Stress relief - O-ryokukanwa

This is the phenomenon whereby when a certain strain is suddenly applied to an object and that strain is kept constant, the stress decreases monotonically over time. The stress at this time is called the relaxation stress, and the relaxation stress divided by the strain is called the relaxation modulus. Measuring stress relaxation is an important part of viscoelasticity experiments. In amorphous polymer solids and viscoelastic liquids, the relaxation stress becomes zero after a sufficient amount of time has passed, but in polymeric substances that are crosslinked or crystalline, the stress approaches a finite value and exhibits equilibrium elasticity. In a broad sense, stress relaxation also includes the decrease in stress over time when the strain is suddenly kept constant after a certain deformation history, such as the decrease in stress when the strain rate is suddenly made zero after a steady flow is induced. [See other terms] Creep, Maxwell model

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

物体にあるひずみを急に与えてそのひずみを一定に保っておくとき，応力がその時間経過とともに単調に減少していく現象．このときの応力を緩和応力といい，緩和応力をひずみで割ったものを緩和弾性率という．応力緩和の測定は，粘弾性の実験として重要なものである．無定形高分子固体や粘弾性液体では，時間が十分経つと緩和応力は0となるが，橋かけや結晶のある高分子物質では，応力は有限の値に近づき，平衡弾性を示す．なお，広義には，定常的な流れを起こさせた後，ひずみ速度を急に0にしたときの応力の減少など，ある変形履歴後，急にひずみを一定に保ったときの応力の時間経過に伴う減少を含めて応力緩和という．[別用語参照]クリープ，マクスウェル模型

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