Subcritical statistics in rupture of fibrous materials: experiments and model.

摘要: Understanding fracture in solid materials is paramount for a safe engineering design of structures, and many efforts are still needed to obtain better physical picture. A puzzling observation the slow rupture material when loaded with constant external stress below critical threshold. Then, delay time before (or lifetime material) strongly depends on applied stress. Thermodynamics has slowly emerged as possible framework describe since early experiments have shown temperature dependence an Arrhenius law [1,2]. Statistical physics models assuming perfect elasticity recently proposed several predictions [3–8] well average dynamics growing crack [9]. Efforts also made from rheological properties such viscoelasticity plasticity [10,11]. To be able distinguish between various theoretical descriptions, more experimental work needed. We present this Letter experiment growth fibrous material. observed that grows by steps sizes whose distribution rather complex evolves function speed. This behavior can explained modeling elastic square lattice where pinned traps adapting model presented [9] thermally activated energy landscape multiple metastable states. The predicts statistical step very reasonable agreement typical functional form obtained subcritical point statistics. heterogeneity appears only characteristic mesoscopic length scale. effect disorder not been explicitly included simple model. system we consider twodimensional sheet macroscopic initial submitted load. geometry useful follow advance using direct observation, while would difficult three-dimensional because roughening instability front line usually occurs. used fax paper (width w � 21 cm, 24 thickness e 50 m) which natural scale fiber size. Scanning electron microscopy revealed size fibers 4 m ,w ith 20 m. In order reproducible results, was kept controlled low level humidity at least one day ’ 10%, during 5%. these conditions, Young modulus Y 3:5 GPa. mounted tensile machine both ends attached glue tape rolled times over rigid tubes. initiated center calibrated blade. force F sample measured gage perpendicular direction, corresponds opening mode I configuration. During experiment, feedback mechanism keeps precision 0:1 0: 5N response 10 ms. As consequence, amplitude