Shen Ming-Yuan, Chiou Yung-Chuan, Tan Chung-Ming, Wu Chia-Chin, Chen Wei-Jen
Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 41170, Taiwan.
Department of Biomechatronic Engineering, National Chiayi University, Chiayi 60004, Taiwan.
Materials (Basel). 2020 Mar 5;13(5):1170. doi: 10.3390/ma13051170.
In this study, the effect of wall thickness (15-25 mm) on the stress-strain response of hollow-cylinder rubber fenders were investigated by conducting monotonic compression tests. It was found that a progressive increase in lateral bending deformation was observed during monotonic compression. Simultaneously, the extent of the lateral deflection decreased notably with an increasing wall thickness. From the experimental results, the fact is accepted that buckling occurred in the tested fender due to the fact that the ratio of the height to the wall thickness was higher than four in all of the considered cases. Moreover, an s-shape profile appeared in the stress-strain curves, which became clearer as the wall thickness was reduced from 25 to 15 mm. To assess the performance of fenders objectively, an energy-effectiveness index, C E R , was introduced to quantify the energy absorption capacity of the fender. From the experimental observations, it was inferred that the contact area of the folded inner surface of the fender produced under compression generated an additional reaction force and affected the shape of the stress-strain curve since the measured load consisted of two reaction forces: one caused by the self-contact area, and the other resulted from the compression-bending deformation that occurred in the side wall of the fender. To examine this assertion, a finite element analysis (FEA) was conducted and confirmed the effect of the reaction force on the sensitivity of the s-shape characteristic of the stress-strain curve. Finally, a polynomial regression was conducted and the calculated results based on the fourth-degree stress polynomial function correlated very well with the measured stress-strain curves.
在本研究中，通过进行单调压缩试验，研究了壁厚（15 - 25毫米）对空心圆柱橡胶护舷应力 - 应变响应的影响。研究发现，在单调压缩过程中，横向弯曲变形逐渐增加。同时，随着壁厚的增加，横向挠度的程度显著降低。从实验结果来看，在所考虑的所有情况下，由于高度与壁厚之比高于4，试验护舷中发生了屈曲这一事实是被认可的。此外，应力 - 应变曲线中出现了S形轮廓，随着壁厚从25毫米减小到15毫米，该轮廓变得更加明显。为了客观评估护舷的性能，引入了能量效率指数CER来量化护舷的能量吸收能力。从实验观察结果推断，压缩时护舷折叠内表面的接触面积产生了额外的反作用力，并影响了应力 - 应变曲线的形状，因为测量的载荷由两个反作用力组成：一个由自接触面积引起，另一个由护舷侧壁发生的压缩弯曲变形产生。为了检验这一论断，进行了有限元分析（FEA），并证实了反作用力对应力 - 应变曲线S形特征灵敏度的影响。最后，进行了多项式回归，基于四次应力多项式函数的计算结果与测量的应力 - 应变曲线相关性非常好。
