In many industries, it is often required to transfer objects using compliant fingers capable of accommodating a limited range of object shapes/sizes without causing damage to the products being handled. This paper presents a coupled computational and experimental method in time domain to characterize the damping coefficient of a continuum structure, particularly, its applications for analyzing the damping effect of a highly damped compliant finger on contact-induced forces and stresses. With the aid of Rayleigh damping and explicit dynamic finite element analysis (FEA), this method relaxes several limitations of commonly used damping identification methods (such as log-decrement and half-power methods) that are valid for systems with an oscillatory response and generally estimate the damping ratio for a lumped parameter model. This damping identification method implemented using off-the-shelf commercial FEA packages has been validated by comparing results against published data; both oscillatory and nonoscillatory responses are considered. Along with a detailed discussion on practical issues commonly encountered in explicit dynamic FEA for damping identification, the effects of damping coefficients on contact between a rotating compliant finger and an elliptical object has been numerically investigated and experimentally validated. The findings offer a better understanding for improving grasper designs for applications where joint-less compliant fingers are advantageous.

We consider here a class of compliant mechanisms consisting of one or more flexible beams, the manipulation of which relies on the deflection of the flexible beams. As compared with traditional rigid-body mechanisms, compliant mechanisms have the advantages of no relative moving parts and thus involve no wear, backlash, noises, and lubrication. This paper presents a formulation based on shooting method (SM) and two numerical solvers for analyzing compliant mechanisms consisting of multiple flexible members that may be initially straight or curved. Five compliant mechanisms, which are chosen to illustrate both initially straight and curved members and different types of joint/contact conditions, are formulated to exemplify analyses using the generalized shooting method for a wide spectrum of applications. The advantages of the generalized SM over the finite difference FD and finite element FE methods are demonstrated numerically. Unlike FD or FE methods that rely on fine discretization of beam members to improve its accuracy, the generalized SM that treats the boundary value problem (BVP) as an initial value problem can achieve higher-order accuracy relatively easily, and hence is more efficient computationally. In addition, the computed results were validated experimentally. It is expected that the generalized SM presented here will offer designers a useful analysis tool, and will effectively facilitate the process of design and optimization of compliant mechanisms.

A compliant gripper gains its dextral manipulation by the flexural motion of its fingers. It is a preferable device as compared to grippers with multijoint actuations because of reduced fabrication complexity and increased structural reliability. The prediction of contact forces and deflected shape are essential to the design of a compliant finger. A formulation based on nonlinear constrained minimization is presented to analyze contact problems of compliant fingers. The deflections by flexural and shear deformations are both considered. For a planar finger, this formulation further reduces the domain of discretization by one dimension. Hence, it offers a simpler formulation and is computationally more efficient than other methods such as finite element analysis. This method is rather generic and can facilitate design analysis and optimization of compliant fingers. We illustrate some of these attractive features with two types of compliant fingers, one for object handling and the other for snap-fit assembly applications.

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