Parson BTEC Lvl _ Highr Nationals in Enginring (RQF) Unit 37: Virtual Enginring Unit Workbook 1 in a sris of 1 for this unit Larning Outcos 1, 2, 3 & 4 Virtual Enginring Pag 1 of 9
1.1 Enginring Dsign Fundantals Within any organisation, a dsign nginr has a ky rol to ay in dlivring a product or srvic to th nd custor. Thy hav th rsponsibility of rsarching and dvloping nw idas and/or odifying xisting products in ordr to ak iprovnts. Whn inting a nw dsign procss th dsign nginr ust listn to th rquirnts of th custor, whilst considring th liitations and rquirnts of anufacturrs, supirs, fittrs, softwar, tsting procdurs and nd usrs. Th purpos of a dsign nginring procss is to produc a product/srvic that is fit for purpos and fulfils th original rquirnts of th custor. 1.1.1 Standards & Rgulatory Coianc In ordr to nsur that all nginring products t crtain lvls of quality and ar saf to us and oprat, thr ar sts of standards that hav bn rfind ovr ti to provid nginring laws and practical constraints, rprsnting good practic across th ntir spctru of nginring. Thr ar currntly diffrnt sts of standards dpnding on th disciin of nginring and th country in which th ar bing apid. Gnrally, in Europ nginring copanis confor to EN (Europan Nors) standards. In th U.K. so copanis coy with EN standards and so with British Standards (BS), whilst othrs coy with a ix of both. In Arica thr ar a st of standards known as ANSI (Arican National Standards Institut), whilst ASTM (originally th Arican Socity for Tsting & Matrials) and ISO (Intrnational Organisation for Standardisation) ar both standards organisations which oprat globally. 1.1.2 Capabilitis & Liitations of Coputr-Basd Modls In ordr to coy with rgulations, copanis oftn us coputr-basd odls to tst thir dsigns bfor thy actually go into production. Iagin a boat anufacturr rquirs a bow post to b dsignd for a nw boat, and in ordr for thir product to pass rgulations this bow post ust b capabl of withstanding a crtain pull forc. Rathr than just dsigning a bow post, having it anufacturd and thn idiatly having it physically tstd, th copany can prfor virtual tsts on a coputr odl of th post to dtrin if th dsign is likly to pass or fail th physical tst. In doing a virtual tst, this givs th dsignr valuabl inforation about whthr or not thir dsign is fit for purpos. If th dsign fails this virtual tst thn th dsignr can ak changs to atrial, dsign or thod of fixing/anufactur and thn rtst th dsign until it passs. Altrnativly, if th part that has bn dsignd is ovr-nginring thn potntially so costs could b savd by roving xcss atrial, siifying th dsign or using a lss xpnsiv atrial. Of cours, a dsign nginr can us anual calculations to prdict th physical prforanc of a product thy ar dsigning; howvr, this can b vry labour intnsiv, ay tak a lot of ti and is suscptibl to huan rror. Using coputr-basd odls incrass spd, accuracy, rliability, adaptability and rducs th spac rquird for storing rcords. Although thr ar any advantags to coputr-basd odls, thr ar svral liitations; coputr systs hav zro IQ and ar thrfor only abl to prfor spcific tasks that thy ar prograd for, coputr systs ar also unabl to ak dcisions rquiring huan valuation skills, finally a coputr is unabl to us coon-sns or logic as a huan is abl to. Pag 5 of 9
1.2 Dsign, Analysis and Siulation Tools Dpnding on th industry or th contxt in which an nginr is oprating thy ay nd to us diffrnt coputr-basd dsign, analysis and siulation tools. 1.2.1 2D and 3D CAD Within a profssional copany, whn thr is a rquirnt for a nw product it is highly likly that it will b dsignd using Coputr Aidd Dsign (CAD), without this it will b difficult to counicat th dtails of th dsign to a supir. Whilst a dtaild drawing can b producd by hand, it is far quickr to us CAD and it also aks it asir to rctify istaks or ak changs to dsigns. Thr is a full xanation of capabilitis and liitations in th prvious sction. Thr is a thora of diffrnt CAD softwar packags that can b usd for profssional dsign, as such thr ar also any diffrnt fil forats but gnrally thy can usually b transfrrd fro on packag to anothr. 2D CAD is usd to produc tchnical drawings and is frquntly utilisd in th production of building layouts, floorans and lctrical schatics. 3D CAD is gnrally usd to produc thr-dinsional odls of parts and assblis that can b anipulatd in 3D spac and thn usd to produc 2D anufacturing drawings for anufactur. It is usd by nginrs, product dsignrs and architcts to produc a vast thora of diffrnt products and structurs. CAD has dvlopd assivly sinc it s concption in th arly 1980 s and is continuing to iprov by offring a bttr usr xprinc through or intuitiv oprations and as of accss. 1.2.2 Finit Elnt Mthod Th finit lnt thod, sotis rfrrd to as finit lnt analysis (FEA) is usd in ordr for nginrs to prdict th bhaviour of systs and parts, typically in th aras of hat transfr, lctroagntic potntial, fluid flow and structural analysis. Ths systs can b static or dynaic and on, two or thr dinsional. To prdict th bhaviour of a syst, th finit lnt thods looks at it in trs of a nubr of algbraic quations rathr than th syst as a whol. Th probl is dividd into a larg nubr of uch sir parts, known as finit lnts and brought togthr at th nd of th procss to giv an ovrall answr. With rgards to structural analysis, FEA is usd vry frquntly in functions such as calculating th failur point of parts and structurs whn put undr load. In ordr to ak a siulation of a structur, a sh is cratd which consists of a hug nubr of sall lnts, which whn addd togthr ak up th structur ovrall. Ths individual lnts produc known valus at ach cornr and ths points ar calld nodal points or nods. Whn ach individual lnt and nod has bn workd out, th sh can b convrgd, and an ovrall rsult obtaind. If a or prcis ovrall rsult is rquird thn th sh can b rfind, which is ssntially rducing th siz of ach individual lnt to rduc rrors in calculations. Pag 6 of 9
Figur 1.1: FEA Siulation of a Conncting Rod with Visibl Msh Th athatical for of FEA is a cox and ti-consuing procss, thrfor coputr-basd odls ar usd to prdict this bhaviour, th visualisation of th nd product is also vry ffctiv at quickly counicating issus in dsign to th dsignr(s). As with any prdiction, th rsults cannot b guarantd to b xactly 100% accurat. It is thrfor prudnt to chck th rsults of th siulation against historically siilar systs; xprincd nginrs usually hav an ida of th xpctd rsults and can thrfor idntify rronous siulation rsults. Si hand calculations can also b carrid out to confir siulatd rsults on or si systs such as singl ba dflction. Th sa siulation can also b carrid out by anothr nginr and/or using diffrnt softwar to confir th siulation rsults ar accurat. 1.2.3 Coputational Fluid Dynaics (CFD) CFD involvs analysing fluid flow using coputational thods and producing siulations of th flow of liquids or gass and how thy intract with boundaris and/or solid objcts. This tchniqu uss th sa thod as FEA of crating a sh in ordr to analys a sold part/assbly, howvr it apis fluid flow princis to dtrin th outco of th syst. Thr ar various diffrnt softwar packags that can b usd to siulat flow and chanical systs, profssional organisations oftn us on ovrall softwar providr for 3D dsign as wll as siulation so that th 3D odl can b asily igratd to th siulation ara. Thr ar also any pics of softwar that ar dvotd to siulation solly and 3D odls in various forats can b iportd into ths siulation progras to b analysd. CFD is usd xtnsivly in Hating, Vntilation and Air Conditioning (HVAC) apications such prdicting air flow of a nw as air conditioning systs within a building. It can also b usd for aiding th dsign of xhaust and diffusr systs, as wll as analysing air flow rlationships with vhicls, buildings an vn a bird in flight. Thr ar a hug nubr of uss for CFD and, as it is an incrdibly powrful tool to siulat hat transfr in fluids it can b usd to siulat ral lif situations highly accuratly. Pag 7 of 9
Figur 1.2: CFD Siulation of Airflow around a Forula On car Challng Th bst way to bco failiar with ths coputr-basd odls including CAD, FEA and CFD is to practic using th as frquntly as possibl. Rgistr with Siscal (https://www.siscal.co/) and cot th Solid Mchanics Siulation (FEA) and th Fluid Flow Siulation (CFD) tutorials (https://www.siscal.co/tutorials). Figur 1.2: Siscal Tutorials Pag 8 of 9
1.3 Intrprtation of Rsults & Dtrining Faults Onc a siulation has bn conductd, w ar prsntd with so rsults that rquir intrprting, rbr that just bcaus th siulation has prsntd a st of rsults it dos not ncssarily an ths rsults ar rliabl. Figur 1.3: Von Miss Strss Rsults In th xa of a solid chanics siulation, thr ar a larg nubr of diffrnt typs of loads to apy to a part and thr ar also any diffrnt rsults that th siulation softwar can b ad to disay. In gnral, in structural analysis, aras in rd indicat a highr valu of strss, whras blu aras indicat lowr strss aras. By just glancing at th rsults of th abov von Miss strss siulation, an nginr ay assu that th part is prforing wll as th strsss ar apparing in th aras on would xpct. Howvr, it is vry iportant to actually chck thos strss valus bcaus thr ay b so valus that xcd th yild strss of th atrial. A usful tip is to chang th sttings of th siulator so that valus of von Miss strsss abov th atrial yild strss ar highlightd in a diffrnt colour. This will thn show xactly whr th part is likly to yild, and an nginr can thn chang so proprtis of th part to itigat this yilding. In addition, whr a part has aras of zro radius (sharp cornrs) occasionally ths will lad th siulator to dlivr rronous rsults bcaus it attpts to solv for infinity at ths aras. In ordr to dfnd against ths kinds of rrors, it is always a good ida to rrun th siulation with a diffrnt sh siz and chck that th rsults ar siilar. Siy prsnting a colourful iag of strss or dflction is not a full xanation of th rsults, it rly shows whr th rlativly high strss rgions ar locatd, it can b usful to tabulat and/or graphically rprsnt th rsults obtaind. Th sa princis of intrprting rsults and dtrining faults can b xtndd to CFD and usd in uch th sa way as with strss analysis and hat transfr. Pag 9 of 9