Significance and Use

The determination of the creep rate provides information on the behavior of sandwich constructions under constant applied force. Creep is defined as deflection under constant force over a period of time beyond the initial deformation as a result of the application of the force. Deflection data obtained from this test method can be plotted against time, and a creep rate determined. By using standard specimen constructions and constant loading, the test method may also be used to evaluate creep behavior of sandwich panel core-to-facing adhesives.

This test method provides a standard method of obtaining flexure creep of sandwich constructions for quality control, acceptance specification testing, and research and development.

Factors that influence the sandwich construction creep response and shall therefore be reported include the following: facing material, core material, adhesive material, methods of material fabrication, facing stacking sequence and overall thickness, core geometry (cell size), core density, core thickness, adhesive thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, specimen alignment, loading procedure, speed of testing, facing void content, adhesive void content, and facing volume percent reinforcement. Further, facing and core-to-facing strength and creep response may be different between precured/bonded and co-cured facesheets of the same material.

1. Scope

1.1 This test method covers the determination of the creep characteristics and creep rate of flat sandwich constructions loaded in flexure, at any desired temperature. 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. Within the text the inch-pound units are shown in brackets. 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 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.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C274 Terminology of Structural Sandwich Constructions

C393/C393M Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure

D883 Terminology Relating to Plastics

D3878 Terminology for Composite Materials

D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials

D7249/D7249M Test Method for Facing Properties of Sandwich Constructions by Long Beam Flexure

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

E1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases

E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases

Keywords

bending stress; core stress; creep; creep deflection; facing stress; sandwich; sandwich construction ; sandwich deflection; Creep; Creep deflection; Flexural testing--building materials; Sandwich core materials;

ICS Code

ICS Number Code 83.120 (Reinforced plastics)

DOI: 10.1520/C0480_C0480M-08

ASTM International is a member of CrossRef.

ASTM C480 / C480M