Accurate measurement of mechanical properties of soft materials by introducing transition layers into test samples

•A facile approach to realize more accurate measurement of strength, toughness and other important properties of soft materials is proposed.•The underlying mechanism of alleviating stress concentration of soft materials that are in direct contact with hard clamps is uncovered, thus preventing premature failure of the material.•By using experiments and the corresponding bonded model, the effect of various geometric and material parameters on the present approach is explored. Soft materials loaded by conventional clamps are susceptible to damage caused by local stress concentrations, which leads to inaccurate measurement of strength, toughness, and other important properties. Herein, we propose a facile approach to solve the problem by introducing transition layers to test samples. The effectiveness of the proposed method is demonstrated by experiments and numerical analyses. It is found that the introduction of transition layers can stably and accurately reveal the stress-stretch relationship of soft materials by using the conventional hard clamps. What is more, the transition layers have almost no effect on the fracture toughness measurement for pure soft material samples and those with transition layers. These results should be of great significance for the measurement of various materials, and can serve as a design guidance of various soft material structures in blooming applications.