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The use of computational structural models that include geometrical non-linearity in many application cases may require high reliability in prediction of displacements. Nevertheless, large differences up to 60% on maximum total displacement have been found among results of static large-deformation analyses performed by means of the major commercial software packages in a simple benchmark study with linear material properties. In order to investigate the causes of such disagreement, the present work compares different finite element formulations including well-established stress update schemes. The various formulations are tested, and results are compared in three test cases. Rodriguez stress update algorithms have shown the best performance among methods reported in literature. Finally, the cause of the large differences found in the predictions of commercial codes is identified. It is linked to the energetic inconsistency of some stress update methods in the simulation of extension/compression loading conditions. Such inaccuracy is reproduced analytically by formulating and integrating the corresponding inconsistent constitutive equations. The identified problem is very important for designers, as it affects almost all the static simulations, which are the most common type of large-deformation analyses and usually involve extension/compression loading. [ABSTRACT FROM AUTHOR]

The paper presents how a robotic gripper specific for grasping and handling of textiles and soft flexible layers can be miniaturized and improved by polymeric additive manufacturing-oriented re-design. Advantages of polymeric additive manufacturing are to allow a re-design of components with integrated functions, to be cost-effective equipment for small batches production and the availability of suitable materials for many applications. The drawback is that for design validation extended testing is still necessary because of lacks in standardization and that the mechanical properties are building parameters dependent. The outcomes are a lower complexity of the design overall and lower number of components. These are pursued taking advantage of the anisotropy of the additive manufacturing processed polymer and assigning appropriate shapes and linkages in the mechanisms. Set of common materials (polylactide, polyethylene terephthalate, acrylonitrile butadiene styrene) and technical (acrylonitrile styrene acrylate, polycarbonate/polybutylene terephthalate blend) are tested to obtain data for the modelling. [ABSTRACT FROM AUTHOR]