Testing of foams

Foams are lightweight cellular materials that are widely used in applications such as packaging, thermal insulation, sound absorption, underwater vehicle structures, and as the core in sandwich structures used in aircraft. Testing of foams to obtain reliable properties that are relevant to a given application is a significant challenge. High damping, high compressive or tensile strain, and high volume of air in the structure are among the challenges that make it difficult to apply the common test methods to these materials. For example, use of strain gauges for tensile or compression testing is usually not possible because bonding the strain gauges to the surface of a cellular material may not be possible, the small measurement range of a strain gauge may not be enough to capture the strain in the entire loading range, and microscopic material structure may dominate the measurement. This chapter discusses test techniques that include quasi-static compression, high strain rate compression, impact, dynamic mechanical analysis, vibration methods, and imaging techniques that are relevant to testing of foams. The imaging methods include ultrasonic imaging and microCT-scanning. Test techniques are described and results on representative foam materials are presented to understand the test outcomes.