超高分子量聚乙烯绳结拉伸性能及断裂模式分析OA

The weaver's knot,as a representative functional knot,plays a critical role in global fishing industries.In 2024,knotted nets—which are constructed by connecting ropes with weaver's knots—generated direct economic revenues exceeding USD 153.1 million.However,with the deterioration of marine ecosystems,concerns have emerged regarding the safety and reliability of knotted nets.Annual global economic losses due to weaver's knots failure exceed USD 1 million.When knotted nets experience impact loading,the weaver's knots sustain complex stresses and exhibits the weakest strength,frequently initiating rupture and triggering chain-reaction failures.Functioning as a vulnerable component,the weaver's knots determine the overall reliability of knotted nets.Ultra-high molecular weight polyethylene(UHMWPE)is a linear polyethylene with a molecular weight exceeding 1.5 million.It offers advantages such as high strength-to-weight ratio,flexibility,exceptional abrasion resistance,and corrosion resistance,thereby making it suitable for weaver's knots research.Existing studies primarily focus on UHMWPE material properties and twisted cord parameters.Nevertheless,in practical production,weaver's knots are predominantly manufactured using twisted cords or braided ropes.The influence mechanisms of braiding parameters on the mechanical properties of the knots remain inadequately explored. To systematically investigate the influence of the braiding strand number and the braiding pitch on the tensile properties of knotted UHMWPE ropes,a series of UHMWPE braided ropes were fabricated with these as variable parameters(strands of 8,12 and 16,and pitches of 16,22 mm and 27 mm).Following the preparation of weaver's knot specimens from fixed-length rope segments,the tensile breaking strength,elongation at break,and knot efficiency were characterized.Subsequently,the corresponding failure mechanisms were analyzed.The experimental results showed that increasing the braiding strand number intensified stress concentration within the knot,resulting in reductions of 16.2%in tensile breaking strength and 5.1%in knot efficiency,while the larger braiding angle led to a 76.3%increase in elongation at break.Increasing the braiding pitch improved fiber strength utilization,raising the tensile breaking strength by 51.4%,but reduced the elongation at break and knot efficiency by 50.8%and 4.5%,respectively.A braiding compactness index(BCI)was defined,and knots with different BCI values exhibited stress concentration failures caused by frictional shear and bending deformation within the knot.In addition,the weaker geometric constraints in low-BCI knots aggravated the asynchrony of fracture,leading to severe yarn slippage. Clarifying the impact patterns of the braiding strand number and braiding pitch on the mechanical behavior of knots provides a scientific foundation for parameter control in production,which,coupled with the introduction of a braiding compactness index that links geometry to performance,establishes a new methodology for quantifying knot reliability.