There are provided an evaluation method and a prediction method for a and a technology to be reflected in a press die designing method. A deformation limit evaluation method includes evaluating the deformation limit on a sheared surface of a metal sheet in press-forming the sheared metal sheet. The deformation limit is evaluated and a crack in the sheared surface is predicted based on the relationship between an index value determined from two surface strain distribution gradients of a surface strain distribution gradient in a sheet thickness direction in the sheared surface and a surface strain distribution gradient in a bending ridge line direction by bending in a direction away from the sheared surface at an evaluation position among distributions of strains generated near the boundary between a bending outside surface and the sheared surface of the metal sheet to be bent and a tension generated in the sheared surface.

There are provided an evaluation method and a prediction method for a and a technology to be reflected in a press die designing method. A deformation limit evaluation method includes evaluating the deformation limit on a sheared surface of a metal sheet in press-forming the sheared metal sheet. The deformation limit is evaluated and a crack in the sheared surface is predicted based on the relationship between an index value determined from two surface strain distribution gradients of a surface strain distribution gradient in a sheet thickness direction in the sheared surface and a surface strain distribution gradient in a bending ridge line direction by bending in a direction away from the sheared surface at an evaluation position among distributions of strains generated near the boundary between a bending outside surface and the sheared surface of the metal sheet to be bent and a tension generated in the sheared surface.

To prevent a crack from occurring on a sheared end face due to press forming, a technology is provided for evaluating and predicting a crack limit of the sheared end face of a metal sheet and determining press forming conditions. In a deformation limit evaluation method for, when deforming by press forming a metal sheet subjected to shearing, evaluating a deformation limit of the sheared end face of the metal sheet, the deformation limit is evaluated by an index value obtained from two stress gradients at an evaluation position among stress distributions occurring in the vicinity of the sheared end face of the metal sheet due to the press forming, which gradients are a stress gradient in a sheet thickness direction and a stress gradient in a direction away from the sheared end face.

To prevent a crack from occurring on a sheared end face due to press forming, a technology is provided for evaluating and predicting a crack limit of the sheared end face of a metal sheet and determining press forming conditions. In a deformation limit evaluation method for, when deforming by press forming a metal sheet subjected to shearing, evaluating a deformation limit of the sheared end face of the metal sheet, the deformation limit is evaluated by an index value obtained from two stress gradients at an evaluation position among stress distributions occurring in the vicinity of the sheared end face of the metal sheet due to the press forming, which gradients are a stress gradient in a sheet thickness direction and a stress gradient in a direction away from the sheared end face.

Apparatus and methods of evaluating brittleness by measuring force applied to an electrode specimen by simulating a wound state of a jelly-roll type electrode assembly are disclosed herein. In an embodiment, a brittleness evaluation apparatus includes a jig unit, a driving unit, and a measurement analyzing unit. The jig unit includes two jigs, a groove formed between the jigs, a pressing plate, and guides. The jigs facing each other and have top surfaces formed in a horizontal plane and configured to receive a specimen arranged on the top surfaces along a length direction extending between and along the top surfaces. The pressing plate is arranged perpendicular to the length direction and configured to cause the specimen to bend by descending into the groove. The guides are located on each of the top surfaces of the jigs and configured to prevent distortion of the specimen during descent of the pressing plate.

Apparatus and methods of evaluating brittleness by measuring force applied to an electrode specimen by simulating a wound state of a jelly-roll type electrode assembly are disclosed herein. In an embodiment, a brittleness evaluation apparatus includes a jig unit, a driving unit, and a measurement analyzing unit. The jig unit includes two jigs, a groove formed between the jigs, a pressing plate, and guides. The jigs facing each other and have top surfaces formed in a horizontal plane and configured to receive a specimen arranged on the top surfaces along a length direction extending between and along the top surfaces. The pressing plate is arranged perpendicular to the length direction and configured to cause the specimen to bend by descending into the groove. The guides are located on each of the top surfaces of the jigs and configured to prevent distortion of the specimen during descent of the pressing plate.

A system for universal testing of metal sheet formability is described. The system discloses a cylinder barrel including two pistons for testing formability of the metal sheets. The driving force is provided by the hydraulic pressure of an incompressible fluid. The present application also describes an apparatus to perform various formability tests on metal sheets such as the bulge test, Nakazima test, Marciniak test, cupping test, and the blanking test. The system can also be used in hydroforming metal sheets.

A system for universal testing of metal sheet formability is described. The system discloses a cylinder barrel including two pistons for testing formability of the metal sheets. The driving force is provided by the hydraulic pressure of an incompressible fluid. The present application also describes an apparatus to perform various formability tests on metal sheets such as the bulge test, Nakazima test, Marciniak test, cupping test, and the blanking test. The system can also be used in hydroforming metal sheets.

In one version there is provided a test system including a layup tool having a layup surface, and two fairing bars attached to the layup surface. The test system includes the composite laminate having a plurality of stacked plies, and positioned between the two fairing bars. The test system includes fiber distortion initiator(s) positioned at one or more locations under, and adjacent to, one or more plies of the plurality of stacked plies. The test system includes two caul plates with a gap in between, and positioned over the composite laminate. When the test system undergoes a pressurized cure process with a vacuum compaction, a restricted outward expansion of the plurality of stacked plies by the fairing bars, and a pressure differential region formed by the one or more fiber distortion initiators at the one or more locations, create the controlled and repeatable out-of-plane fiber distortion in the composite laminate.

A method for improving a hemispherical dome test includes calculating a forming limit diagram (FLD) based on a plurality of simulated data associated with a sheet metal transformation technique. The method also includes performing zero friction analysis on the sheet metal transformation technique. The method also includes shifting the FLD based on the zero friction analysis.