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BIOMECHANICS USING MULTIBODY DYNAMICS AND CONTACT DETECTION WITH SUPERQUADRIC SURFACES
S354
Presentation 1783 − Topic 26. Injury biomechanics
BIOMECHANICSUSINGMULTIBODYDYNAMIC SAND CONTACTDETECTIONWITHSUPERQUADRICSUR FACES Ricard do F. Portal , Luís G. So ousa, João P. P Dias
IDME EC – Institute te of Mechanical Engineering IST – Instituto Superior S Té écnico – Tec chnical Univ versity of Liisbon Av. Rovisco R Paiss, 1049-001 1 Lisbon, Po ortugal [ricarrdo.portal, ls lsousa, jdias s]@dem.ist.utl.pt This paaper presentts the resu ults from tthe implemenntation of a multibody m dynaamics code ussed in previouus works from m [Nikravesh,, 1988] with tthe methodollogy developped by the authors in tthe surface ccontact presennted in [Porttal, 2010]. T The main goaal of the multiibody dynamiics is to proviide the basiss for the stuudy of mech hanical system ms defined bby a set of boodies connecteed by kinemaatic joints. Thhe analysis off the dynamic response of tthe system uunder the acttuation of loads defined by forces annd moments acting on thee bodies and/ d/or joints muust take underr attention the surface contaact that can occur betweeen bodies. As the contaact occurs, a new set off contact forrces appears to prevent iinterpenetratioon of the bod dies in contaact. Contact detection has h fundamental role in vial assignmeent. multibodyy dynamics annd is not a triv Some technics using superquadric [Barr, 19881] ms are used to surfaces and optimizaation algorithm provide accurate ressults in the contact pooint determinaation and subssequent contacct force. The conttact detection between a pair of bodiess is formulateed as a connvex nonlineear constrainned optimizattion problem m, defining the objectiive function as the distancce between th he surfaces. T The problem constraints are a the impliccit superquaddric ween its norm mal surfaces and the paraallelism betw The vectors aat the candiddates to contaact points. T problem variables arre defined ass the cartesiian n both surfacces. coordinattes of the conntact points in The optimization algorithms a are a based on mathemaatical prograamming using Sequenttial Quadraticc Programminng (SQP) meethod, coded in FORTRA AN environmeent. This narrrow stage of tthe contact ddetection methhodology only occurs in tthe cases wheere the broadeer phase test positive. p Contact ddetection efficciency is imp proved by usiing boundingg volumes thhat improvess computationnal efficiencyy, using spheres and orieented boundiing boxes (figgure 1). The conntact force iss described by a modifiied Hertzian continuous contact mod del [Lankaraani, 1990] thaat accounts foor geometric and mechaniccal characterristics of thee surfaces in n contact. T The contact force is reepresented by b elastic aand dissipativve componentts, each of theem evaluated as function of the elasticc pseudo-peneetration betweeen the impaccting bodies. Journal of Biomechanics 45(S1)
Fiigure 1: Conta act detection bbroad phase his method was implemeented in a multibody m Th dy ynamics code, where the opptimization in nformation is used from th he previous tiime step in th he current ne. Mechaniical systems interaction can be on simulated indep pendently of iinitial estimattes for the bo odies in contact, the contaact points’ co oordinates an nd even the nu umber of conta tact points.
References R s Barr, A.: Su uperquadrics and angle-p preserving mputer Grap phics and traansformationss, IEEE Com Applications, A Vol. V 1, No. 1, ppp. 11-23, 198 81. Laankarani, H.;; Nikravesh, P.: A Conttact Force Model M with Hysteresis D Damping for Impact Analysis A of Multibody Systems, Jo ournal of Mechanical M Deesign, Vol. 1112, No. 3, pp.. 369-376, 19 990. Nikravesh, N P.: P Computeer-aided anaalysis of mechanical m sy ystems. Prent ntice-Hall, En nglewoodCliffs New Jerssey, 1988. Po ortal, R.; Sou usa, L.; Dias,, J.: Contact Detection beetween Conv vex Superquuadric Surfaaces. The Archive A of Mecchanical Enginneering, Vol. 77, No. 2, pp p. 165-186, 20 010.
ESB2012: 18th Congress of the European Society of Biomechanics
Presentation 1783 − Topic 26. Injury biomechanics
BIOMECHANICSUSINGMULTIBODYDYNAMIC SAND CONTACTDETECTIONWITHSUPERQUADRICSUR FACES Ricard do F. Portal , Luís G. So ousa, João P. P Dias
IDME EC – Institute te of Mechanical Engineering IST – Instituto Superior S Té écnico – Tec chnical Univ versity of Liisbon Av. Rovisco R Paiss, 1049-001 1 Lisbon, Po ortugal [ricarrdo.portal, ls lsousa, jdias s]@dem.ist.utl.pt This paaper presentts the resu ults from tthe implemenntation of a multibody m dynaamics code ussed in previouus works from m [Nikravesh,, 1988] with tthe methodollogy developped by the authors in tthe surface ccontact presennted in [Porttal, 2010]. T The main goaal of the multiibody dynamiics is to proviide the basiss for the stuudy of mech hanical system ms defined bby a set of boodies connecteed by kinemaatic joints. Thhe analysis off the dynamic response of tthe system uunder the acttuation of loads defined by forces annd moments acting on thee bodies and/ d/or joints muust take underr attention the surface contaact that can occur betweeen bodies. As the contaact occurs, a new set off contact forrces appears to prevent iinterpenetratioon of the bod dies in contaact. Contact detection has h fundamental role in vial assignmeent. multibodyy dynamics annd is not a triv Some technics using superquadric [Barr, 19881] ms are used to surfaces and optimizaation algorithm provide accurate ressults in the contact pooint determinaation and subssequent contacct force. The conttact detection between a pair of bodiess is formulateed as a connvex nonlineear constrainned optimizattion problem m, defining the objectiive function as the distancce between th he surfaces. T The problem constraints are a the impliccit superquaddric ween its norm mal surfaces and the paraallelism betw The vectors aat the candiddates to contaact points. T problem variables arre defined ass the cartesiian n both surfacces. coordinattes of the conntact points in The optimization algorithms a are a based on mathemaatical prograamming using Sequenttial Quadraticc Programminng (SQP) meethod, coded in FORTRA AN environmeent. This narrrow stage of tthe contact ddetection methhodology only occurs in tthe cases wheere the broadeer phase test positive. p Contact ddetection efficciency is imp proved by usiing boundingg volumes thhat improvess computationnal efficiencyy, using spheres and orieented boundiing boxes (figgure 1). The conntact force iss described by a modifiied Hertzian continuous contact mod del [Lankaraani, 1990] thaat accounts foor geometric and mechaniccal characterristics of thee surfaces in n contact. T The contact force is reepresented by b elastic aand dissipativve componentts, each of theem evaluated as function of the elasticc pseudo-peneetration betweeen the impaccting bodies. Journal of Biomechanics 45(S1)
Fiigure 1: Conta act detection bbroad phase his method was implemeented in a multibody m Th dy ynamics code, where the opptimization in nformation is used from th he previous tiime step in th he current ne. Mechaniical systems interaction can be on simulated indep pendently of iinitial estimattes for the bo odies in contact, the contaact points’ co oordinates an nd even the nu umber of conta tact points.
References R s Barr, A.: Su uperquadrics and angle-p preserving mputer Grap phics and traansformationss, IEEE Com Applications, A Vol. V 1, No. 1, ppp. 11-23, 198 81. Laankarani, H.;; Nikravesh, P.: A Conttact Force Model M with Hysteresis D Damping for Impact Analysis A of Multibody Systems, Jo ournal of Mechanical M Deesign, Vol. 1112, No. 3, pp.. 369-376, 19 990. Nikravesh, N P.: P Computeer-aided anaalysis of mechanical m sy ystems. Prent ntice-Hall, En nglewoodCliffs New Jerssey, 1988. Po ortal, R.; Sou usa, L.; Dias,, J.: Contact Detection beetween Conv vex Superquuadric Surfaaces. The Archive A of Mecchanical Enginneering, Vol. 77, No. 2, pp p. 165-186, 20 010.
ESB2012: 18th Congress of the European Society of Biomechanics