Abstract
The paper presents the results of the study aimed at determining the elastoplastic properties of an Al/Cu bimetallic sheet consisting of aluminum and copper layers, which were joined by cold rolling. The values of elasticity coefficients in three orthotropic planes as well as the Kirchhoff modulus, and coefficient of internal friction in the perpendicular direction to the lamination were determined. The subjects of the analysis were also the values of limit stresses, uniform energy of elastic and plastic strain per unit volume, and coefficients of the hardening curve and normal anisotropy. The tests were carried out on bimetallic specimens with varying thicknesses of the copper layer, cut from the Al/Cu sheet in the direction of rolling and in the direction perpendicular to it. Two methods of determining the directional values of mechanical parameters were used in the tests, i.e., the uniaxial quasi-static tensile test and the dynamic acoustic resonance method. It was concluded that these methods made it possible to determine directional elastoplastic properties of the Al/Cu bimetallic sheet taking into account the variable share of components in the bimetal and the direction of cutting out specimens from cold-rolled sheet.
Highlights
The design of mechanical structures and processes of plastic forming require the knowledge of elastoplastic properties of deformable material
Three types of specimens were used in experimental tests, i.e., (a) Flat specimens with a ‘‘dog-bone’’ shape, made from Al/Cu bimetal (Fig. 1a), (b) Bimetallic Al/Cu specimens in the shape of rectangular prisms (Fig. 1b), (c) Aluminum specimens with the shapes and dimensions described in (a) and (b), obtained from bimetallic sheet, but completely devoid of the copper layer
Engineering curves e–r obtained from tensile tests served for determination of basic mechanical properties of the tested bimetallic structures
Summary
The design of mechanical structures and processes of plastic forming require the knowledge of elastoplastic properties of deformable material. The tests carried out on modern constructional materials, which are characterized by the heterogeneity of the internal structure and the directional changeability of the physical properties, are problematic. Additional difficulties during the tests are their form and shape, which are usually the results of the previously performed plastic forming. An example of such a structure may be a laminated sheet metal manufactured by joining two or more metal sheets characterized by different physical properties. There are three basic methods for production of bimetallic sheets. The most common and cost-effective methods of joining metal sheets from different metals are cold or hot rolling and the explosive method (Ref 3-6)
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