C273/C273M Standard Test Method for Shear Properties of Sandwich Core Materials has been revised to C273/C273M-18
Significance and Use
5.1 The core shear properties are fundamental properties that are used in the design of sandwich panels. This test method provides information on the force-deflection behavior of sandwich constructions or cores when loaded in shear parallel to the plane of the facings. From a complete force-deflection curve, it is possible to compute core shear stress at any force (such as the shear stress at proportional limit, at yield, or at maximum force) and to compute an effective core shear modulus.
5.2 The test does not produce pure shear, but the specimen length is prescribed so that secondary stresses have a minimum effect. Approximate shear properties can also be obtained from a sandwich flexure test (see Test Method C393).
5.3 This test method provides a standard method of obtaining sandwich core shear data for material specifications, sandwich panel design, research and development applications, and quality assurance.
5.4 Factors that influence core shear strength and shall therefore be reported include the following: facing material, core material, adhesive material, methods of material fabrication, core geometry (density, cell size, orientation, and so forth), adhesive thickness, specimen geometry and associated measurement accuracy, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, and adhesive void content. Further, core-to-facing strength may be different between precured/bonded and co-cured facings in sandwich panels with the same core and facing material.
1.1 This test method covers the determination of shear properties of sandwich construction core materials associated with shear distortion of planes parallel to the facings. It covers the determination of shear strength parallel to the plane of the sandwich, and the shear modulus associated with strains in a plane normal to the facings. The test may be conducted on core materials bonded directly to the loading plates or the sandwich facings bonded to the plates. 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 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.
1.2.1 Within the text the inch-pound units are shown in brackets.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
C271/C271M Test Method for Density of Sandwich Core Materials
C393 Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D2584 Test Method for Ignition Loss of Cured Reinforced Resins
D2734 Test Methods for Void Content of Reinforced Plastics
D3171 Test Methods for Constituent Content of Composite Materials
D3878 Terminology for Composite Materials
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials
D5687/D5687M Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
D5961/D5961M Test Method for Bearing Response of Polymer Matrix Composite Laminates
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics