Abstract
The purpose of this paper is to simulate a complex forming process with parameters identified from tensile and shear tests. An elastic-plastic model is retained which combines a Hill’s 1948 anisotropic criterion and plastic potential using a non-associated flow rule. Firstly, a mechanical characterization is made with homogenous tests like tensile and shear tests [1]. On the other hand a process of micro Single Point Incremental forming is simulated [2]. It consists in deforming a clamped blank using a hemispherical punch which has a small diameter compared to the blank dimensions. From a small-size sheet of 0.2 mm thick, a square-based pyramid is obtained incrementally, with a define height path and advanced speed, by a tool instrumented to measure the forming force, which deforms locally the material. It is shown that the non-associated flow plasticity model leads to a good agreement between experimental and numerical results for the evolution of the punch force during the process.
Highlights
The miniaturization of device is a race which started three decades ago, and this tendency led to a high demand for components with sub-millimeter dimensions
In order to meet the needs of industries with increasing production rates, the forming processes by plastic deformation remains the most common technological solution for the manufacture of miniature parts, such as those found in the watchmaker industry
The identification of the constitutive law is often performed by using mechanical tests, i.e. tensile, bending, and shear tests [6]
Summary
The miniaturization of device is a race which started three decades ago, and this tendency led to a high demand for components with sub-millimeter dimensions. Hill has the advantage to use a quadratic function with anisotropic coefficients which describe the values of the Lankford ratios and the flow stress for different orientations relative to the rolling direction. The objective of this study is to simulate a micro Single Incremental forming process with parameters identified from tensile and shear tests. The Lankford ratios r0, r45 and r90 are accessible thanks to the tensile test They correspond to the slope of the transverse strain curve according to the normal strain ε22p = f(ε33p). It is observed that the mechanical properties in the transverse direction are higher both during the tensile and the shear tests, especially the yield stress is higher. Results show that the CuBe alloy has a normal anisotropy enough low but a pretty significant planar anisotropy
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