【国外标准】 Standard Test Method for In-Plane Shear Properties of Sandwich Panels Using a Picture Frame Fixture

5.1 In-plane shear loading tests on flat sandwich constructions may be conducted to determine the sandwich panel in-plane shear stiffness, the face sheets’ in-plane strength, the core shear instability strength, or panel buckling response.5.2 This test method can be used to produce face sheet strength data for structural design allowables, material specifications, and research and development applications; it may also be used as a quality control test for bonded sandwich panels.5.3 Factors that influence the panel strength and shall therefore be reported include the following: face sheet material, core material, adhesive material, methods of material fabrication, face sheet stacking sequence and overall thickness, core geometry (cell size), core shear and compressive strength, core shear and compressive stiffness, adhesive thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, face sheet void content, adhesive void content, and face sheet volume percent reinforcement. Further, face sheet strength may be different between precured/bonded and co-cured face sheets of the same material.1.1 This test method covers determination of apparent in-plane shear strength and stiffness properties of flat sandwich constructions with composite face sheets. Permissible core material forms include those with continuous bonding surfaces (such as balsa wood and foams) as well as those with discontinuous bonding surfaces (such as honeycomb).1.2 The square test specimen with corner notches is mechanically fastened to a pinned metal frame along each edge. The frame is loaded in uni-axial tension which produces tensile forces in the frame elements at a 45° angle to the applied tension. These tensile forces act along the edges of the specimen to cause a state of predominately shear stress to transfer the applied force through the specimen. Procedure A uses a specimen without edge doublers; Procedure B uses a specimen with four discrete edge doublers; Procedure C uses a specimen with a continuous edge doubler.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3.1 Within the text the inch-pound units are shown in brackets.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. .