猪后腿肌肉的动态拉伸性能

利用生物材料试验机和套管式高聚物霍普金森拉杆装置,试验得到了猪后腿肌肉在宽应变率范围 (0.02~2100s-1)内沿纤维方向和垂直纤维方向的拉伸应力应变曲线。编写程序对动态试验中高聚物杆波 的弥散和衰减效应进行了修正。对试验结果采用了1维方差统计分析,结果发现:应变率从0.02s-1上升到 2100s-1,肌肉在2个加载方向上流动应力都显著提高,即具有明显的应变率效应;低应变率下,纤维方向的 极限强度比垂直纤维方向的大,而破坏应变无显著不同,准静态应力应变曲线的形状与其他软组织类似,开始 为足趾区,后进入线性区,接着又有1段非线性区,最后达到极限强度,试样逐渐破坏;高应变率下,应力应 变曲线无足趾区,这是因为组织中的螺旋结构来不及伸直所致。垂直纤维方向比纤维方向有更高的初始模 量,但随应变增加,两者流动应力无显著差别,且纤维方向流动应力有逐渐高于垂直纤维方向的趋势。

Dynamic tensile properties of porcine ham muscle

Thetensilestress-straincurvesofporcineham musclealongthelongitudinalandtransverse directionsofthemusclefibrewereobtainedoverawiderangeofstrainrates(0.02~2100s-1).The experimentswereperformedbyusingthebiomechanicaltestingsystemandthepolymericsplitHopkinsontensilebar( SHTB)inthetubes.Aprogram wascompiledtomodifytheeffectofdispersion andattenuationofwavesintheviscoelasticpolymericbarusedasthetransmissionbarinthedynamic experiments.Statisticalanalysesweredonebyusingone-wayANOVA (p0.05).Theresultsshow thattheflowstressoftheporcineham muscleatthehighstrainrateof2100s-1isbothapparently higherthanthatatthelowstrainrateof0.02s-1alongthetwoloadingdirections,illustratingthe strainratesensitivitiesoftheporcineham muscle.Atthelowstrainrates,theultimatestrengthsalongthelongitudinaldirectionarehigherthanthosealongthetransversedirection, whereasthereare nosignificantdifferencesbetweentheirfailurestrainvalues.Thequasi-staticstress-straincurvesbehaveastheothersofttissues, exhibitinganinitialnon-lineartoeregion,followedbyalinearregion andsubsequentlyanonlinearregionpriortothegradualfailure.Atthehighstrainrates,thetoeregionvanishesbecauseithasnoenoughtimetopermitthestraighteningofthehelicalstructure. The initialmodulusinthetransversedirectionismuchhigherthanthatinthelongitudinaldirection.However, whenthestrainincreases,theflowstressesinthetwodirectionshavenosignificantdifference andtheflowstressinthelongitudinaldirectiongraduallyinclinestohigherthanthatinthetransverse direction.