Retraction: Research on Force Analysis and Path Planning of Flexible Needle Puncture Bending Modelling (J. Phys.: Conf. Ser. 1952 042058)

This article has been retracted by the authors following an admission that this article uses work from [1] without attribution. IOP Publishing has investigated in line with the COPE guidelines, and agree the article should be retracted. The authors agree to this retraction and apologise to the original creator of the work. 1. Shi Kaiming 2019 Research on Movement Modeling and Path Planning of Flexible Cannula Needle Based on Finite Deformation Theory PhD Thesis Harbin University of Science and Technology, China (https://t.cnki.net/kcms/detail?v=zDWWPGpj7XNIYVmjPzotLQQrqE5suL8UT58pa0eYSzNWTc6cTneXhheuT3eZOa2hfsihnencE2errhffb1l--WQrpYCErNwN730qt90Gb_CdjKxkPFYC1Ppuj1cZoBQyYGNMZRph70O-WGDNoSWGdk1rtHYrxJSM&uniplatform=%20NZKPT) Retraction published: 03 December 2021

Quantifying the equilibrium swelling responses and swelling-induced snap-through of heterogeneous spherical hydrogels

We employ the finite deformation theory to analyze the inhomogeneous large deformation of a heterogeneous spherical hydrogel subjected to chemo-mechanical loadings. The heterogeneous spherical hydrogel is composed of two concentric spherical hydrogel layers with different material properties. The Gent model is employed for the free energy function of the polymer stretching part in order to tackle the effect of the limiting chain extensibility. The heterogeneous spherical hydrogel is assumed to be perfectly bonded at the interface and is traction free at the external surface. At the internal surface, two boundary conditions are considered: one is internally fixed and the other is internally pressurized. Numerical examples are performed to describe the nonlinear behaviors of a heterogeneous spherical hydrogel when subjected to the swelling and mechanical loadings. For internally fixed case, numerical results show that the limiting chain extensibility and the initial swelling ratio have significant effect on the actuation deformation of a heterogeneous spherical hydrogel. For internally pressurized case, we find that the swelling-induced snap-through instability can be triggered under specified conditions. It is shown that the chemo-mechanical behaviors of the heterogeneous spherical hydrogels can be adjusted by tuning the material properties and the initial swelling ratios.

Pure shear deformation and its induced mechanical responses in metallic glasses

Shear is a basic deformation mode governing yielding, plasticity and fracture in metallic solids. For amorphous metals, due to various constraints, little work is available in addressing directly shear deformation and shear-induced mechanical property changes which are vital to the mechanistic understanding of this new class of disordered materials. Here, by using a finite deformation theory, we examine the pure shear deformation in a bulk metallic glass in a large range of shear strains. With the continuum approach, we show systematically for the first time the detailed shear deformation behaviours, shear-induced normal stress and strain relations, softening in the elastic constants, volume dilatation and free energy change induced by the shear deformation. These results point to two major consequences from the shear deformation, one is the mechanical degradations and the other material degradation which is responsible for the changes in the mechanical properties of the disordered materials.

Meshfree Method for Geometrical Nonlinear Analysis of Curved and Twisted Beams Using a Three-Dimensional Finite Deformation Theory

This paper presents a three-dimensional finite deformation theory for the geometric nonlinear analysis of both the curved and twisted beams using the meshfree method based on the Timoshenko beam hypothesis. The theory presented is simple, but it is capable of solving the stability, postbuckling, snap-through, and large deformation problems effectively. Clear physical meanings will be revealed in derivation of the three-dimensional finite deformation theory. A meshfree method based on the differential reproducing kernel (DRK) approximation collocation method combined with the Newton–Raphson method is employed to solve the strong forms of the geometrically nonlinear problems. Numerical examples are given to illustrate the validity of the method presented.

A finite deformation theory of desolvation and swelling in partially photo-cross-linked polymer networks for 3D/4D printing applications

A finite deformation model is developed to describe desolvation and swelling in partially photo-crosslinked polymers.