No abstract

A multi-layer high performance flex cable was used as a test vehicle for studying the effect of copper foil properties on low cycle fatigue properties of fine lme conductors. We fabricated the cable using copper foils for the three conductor layers, and used advanced organic composite dielectric materials for the internal dielectric layers. We fabricated the conductors using subtractive etching as opposed to using an additive plating process. The cable had to survive multiple cycles of fatigue bending around a sharp radius and we found that selection of copper foil was critical in determining fatigue life. We identified three distinct failure mechanisms in the cables that depended strongly on the surface roughness of the foil. We then studied the mechanical properties of he-standing copper foils of varying roughness and thickness to explain the behavior of the cables. We found that the surface roughness of the foils, and the ratio of roughness to thickness, strongly effected their fatigue performance.

Shot peening is one of the most widely used surface strengthening processes. The shot peening process involves multiple process parameters, which have a complex and interdependent impact on the peening effects, including compressive residual stress distribution and surface roughness. Accurately predicting the influence of shot peening parameters on the shot peening effect is a tough challenge in the simulation. In this paper, a shot peening simulation model is developed to investigate the influence of peening process parameters. The model encompasses material, target surface, and shot stream modeling. A method is proposed to reconstruct target surface model based on real rough surface data obtained via confocal laser scanning microscope. Unlike similar surface models, such as the Gaussian model, the reconstructed surface model replicates the peaks and valleys of the target surface along with their exact locations. A random multiple-shot model incorporating the reconstructed surface with predefined target coverage is developed via Python in Abaqus. Experimental verification on TC4 titanium alloy targets validates the simulation accuracy. The effects of peening parameters (shot velocity, density, diameter, and initial surface roughness) on residual stress distribution and surface roughness are investigated via the established model. Results reveal the significant influence of shot velocity and the relatively minor impact of other parameters. Increasing the diameter, velocity, and density of the shots result in higher residual stress levels and surface roughness. Notably, excessive initial surface roughness leads to abnormal increases in surface compressive residual stress.