Shear punch testing

Characteristic features observed on load-displacement curves obtained using the shear punch apparatus. An initial and hardening stiffness in addition to the peak load are the primary metrics used to perform analytical comparisons. Like the conventional small punch test, the shear punch test also may be interpreted qualitatively. (Adapted from Kurtz et al. 2002.)... 

Kurtz S.M., C.W. Jewett, J.S. Bergstrom, et al. 2003. Miniature specimen shear punch test for UHMWPE used in total joint replacements. Biomaterials 23 1907-1919. 

How does the shear punch test differ from the small punch test Explain how the stress state in the deformed region evolves as the test progresses. 

Testing using the shear punch apparatus of convenhonal and highly cross-linked UHMWPE strongly suggested the representative behaviors in shear... 

Load-displacement curves observed by testing virgin and crosslinked UHMWPE in shear punch apparatus. Curves are quite similar, suggesting that changes in shear resistance are unlikely to explain the increased resistance to wear exhibited by crosslinked UHMWPEs. Materials tested were virgin GUR 1050 and GUR 1050 irradiated to 75 kGy and annealed at tempreratures below the melt point. (Adapted from Kurtz et al. 2002.)... 

The shear modulus of a material can be determined by a static torsion test or by a dynamic test employing a torsional pendulum or an oscillatory rheometer. The maximum short-term shear stress (strength) of a material can also be determined from a punch shear test. 

The measure of shear strength typically utilizes a punch-type shear fixture (Figure 14.19). The shear strength is equal to the load divided by the area. Thus, the sample is mounted in a punch-type shear fixture and punch-pushed down at a specified rate until shear occurs. This test is important for sheets and films but is not typically employed for extruded or molded products. 

Kc = compression coefficient of tested food Ks = shear coefficient of tested food A - area of punch P = perimeter of punch C = constant... 

ASTM D 732-90 Standard Test Method for Shear Strength of Plastics by Punch Tool, 3 pp (DOD Adopted) (FSC 9330) (MR) (Conun D-20)... 

This test covers the punch-type of shear test and is intended for use in determining the shear strength of test specimens of organic plastics in the form of sheets and molded disks in thicknesses from 0.127 to 12.7 nun (0.050 to 0.500 in.). 

Carter, J.M., Sorensen, S.E., Johnson, R.R., Teitelbaum, R.L. and Levine, M.S. (1983) Punch Shear Testing of Extracted Vital and Endodontically Treated Teeth. J. Biomechanics 16(10), 841-848. 

Utilized a miniature punch shear apparatus to determine shear strength and toughness perpendicular to the direction of dentinal tubules. Dentin harvested from the cemento-enamel junction to one-third the distance to the root apex. Strengths novel measurements, precise measurements, defined specimen location, defined orientation of testing. Limitations tooth type not defined for constrained tests, teeth stored in mineral oil prior to testing. 

ASTM D732-02 Standard Test Method for Shear Strength of Plastics by Punch Tool... 

The test specimen, disk or plaque, is placed in a clamp such that its upper and lower surfaces are securely supported. Specimen thickness should be between 0.127 and 12.7 mm (0.005 and 0.5 in.). A punch-type shear tool with a 25.4 mm (1 in.) diameter is bolted to the specimen through a hole drilled in the center and a load is applied to the... 

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