Measuring stress relaxation

• Rod Cross ^[1]
  1. [1] University of Sydney

     University of Sydney

     Australia

     
• Localización: The Physics Teacher, ISSN 0031-921X, Vol. 63, Nº. 1, 2025, págs. 72-72
• Idioma: inglés
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• Resumen

  • If a tennis racket is strung at a tension of about 30 kg (actually about 300 N), then the player and the tennis stringer would probably assume that the string tension will remain constant for at least a couple of sets of tennis. In fact, the tension will drop to about 25 kg after about 5 minutes. That’s because tennis strings are viscoelastic, meaning they are partly viscous and partly elastic.1 The decrease in string tension is called stress relaxation, and it happens to all plastic materials and to a smaller extent with metals when they are subject to compression or tension. The effect is usually studied using a materials testing machine. A cheap one costs about $20,000, so they are not commonly available in schools or even university physics departments.