Development of a Highly Efficient Large Deformation Stress Relaxation Test Method for Rubber Using Two Different Material Tests

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04162
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: University of the Ryukyus
• Principal Investigator: Fujikawa Masaki 琉球大学, 工学部, 准教授 (70549047)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: ゴム / 応力緩和履歴 / 予測 / 動的粘弾性試験 / 分数階微分モデル

Outline of Final Research Achievements

A new method has been developed to predict the long term stress relaxation history from the results of dynamic mechanical analysis and short term stress relaxation tests (SRT). To confirm the validity of the method, it was applied to the SRT of several SBR materials with different carbon black contents. The results showed that the new method can accurately predict the stress relaxation history for more than half a day based on the results of SRT of about 1 to 2 minutes. Regarding the versatility of the method, the results were confirmed to be comparable for silica-filled SBR materials. Using these results, predicted values of the steady-state stress-strain relationship of rubber, which is generally difficult to measure, was presented.

Free Research Field

実験力学、計算力学

Academic Significance and Societal Importance of the Research Achievements

応力緩和試験（Relax-試験）は、長時間負荷後のゴムの材料軟化現象や、定常状態の応力－ひずみ関係を計測する目的で一般に使用される。本試験は、例えばシーリング材のような装着後に長時間使用し続ける機器や、ゴムの力学特性を計算するための材料モデリング（応力－ひずみの関係式）の選択や構築に必要不可欠の情報となる。
しかし効率的な長時間Relax-試験はこれまで開発されておらず、経験や種々の仮定に基づく代替え手段による方法などが一般的であった。本法は体系的な研究により、これらの効率化と高精度化を可能にするものであり、学術面への貢献のみならず、工業面での実用が期待される。