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Shear Loader and Performing Pure Mode II or Mixed Mode I and Mode II Shear Loading

Patent Number: 10,761,002

Abstract

A shear loader subjects a shear load on a sample and includes: a first shearer including: a first shearing face that provides a shearing plane; a first mating face; and a first knife edge; a second shearer including: a second shearing face; a second mating face; and a second knife edge, the first shearer and the second shearer having relative motion to provide the shear load to the sample; a first load cell; and a second load cell, the first load cell and the second load cell having relative motion in a load direction that is orthogonal to the shearing plane and orthogonal to the shear direction, such that relative motion of the first load cell and the second load cell along the load direction subjects the sample to a side load along the load direction; and a sample region that receives sample bounded by the mating faces and load faces.

Patent Description

The device is a shearing system that is essentially a portion of a large scissors, used to precisely shear a specimen while recording the loads and deformations. It consists of two metallic half­ devices that are installed in a standard servohydraulic mechanical testing system. The sample is placed between the shearing platens after decorating with a speckle pattern to be used by the digital image correlation (DIC) strain mapping system. The sample is sheared in half while the loads and deformations are recorded. From this data, the pure shear strength, strain to failure and shear modulus can be calculated.

It is applicable for testing the strength of adhesive joints, solid state welds, spot welds as well as the interlayer strengths and fracture toughness of polymer composites.

Features

The noteworthy features of this system are (1) it can be used with any standard test frame of sufficient capacity, (2) there are adjustors to locate the plane of shear within the thickness of the sample to test specific locations, (3) it has been used to test the shear strength of polymer carbon fiber composites, glued adhesive joints, and spot welds, and (4) the sample size required is only 1 cm square  by thicknesses but can  be as small as 0.2 mm.

Created January 30, 2021, Updated February 11, 2021