Assessment on assorted hyper-elastic material models applied for large deformation soft finger contact problems
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Assessment on assorted hyper-elastic material models applied for large deformation soft finger contact problems K. Venkatesh Raja • R. Malayalamurthi
Received: 22 June 2011 / Accepted: 29 July 2011 / Published online: 7 August 2011 Ó Springer Science+Business Media, B.V. 2011
Abstract Modeling of soft finger contact mechanics is a prerequisite for gripper design. Realism of soft finger deformations depends extremely on the selection of appropriate hyper-elastic material model for soft materials. The essential criterion for a good mathematical model for hyper elasticity is its ability to match the measured strain energy curves under different deformations over a large range. Selecting an appropriate material law for a given material combination is one of the most difficult tasks in soft finger contact modeling. The present study is devoted for comparing seven popular hyper-elastic non-linear material models (Mooney–Rivlin, Ogden, Yeoh, Neo-Hookean, Gent, Polynomial and Aruda–Boyce model) and selection of the most appropriate model based on experimental data for modeling of soft contact problems. Present results clearly reveal that Ogden and Neo-Hookean model are more suitable for these problems and in line with the experimental results. Finite element technique is employed for critical comparison of various hyperelastic material models.
K. Venkatesh Raja (&) Department of Automobile Engineering, K.S.R. College of Engineering, Tiruchengode 637215, Tamil Nadu, India e-mail: [email protected] R. Malayalamurthi Department of Mechanical Engineering, Govt. College of Engineering, Salem 636011, Tamil Nadu, India
Keywords Hyper-elastic Soft-finger Contact-mechanics FEA List of symbols a Contact radius c Proportionality constant ! Constant that varies from 0 to 1/3 W Strain energy function I1, I2, I3 Strain invariant k1 k2 k3 Principal stretch ratios C Material constant l Initial shear modulus of the material d Incompressibility parameter
1 Introduction Soft finger contact mechanics plays an important role in grasping stability as well as safe object prehension and handling during manipulation. Understanding how dynamic deformations arises near the contact region when a finger makes tactile contact with an object is of considerable interest in the area of robotic Engineering field. Unlike rigid fingers, soft fingers conform to the object which improves the stability of grasping. The estimation of optimal grasping forces requires knowledge of contact characteristics, including relationship between normal force and contact area, and pressure distribution profile at the finger object interface. Realistic modeling of contact for
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K. Venkatesh Raja, R. Malayalamurthi
anthropomorphic soft fingers in grasping and manipulation plays a significant role in robotics. However, contact mechanics is not a very new area for investigation. Hertz initiated studies on contact mechanics in 1882, based on contact between two linear elastic materials (Hertz 1882). He also conducted experiments using glass, and found
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