hypermesh单元质量参数说明.docx
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hypermesh单元质量参数说明
hypermesh单元质量参数说明
Length(min)
最小长度
—
最小长度,计算使用以下两种方式:
(1)单元最短变长,对于非四面体网格;
(2)从节点到对角边(或面)的最短距离。
Minimumelementlengthsarecalculatedusingoneoftwomethods:
•
Theshortestedgeoftheelement. Thismethodisusedfornon-tetrahedral3-Delements.
•
Theshortestdistancefromacornernodetoitsopposingedge(orface,inthecaseoftetraelements);referredtoas"heighttoclosestnode".
YoucanchoosewhichmethodtouseintheCheckElementSettingswindow. NotethatthissettingalsoaffectsthecalculationofAspectRatio.
MinimumLength/Size
最小单元长度
—
使用两种方法计算最小单元长度:
(1)最短边长;
(2)节点到对边的高度。
HyperMeshuses2methodstocalculatetheminimumelementsize:
theshortestedge(inwhichthelengthoftheshortestedgeofeachelementisused)andtheheighttoclosestnode(whichismoreaccurate,butmorecomplex).
HeighttoClosestNode(HCN)iscalculateddifferentlyfordifferentelementtypes.
Fortriangularelements:
Foreachcornernode(i)HyperMeshcalculatestheclosest(perpendicular)distancetotherayincludingtheoppositelegofthetriangle,h(i).HCN=min(hi)*2/sqrt(3.0).Thescalingfactor2/sqrt(3.0)ensuresthatforequilateraltriangles,theHCNisthelengthoftheminimumside.
Forquadrilateralelements:
Foreachcornernode,HMcalculatestheclosest(perpendicular)distancestotherayscontainingthelegsofthequadrilateralthatdonotincludethisnode.Thefigureabovedepictstheselengthsasredlines.HeighttoClosestNodeistakentobetheminimumofalleightlinesandthefouredgelengths(thus,theminimumof12possiblelengths).
skew
面扭曲
三角单元的扭曲度计算方式如下:
从每个节点到对边中点的矢量以及两相邻边中点矢量的最小夹角
Skewoftriangularelementsiscalculatedbyfindingtheminimumanglebetweenthevectorfromeachnodetotheopposingmid-side,andthevectorbetweenthetwoadjacentmid-sidesateachnodeoftheelement.
Theminimumanglefoundissubtractedfromninetydegreesandreportedastheelement’sskew.
Taper
锥度
—
四边形对角节点连线分割成两个三角形。
锥度等于1减去最小三角形面积除以四边形一半面积的比值。
Taperratioforthequadrilateralelementisdefinedbyfirstfindingtheareaofthetriangleformedateachcornergridpoint:
Theseareasarethencomparedtoonehalfoftheareaofthequadrilateral.
HyperMeshthenfindsthesmallestratioofeachofthesetriangularareasto½thequadelement’stotalarea(inthediagramabove,"a"issmallest). Theresultingvalueissubtractedfrom1,andtheresultreportedastheelementtaper.Thismeansthatasthetaperapproaches0,theshapeapproachesarectangle.
Trianglesareassignedavalueof0,inordertopreventHyperMeshfrommistakingthemforhighly-taperedquadrilateralsandreportingthemas"failed".
Warpage
翘曲度
小于5度
依次沿对角线将四边形分为两个三角形,寻找这两个三角形所在面构成夹角的最大夹角,该角即为WarpAngle。
Thisistheamountbywhichanelement(orinthecaseofsolidelements,anelementface)deviatesfrombeingplanar. Sincethreepointsdefineaplane,thischeckonlyappliestoquads. Thequadisdividedintotwotriasalongitsdiagonal,andtheanglebetweenthetrias’normalsismeasured.
Warpageofuptofivedegreesisgenerallyacceptable.
3D网格质量检查补充参数
MinimumLength/Size
最短边长
使用两种方法计算:
(1)最短变长
(2)节点到对面最短距离。
HyperMeshuses2methodstocalculatetheminimumelementsize:
theshortestedge(inwhichthelengthoftheshortestedgeofeachelementisused)andtheheighttoclosestnode(whichismoreaccurate,butmorecomplex).
Intheheighttoclosestnodemethod,HyperMeshcalculatestheclosest(perpendicular)distancestotheplanesformedbytheoppositefacesforeachcornernode.
Theresultingminimumlength/sizeistheminimumofallsuchmeasureddistances.
Tetracollapse
网格塌陷
理想值1;
网格塌陷时逼近0;
不小于0.5
四面体网格高度根据四个节点到对面的距离计算,除以面积平方根。
最小的值除以1.24。
网格塌陷,这个值逼近0。
理想的四面体该数值为1。
非四面体单元统一赋值为1,以免Hypermesh误以为质量差的四面体单元。
Theheightofthetetraelementismeasuredfromeachofthefournodestoitsoppositeface,andthendividedbythesquarerootoftheface’sarea.
Theminimumofthefourresultingvalues(onepernode)isthennormalizedbydividingitby1.24. Asthetetracollapses,thevalueapproaches0.0,whileaperfecttetrahasavalueof1.0. Non-tetrahedralelementsaregivenvaluesof1sothatHyperMeshwon’tmistakethemforbadtetraelements.
Vol.AspectRatio
体长宽比
—
取四面体网格最长边除以最短变长
HyperMeshevaluatesTetrahedralelementsbyfindingthelongestedgelengthanddividingitbytheshortestheight(measuredfromanodetoitsopposingface). Other3-Delements,suchashexelements,areevaluatedbasedontheratiooftheirlongestedgetotheirshortestedge.
VolumeSkew
体扭曲度
0最优
1最差
仅检查四面体单元。
其他单元都被赋值为零。
体扭曲度等于四面体单元体积除以理想四面体体积。
Thischeckappliesonlytotetrahedralelements;allothersareassignedvaluesofzero.VolumeSkewisdefinedas1-shapefactor,soaskewof0isperfectandaskewof1istheworstpossiblevalue.
Theshapefactorforatetrahedralelementisdeterminedbydividingtheelement’svolumebythevolumeofanideal(equilateral)tetrahedronofthesamecircumradius. Inthecaseoftetrahedralelements,thecircumradiusistheradiusofaspherepassingthroughthefourverticesofthetetrahedron.
VolAR
高度与底面积比值