简介:Thispaperpresentsananalyticalstudyontheinfluenceofedgerestrainingstiffnessonthetransversevibrationsofrectangularplatestructure.AnimprovedFourierseriesmethodwasemployedtoanalyzethetransversevibrationofplatestructurewithgeneralelasticallyrestrainedboundaryconditions.AlinearcombinationofadoubleFourierseriesandeightauxiliarytermswassoughtastheadmissiblefunctionoftheflexuraldisplacementoftheplate,eachtermbeingacombinationofapolynomialfunctionandasinglecosineseriesexpansion.Theauxiliarytermswereintroducedtoensureandimprovethesmoothnessoftheoriginaldisplacementfunctionanditsderivativesattheboundaries.Severalnumericalexamplesweregiventodemonstratethevalidityandaccuracyofthecurrentsolution.Theinfluencesoftranslationalandrotationalstiffnessonthenaturalfrequenciesandmodeshapesofplatewereanalyzedbynumericalresults.Theresultsshowthatthetranslationalstiffnesshasbiggerinfluenceonthenaturalfrequenciesthantherotationalstiffness.Itisgenerallywellknownthatlittlechangeoftherotationalstiffnesshaslittleinfluenceonthemodeshapesofplate.However,thecurrentworkshowsthataverylittlechangeofrotationalstiffnessvaluemayleadtoalargechangeofthemodeshapesofasquareplatestructure.
简介:3月13日,经济合作与发展组织(OECD)公布了对主要经济体增长的最新预测。OECD预计,2018年全球经济将增长3.9%,2019年料增长3.9%。主要经济体方面,OECD预计,2018年中国经济将增长6.7%,2019年料增长6.4%;2018年欧元区经济将增长2.3%,2019年料增长2.1%;预计2018年美国经济将增长2.9%,2019年料增长2.8%;预计2018年日本经济将增长1.5%,2019年料增长1.1%。值得关注的是,OECD表示,美国税改将帮助2018和2019年美国经济增速提高0.5-0.75百分点。另外,OECD预计美国今年将加息4次,此前预期为3次。鉴于脱欧不确定性,OECD分析指出,英国今年的经济增速将在G20国家中排名靠后。此外,OECD经济学家PEREIRA表示,贸易战将威胁到全球经济反弹,可能将带来相当大的伤害。