Stress Relaxation Tester for Reinforcing and Prestressing Steel
Qualitest's QT-SR Series Stress Relaxation Tester is designed to measure the stress-relaxation behavior of metals such as pre-stressed concrete strands, pre-stressed concrete bars, steel ropes, and more. The test involves deforming a specimen by a specific amount and monitoring the decrease in stress over an extended period at a constant elevated temperature.
The ASTM E328 Standard Test Methods for Stress Relaxation Tests for Materials and Structures provides guidelines for these tests. Stress relaxation is a critical factor to consider when designing mechanical fasteners that require permanent tightness, as failure can occur over time if this property is neglected.
According to ASTM, typical applications tested using this standard include bolted or riveted assemblies, press or shrink-fit components, rolled-in tubes, gasket tightness, the constraining force of springs, and the stability of wire in pre-stressed concrete. This test is also applicable for measuring stress relaxation in areas with high stress concentrations. A controlled testing environment is essential to avoid alterations in the material's properties due to environmental factors.
