This paper presents the structural design and analysis of a novel compliant gripper based on the Scott-Russell (SR) mechanism. The SR mechanism in combination with a parallelogram mechanism enables the achievement of a pure translation of the gripper tips, which is attractive for practical micromanipulation and microassembly applications. Unlike traditional pure-translation grippers, the reported SR-based gripper exhibits a simple structure as well as compact dimension because the in-plane space is fully used. The kinematics, statics and dynamics models of the gripper mechanism are established, and finite element analysis (FEA) simulations are carried out to verify the structure design. A prototype has been developed for experimental testing. The results not only demonstrate the feasibility of the proposed SR-based gripper design but also reveal a promising performance of the gripper when driven by piezoelectric stack actuators. Moreover, several variations of the gripper structure are presented as well.

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Purpose – The purpose of this paper is to characterize the pitting behaviour of sigma-phase-containing duplex stainless steel and investigate the correlation between magnetic susceptibility and pitting potentials. Design/methodology/approach – Use an alternating current (AC) magnetic susceptometer to trace the change in magnetic susceptibility associated with sigma phase formation and systematic study of the effects of sigma precipitation on pitting parameters as obtained using the anodic potentiodynamic polarization test. Findings – The precipitation of sigma phase impairs the general and pitting corrosion resistance of duplex stainless steel. The pitting potential, the corrosion potential and the AC magnetic susceptibility have good correlations. Unlike the pitting potential and the corrosion potential, the passive current and the corrosion current do not seem to possess any trend with annealing time. Originality/value – The correlation between AC magnetic susceptibility and pitting parameters has not been reported in the literature before.

This paper looks into the influences of martensitic transformations on the cavitation-erosion (CE) damage initiation mechanism and pitting corrosion resistance of a lean austenitic stainless steel. The ε and α' martensites are prime sites of CE damage initiation for this steel, whereas grain boundaries are more favourable damage initiation sites for other similar steels. The profusion of ε and α' results in fast surface roughening during the CE process, which may cause a compromise in performance when this steel (or similar steels that have the same CE damage mechanism) is used for such applications as hydro-machinery or piping. ε and α' also detrimentally affect the pitting resistance of this steel and so they are expected to affect CE resistance adversely due to the synergism between CE and corrosion.