An efficient ABAQUS solid shell element implementation for low velocity impact analysis of FGM plates

This study is focusing on the finite element simulation of low velocity impact applied to glass fiber-reinforced composites. Elasto-visco-plasticity is adopted taking into account strain rate effect, with isotropic hardening. To avoid numerical locking, hexahedral solid shell finite element SS is developed. The formulation is based on the mixed Assumed Natural Strain (ANS) and the Enhanced Assumed Strain (EAS) methods. A geometrical non linear condition is applied. The finite element is implemented in UEL subroutine via the commercial software ABAQUS/Standard. The numerical element proved its efficiency comparing to conventional element and previous experimental results in (Mars et al. 2018). Numerical simulations with solid element are conducted using Abaqus/standard via user material UMAT subroutine. In terms of computation time, the solid shell element is less time consuming when comparing to conventional solid element. This is due to the fact that a single element through the thickness direction is adopted. Element efficiency is assessed for various fibers contents.

Hygro-thermo-mechanical modeling of thin-walled photovoltaic laminates with polymeric interfaces

On the comparison of two solid-shell formulations based on in-plane reduced and full integration schemes in linear and non-linear applications

On the use of a reduced enhanced solid-shell (RESS) element for sheet forming simulations

Three-dimensional thermal buckling analysis of functionally graded material structures using a modified FSDT-based solid-shell element

The phase field (PF) approach to fracture has emerged as a promising modeling tool that regularizes the variational fracture theory by Griffith via the introduction of a nonlocal damage-like field variable in the corresponding formulation. In this work, we outline a PF formulation for triggering brittle fracture phenomena in shell structures made of Functionally Graded Materials (FGMs). This model relies on the 6-parameter shell formulation complying with a solid shell kinematic description and incorporates the use of the Enhanced Assumed Strain (EAS) and Assumed Natural Strain (ANS) methods in order to alleviate different locking pathologies. The corresponding multi-field variational formalisms is consistently derived and discretized within the context of the Finite Element Method (FEM). Details regarding the implementation in the general purpose FE packages are outlined. The applicability of this model is demonstrated by means of several numerical applications.

In this paper, we present an optimal low-order accurate piezoelectric solid-shell element formulation to model active composite shell structures that can undergo large deformation and large overall motion. This element has only displacement and electric degrees of freedom (dofs), with no rotational dofs, and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out-of-plane bending). The combination of the present optimal piezoelectric solid-shell element and the optimal solid-shell element previously developed allows for efficient and accurate analyses of large deformable composite multilayer shell structures with piezoelectric layers. To make the 3-D analysis of active composite shells containing discrete piezoelectric sensors and actuators even more efficient, the composite solid-shell element is further developed here. Based on the mixed Fraeijs de Veubeke–Hu–Washizu (FHW) variational principle, the in-plane and out-of-plane bending behaviours are improved via a new and efficient enhancement of the strain tensor. Shear-locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. We also present an optimal-control design for vibration suppression of a large deformable structure based on the general finite element approach. The linear-quadratic regulator control scheme with output feedback is used as a control law on the basis of the state space model of the system. Numerical examples involving static analyses and dynamic analyses of active shell structures having a large range of element aspect ratios are presented. Active vibration control of a composite multilayer shell with distributed piezoelectric sensors and actuators is performed to test the present element and the control design procedure. Copyright © 2005 John Wiley & Sons, Ltd.

In this paper, the structure of cylindrical shell with a reinforced circular cutout using combination model of solid element and shell element was analyzed by Finite Element Method (FEM) simulations. Multipoint constraint (MPC) method is mainly used to solve the connection between solid element and shell element when considering the calculation accuracy and efficiency of the model. The combination model of solid and shell element is established in ANSYS, and has been compared to the model of shell element and the model of solid element. The result showed that in the aspects of the stress distribution of the pressure hull near the cutout, buckling behavior of the structure and its instability response, the combination model of solid and shell element was almost equal to the others, it is convincible as well as possessing merits of other models.

The principle of robot based incremental sheet metal forming is based on flexible shaping by means of a freely programmable path-synchronous movement of two tools, which are operated by two industrial robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the geometry’s contour in lateral direction. The main problem during the forming process is the influence on the dimensional accuracy resulting from the compliance of the involved machine structures and the springback effects of the workpiece. The project aims to predict these deviations caused by resiliences and to carry out a compensative path planning based on this prediction. Therefore a planning tool is implemented which compensates the robot’s compliance and the springback effects of the sheet metal. Finite element analysis using a material model developed at the Institute of Applied Mechanics (IFAM) [1] has been used for the simulation of the forming process. The finite strain constitutive model combines nonlinear kinematic and isotropic hardening and is derived in a thermodynamical setting. It is based on the multiplicative split of the deformation gradient in the context of hyperelasticity. The kinematic hardening component represents a continuum extension of the classical rheological model of Armstrong–Frederick kinematic hardening which is widely adopted as capable of representing the above metal hardening effects. The major problem of low-order finite elements used to simulate thin sheet structures, such as used for the experiments, is locking, a non-physical stiffening effect. Recent research focuses on the large deformation version of a new eight-node solid-shell finite element based on reduced integration with hourglass stabilization. In the solid-shell formulation developed at IFAM ([2], [3]) the enhanced assumed strain (EAS) concept as well as the assumed natural strain (ANS) concept are implemented to circumvent locking. These tools are very important to obtain a good correlation between experiment and simulation.

The paper deals with the validation of a recently proposed hexahedral solid-shell finite element in the buckling analysis of a laminated composite plate with delaminations. The object is to study the buckling behavior of structures with delaminations using the enhanced assumed strain (EAS) solid shell element with 5, 7 and 9 parameters. The EAS three-dimensional finite element formulation presented in this paper is free from shear locking and leads to accurate results for distorted element shapes. The developed FE model is used to study the effects of some parameters in the buckling load, such as the stacking sequences, delamination size, aspect ratio, width-to-thickness ratio. The feasibility of the proposed method is confirmed by numerical examples. Results show that using hexahedral solid-shell finite element in the buckling analysis is more efficient than using the enhanced solid finite element.

The parametrization of shell structures using the so-called solid shell concept has been widely exploited in the last decades. This trend is mainly attributed to the relatively simple kinematic treatment of solid shells in the corresponding finite element formulation in conjunction with the use of unmodified three-dimensional material laws, among other aspects. In the present investigation, we provide a comprehensive finite element implementation of solid shells incorporating: (i) the use of Enhanced Assumed Strain (EAS) and the Assumed Natural Strain (ANS) methods to prevent locking issues, (ii) the phase-field approach for triggering fracture events, and (iii) some representative inelastic material models. The current modular implementation has been integrated into the FE package ABAQUS via the user-defined routine UEL. Several representative examples demonstrate the applicability of the present formulation.

Nonlinear numerical dissipative elastodynamics of an optimal solid shell element

摘要: 研究矩形截面功能梯度材料(Functionally graded materials, FGM)梁在不同剪切变形理论下的静力弯曲问题。假设FGM梁由金属和陶瓷两种材料构成,其等效物性参数沿厚度方向连续变化,且遵从简单幂率变化规律。基于最小势能原理,建立以轴向位移、横向位移及转角为未知函数的FGM梁的运动微分方程组。对简支FGM梁,采用Fourier级数法获得5种剪切变形理论下FGM梁的挠度、轴向位移及转角曲线,分析梁的长高比、梯度指标对弯曲变形的影响,分析不同剪切变形理论下FGM梁的切应力和正应力的分布特性,并与均质材料梁的静力弯曲特性进行比较。给出FGM梁的中性轴位置随梯度指标的变化曲线并进行分析。

The vibration of beams carrying uniform moving distributed masses is investigated in this paper. A finite element (FEM) based on the first shear deformation theory (FSDT) is assumed for the beam model. A ten degree of freedom beam element for the FSDT theory is considered. Combination of the element property matrices for moving mass and the associated overall property matrices for the beam determines the overall effective property matrices of the entire system. The equations of motion are integrated by applying the Newmark’s procedures to obtain the system responses. The numerical results of vibration of beams are presented and, whenever possible, compared to the available results in order to demonstrate the accuracy of the present method. Effect of the Coriolis and centrifugal forces induced by the moving distributed mass are investigated. Numerical results reveal that all above mentioned parameters have significant influence on dynamic responses of inclined beams.

Concerning, higher-order shear deformation theories (HSDT) for composite plates, this article presents a numerical investigation on local characteristics (distribution along the plate thickness of in-plane displacement, in-plane normal stress, and transverse shear stress component;) in the large-deflection and postbuckling fields. The von Kdrmdn theory in conjunction with a recent mixed two-dimensional model, elsewhere denoted by the acronym RMZC (Reissner-Mindlin zigzag continuity) is employed. The RAfZC model assumes two independent fields along the plate thickness for displacements and transverse shear stresses, respectively; the displacement model describes the so-called zigzag form for the in-plane components, while the stress field fulfils interlaminar equilibria. Standard displacement formulation is enforced by employing variationalty consistent constitutive equations between stress and displacement unknowns. Finite-element-type approximations are introduced on the plate domain, leading to governing equations in the form of a nonlinear system of algebraic equations. This is solved through application of the Newton-Raphson method accounting for arc-length strategies. Explicit forms of the linear and nonlinear resulting matrices are quoted in appendixes. The numerical investigation and discussion concern large-deflection and postbuckling analysis of symmetrically laminate square thick/thin plates subjected to simply supported and clamped boundary conditions. Results of the RMZC model are compared with those related to CLT classical lamination theory (CLT) and first shear deformation theory (FSDT). It has been confirmed that the importance of effects related to the RMZC model are more evident when local characteristics are described. Furthermore, it has been found that such effects become more significant when large deflections as well as postbuckled equilibrium states of thick plates are considered, while for the thin-plate analyses, FSDT and RMZC have furnished very close results.