engleski

Recording of a true stress-strain curve by the use of the modified hydraulic bulging

From classical hydraulic bulging of circular diaphragm, a new method has been derived, named ; modified hydraulic bulging on the sphere, with a purpose of recording the true stress – strain curves. New method allows more accurate determination of membrane stress in the deforming material. Assumption on the bulk geometry is no longer needed since modification, using sphere as an obstacle, determines the radius of curvature needed in acquisition of membrane stress. Performing modified hydraulic bulging upon just one test specimen, yields three points of stress-strain curve. Experimentally obtained points have different strains, covering different areas of strain ; small, medium and large deformations, within a single experiment. Use of the small transducer integrated in tooling, enables acquisition of force and thus reliable stress acquisition upon the known (spherical) geometry. Recorded true stress-strain curve has been used in creation of finite element model of the modified hydraulic bulging on the sphere.

Modified hydraulic bulging; stress - strain curve; hydroforming; FE simulation

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