types of pulsating loads and the subsequent influence of frequency and amplitude on density, an optimized load spectrum based on an offline empirical parameter tuning strategy is proposed to improve the quality of the product. The results show that the algorithm proposed in this paper implies high compactness efficiency, and the mesoscopic model of powder is more accurate. During the densification, the powder particles in the cavity demonstrate a significant motion in the principal axis and spiral motion in the bottom corner. The bidirectional sine wave has the maximum density among the pulsating loads under the same amplitude and frequency. Pulsating loads with non-differentiating points may cause the particle displacement curve to produce a sharp peak at its crest. In contrast, the particle displacement curve is gentler under sinusoidal pulsating loads. Under bidirectional sine load, the low frequency and increasing amplitude of the load spectrum help to improve the density and average degree. The coefficient of friction of powder particles continuously changes during pressing. First, it increases, then decreases, and gradually becomes stable. The concave and cylindrical arcs formed by soft Cu particles at the contact point are smoother, and the shape of the particles is also more regular.