农业工程学报2017，Vol.33Issue(4)：248-257,10.DOI:10.11975/j.issn.1002-6819.2017.04.034
深水网箱护栏力学性能分析及优化
Mechanical property analysis and optimization of deep-water net cage guardrail
摘要
Abstract
Guardrail is an indispensable component of the deep-water net cage floating system, and it plays an important role to maintain culture volume of net cage and to resist the impacts of wave and current with net cage floating system. But there are few researches on guardrail mechanical properties of deep-water net cage. In order to improve the safety of deep-water net cage structure, three-dimensional solid models of guardrail were established by software Unigraphics NX, these models were calculated by finite element method of the software ANSYS Workbench. Firstly, mechanics properties of hexagon-triangle and circle type guardrails were investigated; Secondly, the collected data in the experiment and numerical simulation were analyzed by using linear and nonlinear regression methods to understand the mechanical performance of guardrails, and finally the design of guardrail was optimized with consideration of experiment and simulation results. The results of statics test showed that for high density polyethylene (HDPE) guardrail, tensile yield strength was 23.8 MPa, Young's modulus was 1240 MPa, and flexural strength was 25.2 MPa. Results of finite element modal analysis indicate that natural frequency range of guardrail was 14.25-33.59 Hz; stress range was 6.370-21.658 MPa. Fatigue vibration experiment was conducted by using hydraulic servo fatigue testing machine. Vibration frequency was set as 5 Hz, and vibration amplitude was 80% maximum compressive intensity of stress value (19.6 MPa). Results of fatigue test showed that fatigue fracture time was 23.5 h. According to finite element statics analysis, the biggest, medium and smaller displacement, stress and strain of guardrail was occurred in attack angle of 0°, 45°, and 90°. The displacement, stress and strain of concentrated load was higher than those of distributed load. The guardrail failed when the concentrated load was 4 kN in attack angle of 0°, and displacement, stress and strain was 70.47 mm, 28.922 MPa, 0.026434, respectively. The maximum displacement area was in the center of guardrail-handrail; the maximum stress area was in the bottom of guardrail-column. When attack angle to guardrail is 0°, the column was simplified as cantilever beam model. When attack angle is 90°, handrail was simplified as the form of tension and compression bar model. Based on finite element linear analysis of circular and hexagonal handrails, handrails of circle and hexagon failed when distributed loads were 6 kN and 16 kN, respectively, and stiffness of circular handrail was greater than that of hexagon significantly. Based on finite element nonlinear analysis of circular and hexagonal handrails, HDPE material model was set up by bilinear isotropic hardening model for isotropic materials (BISO). Deviations between simulation value and experimental value of guardrail and handrail at elastic stage were 8.67% and 0.27%, respectively. Deviation between simulation data and experimental data of handrails at plastic stage was analyzed by using method of Kolmogorov–Smirnov (K-S) two - factor fitting goodness examination. And the examined result of hexagonal handrail was p=0.8613>0.05, namely, there is no significant difference between finite element simulation and mechanics experiment in linear and nonlinear process. The sectional rigidity of guardrail was improved by designing the cross-sectional shape of guardrail-pipe. Compared with hollow-circle section of guardrail, flexural property of hollow-oval section and hollow- square section was increased by 6.58%, 6.83% respectively, in same materials. This study provides theoretical basis for the structural and mechanical properties for guardrail system.关键词
有限元法/力学性能/高密度聚乙烯/深水网箱/护栏Key words
finite element method/mechanical properties/high density polyethylene/deep-water net cage/handrail分类
农业科技引用本文复制引用
刘海阳,王绍敏,黄小华,陶启友,胡昱,郭根喜,宋利明..深水网箱护栏力学性能分析及优化[J].农业工程学报,2017,33(4):248-257,10.基金项目
中央级公益性科研院所基本科研业务费专项资金(中国水产科学研究院南海水产研究所)资助项目(2016TS14,2015TS12) （中国水产科学研究院南海水产研究所）
海南省重大科技计划项目(ZDKJ2016011) （ZDKJ2016011）
国家自然科学基金资助项目(31402349) （31402349）
海洋经济创新发展区域示范专项项目(GD2013-D01-001) （GD2013-D01-001）
广东省科技计划项目(2013B020501001) （2013B020501001）
