The mechanical durability of paper is a key consideration for applications ranging from shipping boxes to disposable medical substrates. Paper commonly experiences fatigue loading in such applications, but a high-cycle fatigue mechanism has not been identified. This research details paper’s high-cycle fatigue degradation mechanism. Paper specimens were loaded with monotonically increasing, constant, and sinusoidally varying cyclic stresses, and the resulting tensile, creep, and fatigue damage accumulation rates were compared. The difficulty in defining the size and growth of cracks in paper’s cellulosic fiber network were overcome with optically measured strain fields. We found that fatigue damage can accumulate via a fiber fracture mechanism, while ratchetting, creep, and tensile overload damage accumulation occurs due to failure of inter-fiber bonds. We also discovered the synergistic interaction between creep and high-cycle fatigue damage accumulation mechanisms, which is critical for extending the high-cycle fatigue life of paper.

纸的机械耐久性是从运输箱到一次性医疗基材的各种应用中的关键考虑因素。在此类应用中，纸张通常会承受疲劳负荷，但尚未确定高循环疲劳机理。该研究详细介绍了纸张的高周疲劳降解机理。纸标本加载有单调增加，恒定和正弦变化的循环应力，并比较了由此产生的拉伸，蠕变和疲劳损伤累积率。用光学测量的应变场克服了在纸的纤维素纤维网络中确定裂纹尺寸和裂纹扩展的困难。我们发现，疲劳破坏可以通过纤维断裂机制积累，而棘手，蠕变，由于纤维间粘合的破坏，会产生拉伸过载破坏积累。我们还发现蠕变和高周疲劳破坏累积机制之间的协同作用，这对于延长纸张的高周疲劳寿命至关重要。