As highlighted by ScienceDirect in their article, “Determination of Flow Stress for Sheet Metal Forming Using the Viscous Pressure Bulge,” understanding the flow stress of sheet metal is critical for ensuring the quality of formed products. In sheet metal forming, the mechanical properties, particularly the flow stress, play a crucial role in determining metal flow and the final product’s quality. Accurate determination of this flow stress is essential for effective process simulation using the finite element method (FEM).
Traditionally, the tensile test has been the go-to method for assessing the mechanical properties of sheet metals. This test provides data on ultimate tensile strength, yield strength, maximum elongation, and reduction in area at rupture. However, its limitation lies in its uniaxial deformation condition, which does not fully represent the biaxial stress conditions experienced during stamping operations.
To address this, the Viscous Pressure Bulge (VPB) test has emerged as a superior alternative. The VPB test allows for the measurement of flow stress under biaxial stress conditions, which is more representative of actual forming processes like stamping. The test involves using a viscous material as a pressure medium, which enables the sheet metal to be deformed under conditions that more closely mimic those in real-world applications.
Through FEM simulations and experimental studies, researchers have identified key geometric and material variables that influence the forming process, such as dome wall thinning, dome radius, dome height, strain hardening index, material strength coefficient, and anisotropy. These factors are critical in developing a robust method for determining flow stress under biaxial deformation conditions.
By leveraging the VPB test, manufacturers can achieve more accurate simulations, leading to better control over metal flow and improved product quality in sheet metal forming operations. This testing method is particularly beneficial for operations that involve complex shapes and large strains, which are common in industrial stamping processes.
Click here to learn more about Borke Mold Specialists’ capabilities.
Article with all rights reserved, courtesy of sciencedirect.com.
