简介：我们试验性地学习微观结构和自然奶牛皮革的机械行为。张力的测试用皮革脱衣被执行观察他们的变丑，爬并且失败。奶牛皮革的微观结构是从一些的不同尺寸的纤维的一个分层的、复杂网络到在直径的一些几百纳米，这被发现。他们显示出非线性的压力紧张关系和粘弹性的行为。湿度的效果也被检验。一根multilayered横梁的一个简单理论模型被建议描述最在紧张的基本行为。

简介：Theboundaryintegralequation(BIE)ofdisplacementderivativesisputatadisadvantageforthedifficultyinvolvedintheevaluationofthehypersingularintegrals.Inthispaper,theoperatorsδijandεijareusedtoactonthederivativeBIE.Theboundarydisplacements,tractionsanddisplacementderivativesaretransformedintoasetofnewboundarytensorsasboundaryvariables.AnewBIEformulationtermednaturalboundaryintegralequation(NBIE)isobtained.TheNBIEisappliedtosolvingtwo-dimensionalelasticityproblems.IntheNBIEonlythestronglysingularintegralsarecontained.TheCauchyprincipalvalueintegralsoccurringintheNBIEareevaluated.AcombinationoftheNBIEanddisplacementBIEcanbeusedtodirectlycalculatetheboundarystresses.ThenumericalresultsofseveralexamplesdemonstratetheaccuracyoftheNBIE.