| CAD/CAE techno lo gies, re lying o n the ir powerful functio na lities in des ign a ndana lys is of product, enab ling to dramatica lly improve the qua lity o f product, shorte nthe deve lop ment cyc le a nd lower the develop me nt cost, have become strong tools forcurrent product design and deve lop me nt.Howe ver, the representatio ns of mode l intraditio na l CAD syste ms, in whic h parametric continuous model is used, and that inCAE syste ms, in which a discrete mode l is invo lved, are d iffere nt. Prob le msintroduced by data model’s transfer and transition between the two systems havearoused people’s concern. How to perform an automatic conversion of the datamode l between the two syste ms, or provide a unified model representatio n for thetwo syste ms, na me ly CAD/CAE inte gration, has beco me a hot researching iss ue inthe CAD/CAE fie ld. This dissertatio n coup ling s ubdiv is io n surface modeling andboundary e le me nt method, success fully realizes boundary e le me nt method based onsubdivis io n s urface mode ling, natura lly integrating CAD and CAE. And the n severa lnumerica l comp utations re lated to the3D potentia l and linear elast ic proble ms areperformed with the method. In order to provide a better way to eva luate thecomputation res ults, a sc ientific co mputatio n vis ua lizatio n solutio n based onExod usII and ParaView is proposed. A comp lete p latform conta ining CAD mode ling(subd ivis io n s urface), CAE ana lys is (boundary e le me nt method nume rica lcomputation) a nd vis ua lizatio n postprocessor (ParaView scie ntific vis ua lizatio nsolutio n) is constructed. Additio na lly, in practica l e ngineering, the vis ua lizatio nproject is applied to s imulate concrete da m pouring process and provide avis ua lizatio n post-process ing so lution for its heat conductio n nume rica l ana lys is.BEM based on s ubdivis io n s urface mode ling has the fo llo wing c haracteristics:(1) In the BEM based on s ubdivis io n s urface modeling, subd ivis io n mes h is notonly used to represent geo metry, but a lso performed as the d iscrete model in theboundary e le me nt a na lys is. Subd ivis ion mes h provides a co mmon mode l and unifiedrepresenta tion for CAD design and CAE ana lys is, avo id ing the trans i tion o f datamode l between the two differe nt syste ms.(2) Subdivis io n mesh, d irectly used asboundary e le me nt mes h in BEM, provides an a uto matic a nd adaptive mes hgeneratio n sche me for boundary e le me nt ana lys is. Artific ia l errors, introd uced in thetraditio na l BEM d iscretization, can be minimized. In addition, the accurac y of geo metric representation and numerica l ana lys is can be contro lled by subdivis io nle ve l, according to d iffere nt des ign and a na lys is require me nts.(3) BEM based onsubdivis io n s urface mode ling inherits the ad vanta ges of both the subd ivis ion s urfacemethod and the BEM. It can represent structures o f arb itrary topolo gy withouttrimming and patc hing. Moreo ver, it req uires o nly d iscretization of the bo undary,reduc ing the dime ns io na lity o f a prob le m by one, and has high acc uracy.In the subd ivis io n surface mode ling, this d issertatio n presents two subd ivis ionmode ling sche mes, conta ining uniform s ubdivis io n s urface modeling a nd adaptivesurface mode ling. As each mesh facet is invo lved in each s ubd ivis ion le ve l,subdivis io n mesh of uniform s ubdivis io n surface mode ling grows uniformly andexpone ntia lly. And its overa ll q ua lity improves rap id ly. Howeve r, this sc he me isprone to lead to ins uffic ient subd ivis io n and e xcess ive s ubd ivis ion. S ince only mes hfacets, whic h meet the adaptive criteria, partic ipate the current subd ivis io n process,adaptive s ubd ivis ion enab les to red uce subd ivis io n in loca l flat re gio ns and increasesubdivis io n in loca l comp le x areas. Hence, adaptive subd ivis io n sche me canrepresent geo metry mode ls with less s ubd ivis ion meshes, a nd avo id the excess ivegrowth of the mes h quantity.In the numerica l ana lys is, BEM based on subdivis io n surface modeling isapp lied to solve3D potentia l and linear static e lastic prob le ms. Its convergence andaccuracy are investigated. Moreover, d ifferent c haracteristics of uniform subd ivis io nsurface and adaptive s ubdivis io n s urface in mode ling a nd ana lys is are s tud ied.Results demo nstrated that, as the s ubdivis io n le ve l increases, subd ivis io n mes hgrows, and its o vera ll qua lity improves; the accuracy o f the BEA for the subd ivis io nsurface mode ls become better and better. The converge nce rate and accurac y ofnumerica l a na lys is for the uniform s ubd ivis io n are higher. Howe ver, both theuniform subd ivis io n sche me a nd adaptive s ubd ivis ion sc he me can achie ve goodgeo metric models a nd high accuracy.In the post-processing, a scie ntific comp utatio n vis ua lizatio n so lution, whic h isbased on Exod usII and ParaView, for BEA is presented. Using ExodusII, a binarydata file whic h conta ins mode l informatio n and ana lys is results is writte n. Static dataat a comp utatio n time step or d yna mic data for severa l time steps is inc luded in thatfile. With vario us vis ua lization functio na lities pro vided by ParaView, users ca nqua litative ly and q uantitative ly ana lyze the ir data. Simulta neous ly, according toactua l needs and accusto med operatio ns, severa l ParaVie w secondary deve lop me ntsinc lud ing interface s imp lificatio n, color le ge nd updating a long with time steps, enlarging operation optimizatio n, annotatio n texts auto matic addition and so on,have been co mp leted. In order to obtain effic ient processing performa nce andstability in dealing with large-sca le data as we ll as to meet hardware upgraderequire ments, a64-bit vers io n ParaVie w applicatio n is comp lied.Fina lly, based on the concept o f multi-block dataset, a spec ia l visua liza tionpost-processing sche me is prese nted for multi-do ma in data mode ls, and then app liedto a practica l e ngineering prob le m o f co ncrete da m heat cond uction ana lys is. Withdata files conta ining specia l mark ing written by Exod usII and secondarydevelop me nts o f ParaView, the pouring process of concrete da m is s imulated.Simulta neous ly, for the specia l data set, in whic h comp lete mode l informatio n andwho le a na lys is results are conta ined, an e ffic ie nt a nimatio n sc he me is provided. Inthe animatio n sche me, only concrete da m la yers conta ining ana lys is res ults areshown in the current time step, in order to factua lly re flect the temperaturedistrib utio n of concrete dam in its the pouring and cooling process. Add itiona lly, thissche me is suited to the vis ua lizatio n post-processing for other ana lo gous multip ledoma in mode ls with time steps. |
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