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The present paper presents a comprehensive study based on numerical and experimental investigations testing the use of NC lathe machine in SPIF process of a dome part made of AA1060-H14 aluminum alloy. The main idea is to check the viability of NC turning machine in SPIF process of axisymmetric parts usually manufactured using 3-axis milling machines. For this purpose, aluminum thin sheet is firstly characterized and the right material behavior is identified. A VUMAT subroutine is used to implement this material behavior in ABAQUS/explicit FE used to simulate the SPIF-Turning operation. A comparison between experimental and numerical results showed the efficiency of this FE model to simulate a 2-axis SPIF strategy. Results, covering forming effort, thinning, the strain state distribution, fracture occurrence, and surface finish proved that NC turning machines could manufacture rapidly and with more accuracy, revolved components usually formed by a 3-axis NC milling machine.

The main purpose of this study is to develop a variational formulation for predicting structure behavior and accounting for damage mechanics in metallic materials. Mechanical and coupled thermomechanical models are used to predict failure in manufacturing processes. Ductile failure is accompanied by a significant amount of plastic deformation in metallic structural components. Finite element simulation of damage evolution in ductile solids is presented in this paper. Uncoupled models are implemented in a finite element model simulating deep drawing as well as cutting processes. Based on the Johnson–Cook model, the effect of deformation on the evolution of flow stress is described. The combined effect of strain, strain rate, and temperature on plasticity and damage behavior in cutting processes is considered. The accuracy of these models is verified when predicting ductile damage in forming and cutting processes.

Recent research has focused on sheet shear cutting operations. However, little research has been conducted on bar shear cutting. The main objective of the present investigation is to study bar shear cutting with numerical and experimental analysis. Bar shear cutting is an important operation because it precedes bulk metalworking processes for instance machining, extrusion and hot forging. In comparison to sheet shear cutting, bar shear cutting needs thermomechanical modelling. The variational formulation of the model is presented to predict damage mechanics in the bar shear cutting of aluminium alloys. Coupled thermomechanical modelling is required to analyse the mechanical behaviour of bulk workpieces, in which the combined effect of strain and temperature fields is considered in the shear cutting process. For this purpose, modified hardening and damage Johnson–Cook laws are developed. Numerical results for sheet and bar shear cutting operations are presented. The comparison between numerical and experimental results of shearing force/tool displacement during sheet and bar shear cutting operations proves that the use of a thermomechanical model in the case of the bar shear cutting process is crucial to accurately predict the mechanical behaviour of aluminium alloys. The analysis of the temperature field in the metal bar shows that the temperature can reach T = 388 °C on the sheared surface. The current model accurately predicts the shear cutting process and shows a strong correlation with experimental tests. Two values of clearance (c1 = 0.2 mm) and (c2 = 1.2 mm) are assumed for modeling the bar shear cutting operation. It is observed that for the low shear clearance, the burr is small, the quality of the sheared surface is better, and the fractured zone is negligible.

The main objective of this study was to investigate the influence of implant geometrical characteristics: diameter, length and thread's pitch, on stress distribution around dental prosthesis. A set of numerical simulations using FEM were conducted and responses surfaces were generated. With the aim of optimizing the equivalent stresses responses; desirability function approach was adopted to solve this multi-objective problem. Results showed that implant diameter had most significant influence on generated stresses and high concentration of stresses were identified in the lower part of the implant. This study is helpful in choosing the optimal dental implant for clinical application.

NiTi wires are considered as the most appropriate wires to be used during the initial phase of orthodontic treatment. This work presents a numerical method to simulate the coupling between the orthodontic appliance and bone remodeling, which are the two mechanisms responsible for the orthodontic tooth movement.The superelastic behavior of a NiTi wire was integrated in a three-dimensional simulation model to reproduce the long-term bone remodeling coupled with tooth alignment using the finite element method. The orthodontic load was derived by deforming the superelastic wire in order to adopt itself to the original position of irregular teeth. Root form was extracted from cone beam tomography imaging files.As a result, the teeth were aligned while the wire was recovering its initial shape. The canine was intruded by 0.53 mm, while the neighboring teeth were extruded by 0.44 and 0.46 mm. When the wire was loaded, it generated a load of 4.6 N on the bracket bonded on the canine. This force was active during the first day of the treatment. Then, the force continued to decline until the end of the correction period. The decreasing load delivered from the wire affected the teeth displacements as observed in real situations.Despite the complexity of the presented numerical simulation, this procedure allowed the analysis of the orthodontic forces that were generated in the clinical experiments and of the biomechanical response of the periodontal support elements when using this kind of wire.ZIELSETZUNG: NiTi-Drähte gelten als die für die Anfangsphase einer kieferorthopädischen Behandlung am besten geeigneten Drähte. In der vorliegenden Arbeit wird eine numerische Methode vorgestellt, um die Verbindung zwischen kieferorthopädischer Apparatur und Knochenumbau zu simulieren – die beiden für die kieferorthopädische Zahnbewegung verantwortlichen Faktoren.Das superelastische Verhalten eines NiTi-Drahtes wurde in ein dreidimensionales Simulationsmodell integriert, um den langfristigen Knochenumbau in Verbindung mit der Zahnausrichtung unter Verwendung der Finite-Elemente-Methode zu reproduzieren. Die kieferorthopädische Belastung wurde abgeleitet, indem der superelastische Draht so verformt wurde, dass er sich an die ursprüngliche Position unregelmäßiger Zähne anpasst. Die Wurzelform wurde aus den DVT(digitale Volumentomographie)-Bilddateien extrahiert.Im Ergebnis wurden die Zähne ausgerichtet, während der Draht wieder seine ursprüngliche Form annahm. Der Eckzahn wurde um 0,53 mm intrudiert, die benachbarten Zähne wurden um 0,44 und 0,46 mm extrudiert. Der aktivierte Draht erreichte eine Kraft von 4,6 N auf das am Eckzahn angebrachte Bracket. Diese Kraft war am ersten Tag der Behandlung wirksam, im Anschluss wurde sie bis zum Ende der Behandlungszeit kontinuierlich geringer. Die nachlassende vom Draht ausgehende Kraft beeinflusste die Zahnverschiebungen, wie dies in der Praxis zu beobachten ist.Trotz der Komplexität der numerischen Simulation ermöglichte das vorgestellte Verfahren die Analyse der in klinischen Experimenten erzeugten kieferorthopädischen Kräfte und der biomechanischen Reaktion des parodontalen Halteapparates bei der Verwendung dieser Art von Draht.

This study conducts the first-known free vibration analysis of functionally graded carbon nanotubes-reinforced (FG-CNTRC) shell structures using the meshfree radial point interpolation method (RPIM). The modified first-order shear deformation theory (modified FSDT) is implemented to get the realistic effect of the transverse shear deformation with its parabolic distribution. Numerical examples are carried out to examine the convergence and accuracy of the element-free RPIM method in its application to the free vibration FG-CNTRC analysis of shell structures. Results obtained using the proposed meshfree method, demonstrate that the improved FSDT is very successful compared to closed-form solutions and finite element results using different shell theories.

The present paper presents numerical and experimental comparative studies between the conventional bending process (bending using punch and V-die) and bending with a rubber-pad cushion. In fact, a finite-element method is introduced to compare these two procedures used to bend AA1050-H14 Aluminum thin sheet. An elastoplastic constitutive model with quadratic yield criterion of Hill 48 and isotropic hardening behavior has been adopted in FE simulations performed using ABAQUS explicit. To model rubber material, a Mooney–Rivlin theory is used in the finite-element simulation. The purpose of this study is to see the difference between the two methods in terms of effort evolution, springback, stress distribution, thinning. Analyze the effect of the rubber material; in fact, natural rubber, and polyurethane with hardness 50, 70, and 90 shore A are investigated. This numerical study was validated by an experimental investigation that proved the efficiency of the elastic cushion to bend in a better way this thin aluminum sheet.

As a new kind of composite materials, functionally graded (FG) composite material has been introduced to solve numerous practical problem arisen from several applications. Further, in various engineering applications FGM structures can undergo major displacements and withstand significant deformations and large rotations. The goal of this paper is to conduct nonlinear investigation of ceramic/metal FG beam. In this purpose, a user-defined subroutine (UMAT) is created in Abaqus/Standard. The non-linear feedback of the FG beam is supposed elastoplastic based on the isotropic hardening (Ludwik hardening law). The calculation of the effective material properties is based on the Mori–Tanaka scheme as well as self-consistent approach of Suquet. Elastoplastic material properties are evaluated and supposed to change softly over the thickness of the beam. Numerical results obtained show the effect of material allocation on nonlinear responses. It was revealed that power index has a meaningful impact on the nonlinear reply of the FG cantilever subjected to end moment.

Development of new materials such as functionally graded material FGM for dental implant applications have been recently received significant attention due to their abilities to satisfy both biocompatibility and mechanical properties simultaneously. The goal of this research is to evaluate the influence of implant diameter dimension on stress distribution around dental prosthesis. For this purpose, an axisymmetric finite element model of the implant and the jaw bone is constructed. The finite element model of implant, cortical bone and cancellous bone is constructed in Abaqus software. The implant body is made of FGM, which is a mixture of titanium (Ti) and hydroxyapatite (HAP). The implant diameter varied as different values so according to material properties of FGM and implant diameter dimension, stress distribution are investigated. Functionally graded material are used to reduce stress concentration in implant, trabecular and cortical bones and to improve biocompatibility.

Hole-flanging process is widely being used in metal forming industry. Using elastomeric punch instead of the rigid one may enhance the quality of surface finish of the produced part. The objective of this paper is to investigate the sheet metal hole-flanging process with soft punch. This investigation is carried out via numerical and experimental analysis using polyurethane rubber with hemispherical end as flexible tool. Material of workpiece is the aluminum AA 1050-H14. Numerical simulation of the flexible hole-flanging process is performed with Abaqus/ Explicit. A Mooney-Rivlin model is adopted to predict the hyperelastic parameters of rubber punch with Shore hardness 70 A. The Coulomb friction law is adopted to model the contact between soft punch/part and part/rigid die. An experimental set up is developed to produce flanges. Numerical result presents a comparison between classical hole-flanging process with rigid tool and flexible process with rubber tool in term of variation of thickness distribution along the flange wall. Using soft tool with hemispherical end may improve the formability of aluminum flanged part compared to conventional forming technique. Numerical prediction of thickness distribution is assessed with the experimental measurement along the wall of the flanged part for validation purpose.

Rubber materials are increasingly used in automotive and aircraft manufacturers companies because their advantages in terms of corrosion resistance, vibration isolation and impact. These materials exhibit the proprieties of hyperelastic and viscoelastic materials where their mechanical proprieties depend on time variation, when subjected to mechanical load. The purpose of this work is to identify the hyper-viscoelastic parameters of polyurethane, natural and silicone rubber (Shore hardness 70 A and 90 A). These three materials are the most popular materials used as flexible punch or soft die in sheet metal forming process. The three specimens were prepared according to the ASTM D575-91 (2018). Standard compression and stress relaxation tests were performed to obtain experimental stress-strain curves of different rubber specimens. These curves were fitting with four model (Mooney Rivlin 1940, Neo-Hookean 1943, Ogden 1972, Yeoh 1993), available in ABAQUS to estimate the hyperelastic parameters of each model. These hyperelastic models are widely used in prediction the hyperelastic behavior of elastomeric material. For viscoelasticity, through the use of Prony series method, parameters are identified from fitting of relaxation curves. Ogden and Mooney Rivlin rubber models are well suited to reproduce experimental stress-strain curves of given rubber comparing to Neo Hooke and Yeoh models.

This research makes a first attempt to investigate the dynamic characteristics of functionally graded carbon nanotube–reinforced composite plates and shell structures with surface-bonded piezoelectric layers. A variational formulation is derived based on the linear double director shell theory to ensure realistic parabolic variation of transverse shear strain along the thickness direction. The assumed natural strains method is adopted to enhance the accuracy of the four-node piezoelectric shell element developed in this study. Numerical studies are conducted to validate the efficiency and numerical stability of the proposed model to predict the behavior of piezolaminated composite shell structures. Furthermore, dynamic responses are extended to functionally graded carbon nanotube–reinforced composite shells covered by two active layers. The host structure is reinforced by single-walled carbon nanotubes, which are assumed to be graded through the thickness direction with different types of distributions and embedded in a polymer matrix. The effect of the volume fractions, distribution type, and geometrical parameters of the carbon nanotubes is examined.

In the present work, a geometrically nonlinear finite shell element is first presented to predict nonlinear dynamic behavior of piezolaminated functionally graded carbon nanotube-reinforced composite (FG-CNTRC) shell, to enrich the existing research results on FG-CNTRC structures. The governing equations are developed via an improved first-order shear deformation theory (FSDT), in which a parabolic distribution of the transverse shear strains across the shell thickness is assumed and a zero condition of the transverse shear stresses on the top and bottom surfaces is imposed. Using a micro-mechanical model on the foundation of the developed rule of mixture, the effective material properties of the FG-CNTRC structures, which are strengthened by single-walled carbon nanotubes (SWCNTs), are scrutinized. The effectiveness of the present method is demonstrated by validating the obtained results against those of other studies from literature considering shell structures. Furthermore, some novel numerical results, including the nonlinear transient deflection of smart FG-CNTRC spherical and cylindrical shells, will be presented and can be considered for future structure design.

Purpose This paper aims to study the static behavior of carbon nanotubes (CNTs) reinforced functionally graded shells using an efficient solid-shell element with parabolic transverse shear strain. Four different types of reinforcement along the thickness are considered. Design/methodology/approach Furthermore, the developed solid-shell element allows an efficient and accurate analysis of CNT-reinforced functionally graded shells under linear static conditions. Findings The validity and accuracy of the developed solid-shell element are illustrated through the solution of deflection and stress distribution problems of shell structures taken from the literature. The influences of some geometrical and material parameters on the static behavior of shell structures are discussed. Originality/value The finite element formulation is based on a modified first-order enhanced solid-shell element formulation with an imposed parabolic shear strain distribution through the shell thickness in the compatible strain part. This formulation guarantees a zero transverse shear stress on the top and bottom surfaces of the shell and the shear correction factors is no longer needed.

In the present paper, as a first endeavor, homogenization of elasto-plastic functionally graded material (FGM) is investigated based on representative volume element (RVE) and used for the first time in the single point incremental forming (SPIF) process. The effective properties of elasto-plastic spheres-reinforced FGM composite are determined using the numerical RVE method and Mori-Tanaka model. In order to implement the homogenization equations and numerical algorithm into Abaqus Software, user-defined material, (VUMAT) and (VUSFLD) subroutines are employed. The accuracy of the proposed homogenization methodology is highlighted through comparisons of the present results with those taken from the literature and an excellent agreement is found. During SPIF process, the effect of the power-law index on the formability, plastic deformation, forming force along Z_direction and Von Mises distribution is analyzed. Parametric studies are conducted to show the influence of cone wall angle and sheet thickness on the formability and the thinning along the SPIF process.

This paper presents an implementation of a fully coupled non-associated anisotropic plasticity-ductile damage model, including a mixed nonlinear isotropic- kinematic hardening. With the non-associated anisotropic plasticity assumption, the yielding and plastic potential are determined independently. The quadratic Hill’48 function is considered for yield and plastic potential to describe the anisotropic plastic behavior of DD13 sheets. A three non-linear local scalar equation problem is solved using the Newton–Raphson method. The numerical resolution of the proposed algorithm is implemented into ABAQUS using the user interface material subroutines (UMAT and VUMAT). A consistent tangent operator is developed to preserve the quadratic rate of asymptotic convergence that characterizes Newton's method. The evaluation of the proposed implementation ability to predict the real behavior of DD13 steel material during forming is achieved using some experimental setups performed by the authors.

The purpose of this manuscript is to carry out an experimental and numerical investigation of bulging process of aluminum AA1050-H14 sheet metal in free expansion when using a flexible punch. Three types of rubber with different hardness are used as flexible punch. First, a mechanical characterization and identification of aluminum sheet metal and polyurethane rubber parameters is achieved for validation purpose. Then, an experimental study of flexible bulging process is performed to analyze the effect of rubber type and hardness on forming capability. The obtained results show that the polyurethane with hardness of 70 Shore A is considered as the most suitable punch for the bulging operation when comparing with silicone and natural rubber. Finally, a comparison between bulging with flexible and rigid punches is conducted using the finite element code ABAQUS/Explicit. The developed simulations predict efficiently the realistic thickness distribution along the bulged part.

This paper presents a modified first-order enhanced solid-shell element formulation with an imposed parabolic shear strain distribution through the shell thickness in the compatible strain part. Moreover, zero transverse shear stress on the top and bottom surfaces of the shell is satisfied exactly and the shear correction factors is no longer needed. Furthermore, the developed solid-shell element allows an efficient and accurate analysis of functionally graded material shells under geometric nonlinear static conditions. A simple power-law functionally graded distribution of the shells along the thickness direction is considered. The validity and accuracy of the developed solid-shell element are illustrated through the solution of several known problems taken from the literature. The influences of power-law index on the nonlinear static behavior of the FGM shells are discussed.

This work makes a first attempt to conduct a geometrically non-linear analysis of functionally graded carbon nanotube reinforced composites (FG-CNTRC) structures, with surface-bonded active layers, based on Kirchhoff shell theory. Uniform and three different distribution types of functionally graded nanocomposites are presented. These distributions are assumed to be uniaxially aligned in the axial direction and functionally graded in the shell thickness direction, while the electric potential through the thickness of the active layers is assumed to be linear. A comparison study is carried out in order to show the applicability of the current formulation applied to various shapes of shell structures . The effects of various parameters as volume fraction, distribution of nanotubes , geometrical characteristics as well as load boundary on non-linear behavior of the smart FG-CNTRC structures are investigated.

The purpose of the paper is to predict the electromechanical behavior of composite shell structures with embedded piezoelectric layers using 3D-shell model based on a discrete double directors shell element. The implementation is applicable to the analysis of isotropic and functionally graded shells with integrated piezoelectric layers. The third-order shear deformation theory is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The present results were compared with reference solutions from literature in order to verify the accuracy of the present formulation and excellent agreement was found. A parametric study is carried out to highlight the influence of material composition and curvature radius on the deflection and axial stress along the thickness.

A meshfree analysis of arbitrary 3D-model based on a double directors shell model is first investigated in this paper. The high order shear deformation theory is implemented in the present work in order to remove the shear correction coefficient. The radial point interpolation method is used in the construction of shape functions based on arbitrarily distributed nodes of general spatial shell geometry. Discrete system of equations is obtained by incorporating these interpolations into the weak form. The formulation is tested on several benchmark problems considering isotropic and functionally graded spatial shell structures. Numerical tests show that the method is reliable, robust and produces accurate results compared to closed-form solutions and finite element results. The effect of the material distribution on the deflections and stresses is analyzed.

This article investigates geometrically nonlinear and linear analysis of multilayered shells with integrated piezoelectric materials. An efficient nonlinear shell element is developed to solve piezoelastic response of laminated structure with embedded piezoelectric actuators and sensors. A modified first-order shear deformation theory is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The electric potential is assumed to be a linear function through the thickness of each active sub-layer. Several numerical tests for different piezolaminated geometries are conducted to highlight the reliability and efficiency of the proposed implementation in linear and geometrically nonlinear finite element analysis.

A meshless implementation of arbitrary 3D-shell structures based on a modified first order shear deformation theory (FSDT) is investigated in this paper. The FSDT is improved in this manuscript in order to assume a parabolic distribution of the shear strain to correct the constant shear stress in the Mindlin–Reissner theory and to get closer to a realistic distribution of the shear strain through the thickness. The radial point interpolation method is used in the construction of shape functions based on arbitrarily distributed nodes of general spatial shell geometry. The convergence of the proposed model is compared to other well-known formulations found in the literature considering isotropic and functionally graded spatial shell structures. The results obtained using the proposed meshless method demonstrate that the improved FSDT is very successful compared to closed-form solutions and finite element results using different shell theories. The effect of the material distribution on the deflections and stresses is also analyzed.

In this paper, an improved anisotropic elasto-plastic model strongly coupled with isotropic ductile damage is investigated. The quadratic Hill’48 yield criterion and non-linear isotropic/kinematic hardening are considered in the associated flow rule model. The numerical formulation of the proposed model is implemented in ABAQUS finite element code via the user material subroutines UMAT and VUMAT. The mechanical behavior of DD13 sheet metal is investigated. Its significant deep drawing capability makes this material attractive, particularly for the automotive industry. An experimental database of the DD13 mechanical properties is achieved through a serie of uniaxial tensile tests, so that the anisotropic coefficients, hardening and damage parameters are obtained. For validation purpose, the numerical results are compared to Erichsen cupping test. The combined experimental/numerical study proves the ability of the proposed model in the description of the DD13 damaged-anisotropic behavior with good accuracy.

Short glass fiber reinforced thermoplastic materials exhibit visco-hyperelastic behavior which can be analyzed using different techniques such as instrumented indentation and dynamic mechanical analysis. In the present study, the mechanical response of polyamide (PA) as matrix reinforced by different ratio of glass fiber is studied experimentally and numerically. Force-displacement curves of composite materials are obtained through uniaxial tensile test. Moreover, as viscoelastic behavior takes place due to deviation from static deformation, stress relaxation test is investigated to give a good deal of information about the time dependence of the material’s behavior. Then, a visco-hyperelastic constitutive model is proposed for the behavior of these orthotropic incompressible fiber-reinforced polymer composites. The experimental data are fit in order to obtain the unknown adjustable parameters in constitutive equations using available model in commercial FEM soft-ware, such as ABAQUS. A good agreement is shown between the experimental and numerical results for all compositions. Therefore, it can be noted that the adapted model can accurately predict the nonlinear behavior of molded composites.

Dental implant have important role in restoration of damaged or lost teeth, but some problem is found in their utilization. In fact, the chewing forces are applied directly in the bone system, which necessitates studying the relationship between the stress distributions and the characteristics of dental implant near bone system interface and dental implant. Recently functionally graded materials FGM play an important role on dental clinical implant application thanks to their abilities and advantages of their mechanical properties. The objective of this study is to focus on mechanical properties of FGM denal implant in order to investigate the effect of the material gradient index on the stress distribution around dental prosthesis. The FGM properties change gradually from titanium (Ti) to hydroxyapatite (HAP). The implant body is subjected to an axial load to simulate masticatory forces. The effect of FGM properties on reduction of stress distributions in the implant-prosthesis components are highlighted.

ISF process is a promising flexible process that attracts several researches during the last decade. Applied on a CNC machine thin sheet are shaped through incremental plastic deformation trigged by a tool path programmed with a G-Code. This paper presents an experimental investigation on Single Point Incremental Forming applied on NC turning machine to manufacture revolved parts made of AA1050-H14 material. The idea is to use a 2-axis tool path strategy through the program of a paraxial roughing cycle used in machining to bore cylindrical parts. In fact, using this program, sheet metal can be shaped by incremental plastic deformation to the desired part. The effect of penetration increment, the shape of the final part on formability, appearance of cracks and the part finishing quality is analyzed. Results carried out show the efficiency of this tool strategy to manufacture parts usually manufactured through a 3-axis milling strategy in SPIF process. Certainly, SPIF applied in NC lathe gain the advantage of a rapid procedure and a low cost.

The purpose of this study is devoted to an “advanced” coupled ductile damage model that describes the elastoplastic behavior of DD13 (Hot rolled steel) sheet material deformed using for the first time a single point incremental forming (SPIF) process. This numerical approach is carried out using a non-associated plasticity model coupled with continuum ductile damage. The constitutive elastoplastic equations and the calculation algorithms are implemented on Abaqus/Explicit via the user interface (VUMAT) subroutine. The numerical simulation is scrutinized two phenomena in this study: the damage behavior and the springback of DD13 sheet material when a conical shape is manufactured using the SPIF process to assess where the damage can accumulate. The simulation results included the damage area of the DD13 sheets, the Hill’48 stress distribution as long as a quadratic function of Hill’48 is used in this formulation, and a comparative figure to explain the final shape of the manufactured part after springback.

This paper deals with an experimental and numerical study focused on the SPIF process of a dome part manufactured by means of a 2-axis NC lathe machine. The main objective is to enhance the understanding of a set of parameters in connection with ISF operations applied to this type of machine unusually used in incremental forming processes, despite the high degree of development of NC lathe machines. Nowadays 4 and 5 axis lathe centers are widely used in industrial applications. This makes NC lathe machines useful in SPIF process especially in the case of axisymmetric parts. The present results, covering thinning, appearance of cracks, surface quality and FLD diagram; prove the efficiency of NC turning machines to perform SPIF application of parts commonly manufactured by a 3-axis NC milling machine.

In this paper, elasto-plastic model based on non-associated flow rule is implemented in Abaqus/Explicit software via VUMAT subroutine to study the influence of some process parameters: cone wall angle, tool diameter, and sheet thickness, on the formability, plastic deformation and thinning during single point incremental forming (SPIF) process. The present work presents useful guidance to show the effect of these three parameters in improving the quality of manufactured products and in obtaining a better formability during SPIF process.

This paper presents material and geometric nonlinear analysis of ceramic/metal functionally graded cylindrical shell using a user-defined subroutine (UMAT) developed and implemented in Abaqus/Standard. The behavior of the ceramic/metal functionally graded cylindrical shell is assumed elastoplastic with isotropic hardening according to Ludwik hardening law. Using the Mori–Tanaka model and self-consistent formulas of Suquet, the effective elastoplastic material properties are determined and are assumed to vary smoothly through the thickness of the cylindrical shell. The effects of the geometrical parameters and the material distribution on nonlinear responses are examined.

The mechanical properties, curing characteristics, and swelling behavior of vulcanized natural rubber (NR) blended with almond shells waste powder (ASWP) with a binary accelerator system are investigated. Results indicate that the mechanical properties were improved. Cross linking density of vulcanized natural rubber was measured by the equilibrium swelling method. As a result, the binary accelerator was found to be able to improve both cure rate and cross-linking density. Using the numerical analysis of test interaction between binary accelerator and operational modeling of vulcanization-factor experiments, it can be concluded that the interaction (Garlic oil, Cystine) was significant and the optimum value of bio-binary accelerator was suggested.

This paper investigates static analysis of multilayered shells with integrated piezoelectric materials. An efficient 4-node shell element is developed to solve piezoelastic response of functionally graded structure with embedded piezoelectric actuators and sensors. A modified First order Shear Deformation Theory (FSDT) is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The properties of subtract material are assumed to be graded through the thickness by the power law distribution while the electric potential is assumed to be a linear function through the thickness of each active sub-layer. Accuracy and convergence of the present model is validated by comparing the numerical results with the published numerical solutions in the literature.

Deep drawing process is commonly used to produce particular components like aerospace and automotive structural parts. Based on the drawing ratio, it can be performed in a single or a multiple-stage drawing. Due the complexity of this process, finite element simulations are considered as a powerful tool for the both reasons: reducing times and costs, and improving quality and productivity. The current study is conducted to evaluate the performance and the capability of a non associated flow rule (NAFR) approach on numerical results during reverse re-drawing process of DDQ mild steel metal. The adopted model is implemented on ABAQUS software using user interface material subroutine (VUMAT).

In this study, numerical analysis of the static bending response of FGM is carried out with different combinaisons of geometries, boundary conditions and mechanical loading. The material properties according to the coordinates of the integration points are defined using the UMAT subroutines in ABAQUS software. The FSDT is used for thin and moderately thick FG shells analysis. The performance of the developed work is illustrated through the solution of several non trivial structure problems from literature. The numerical simulation depicts very close results to solutions in literature which assess the accuracy of the implementation. The proposed solution procedure is significantly efficient from the computational point of view.

This work develops a meshfree method for the analysis of 3D-shell structure based on the modified first order shear deformation theory. The present meshfree method is based on the radial point interpolation method (RPIM) for the construction of the shape functions with Delta function property using arbitrarily distributed nodes in the support domains. The first order shear deformation theory is improved in this work in order to correct the constant shear strains with the Mindlin-Reissner theory and to get closer to its realistic distribution through the thickness with parabolic curves. The accuracy and convergence of the proposed model is compared to results presented in the literature.

This paper focuses on numerical simulation of single point incremental forming (SPIF) process. Via a user-defined material (VUMAT) subroutine is employed to implement a non-associated mixed isotropic–kinematic hardening material model. The accuracy of the proposed non-associated flow rule model to predict the material behavior and the anisotropy in sheet metal forming simulations is examined by comparing numerical results with experimental measurements. The suggested model shows good agreement with experimental results compared to the associated Hill_R and Hill_S models. The proposed non-associated flow rule demonstrates a good efficiency to simulate the springback after sheet metal forming and to predict the thickness variation during incremental sheet metal forming process. The present non-associated model can improve the prediction of both anisotropic and hardening behaviors of material used in numerically controlled sheet metal forming technology.

A geometrically nonlinear analysis of elastoplastic ceramic/metal functionally graded material (FGM) shells is investigated in this paper based on the first-order shear deformation theory. The elastoplastic behavior of the ceramic particle-reinforced metal matrix FGM shell is assumed to follow Ludwik hardening law. The elastoplastic material properties are assumed to vary smoothly through the thickness of the shells. The Mori–Tanaka model and self-consistent formulas of Suquet are employed to locally evaluate effective elastoplastic parameters of the ceramic/metal FGM composite. The homogenization formulation and numerical algorithms are implemented into ABAQUS/Standard via a user material subroutine (UMAT) developed to study the FG shells in large displacements and rotations. With the aim of demonstrating the accuracy of the present method, current numerical results are compared to experimental and numerical ones considering geometrically nonlinear elastoplastic FGMs and show very good agreement. The overall robustness of the new developed solution taking into account both geometric and material nonlinearities is demonstrated through several non-trivial benchmark problems taken from the literature. The effect of the constituent distribution on the deflections is analyzed.

A numerical study was carried out to investigate the low velocity impact behavior of polyamide (PA) as matrix reinforced by a glass fiber. The assessment of the impact behavior requires tensile tests to determine the elastic-viscoplastic behavior of the composites. The numerical results are confirmed by experimental dropping weight impact tests. The material model is implemented in a user-defined material subroutine (UMAT) for the commercial finite element code ABAQUS to predict the numerical response of circular plate of glass fiber-reinforced polyamide subjected to low velocity impact. The effects of glass fiber volume fraction and incidental impact energy on the impact response of the composite circular plates are investigated. The impact analysis of the glass fiber-reinforced polyamide showed that the impactor velocity has considerable effects on the impact response of the composite plates. Also, the contact force changes proportionally with the impactor velocity.

In the present work, an elastoplastic-damage model fully coupled with the constitutive equations of the non-associated plasticity is developed, to enrich the existing research results on the non-associated plasticity finite element models. The yield function and the plastic potential are represented independently by two different (Hill, 1948) quadratic functions to describe the anisotropic behavior of 5083-aluminium alloy. The current model develops a first attempt to establish a general formulation with two ductile degradation functions, one for elasticity and the other for plasticity, with variable degradation coefficients. Further, the elastoplastic behavior of 5083-aluminium alloy is determined through uniaxial tensile tests, so that the anisotropic, the isotropic hardening and the damage parameters are acquired. Experimental-numerical confrontation proves the reliability of the current formulation to describe the behavior of 5083-aluminium alloy with good accuracy. Furthermore, a novel numerical optimization procedure is firstly used to analytically identify Lemaitre damage parameters in order to limit the non-unicity of these parameters. The adopted optimization procedure offers a compromise between good accuracy and low computational time to determine the damage parameters.

The purpose of this paper is to study numerically the “elastomer-assisted compression beading” (EACB process). It consists of conventional compressing beading after a local bulging carried out by an elastomer material. A Finite Element Method (FEM) is introduced to predict where and when the damage can occur in the tube and to study the effects of anisotropy on the occurrence of failure by cracking in regions where damage is accumulated. An anisotropic elasto-plastic constitutive model with mixed non-linear isotropic/kinematic hardening fully coupled with Lemaitre's ductile damage is implemented in ABAQUS/Explicit software via VUMAT subroutine. The influence of anisotropy on the damage evolution is investigated in this study and results are compared with isotropic model.

The incremental sheet forming (ISF) is a flexible forming technology in the sheet metal engineering. This process reaches a higher formability of manufactured sheets than conventional sheet metal stamping process. A deep insight into parameters influencing this process is crucial for more understanding of the process. This paper presents a numerical investigation of damage mechanism during the Single Point Incremental sheet metal Forming (SPIF) of a part with conical shape. An elasto-plastic constitutive model with quadratic yield criteria of Hill’48 and mixed isotropic/kinematic hardening behavior is adopted to simulate ISF operation. A user material subroutine (VUMAT) is employed to implement the material behavior of the sheet metal. The efficiency of the finite element model to predict the material deformation process is investigated by comparing numerical and experimental results. A comparison between two hardening models in terms of deformed shape after springback and thickness evolution is presented. Damage evolution is investigated by comparing the results of two hardening models. The final part is devoted to study the influence of some process parameters on the damage evolution and forming effort during the SPIF of studied parts.

This paper deals with the implementation of an anisotropic plasticity constitutive equations exhibiting non-linear isotropic, kinematic hardening and coupled continuum ductile damage models. A fully implicit integration of the coupling constitutive equations is adopted and leads to two non-linear local scalar equations solved using the Newton method. The consistent local tangent modulus is obtained in a closed form by exact linearization of the algorithm. The numerical treatment of the proposed algorithm is implemented on ABAQUS using user interface material subroutines (UMAT and VUMAT). The performance of the present algorithm is assessed and bared out by numerical examples.

A finite element simulation of flexible bulge forming of aluminum sheet metal is carried out. The effect of rubber pad on forming capability is studied by comparing flexible bulge to hydroforming. Based on the theory of Continuum Damage Mechanics (CDM), a local approach with fully coupling between ductile damage and an anisotropic elasto-plastic model with mixed nonlinear kinematic/isotropic hardening is introduced. The model is implemented into a user-defined material (VUMAT) subroutine for the commercial finite element code ABAQUS/Explicit. A Mooney-Rivlin theory is adopted for rubber material behavior. Comparisons between both processes in terms of thickness variation, damage occurrence, and sheet formability are conducted for different rubber shores and friction. Numerical findings are in a good correlation with experiments from literature.

A numerical investigation was carried out to analyze in details the perforation process of target AA5754-O Aluminum plate when subjected to normal impact at low (up to 25 ms − 1 ) and moderate velocities (ranged between 25 − 50 ms − 1 ). A fully coupled elasto-visco-plastic-damage model is implemented into a user-defined material (VUMAT) subroutine for the commercial finite element code ABAQUS/Explicit. The strain rate effect is considered. Comparison between isotropic J 2 and orthotropic Hill yield criteria associated with isotropic and mixed non-linear isotropic/kinematic hardening was conducted. A parametric study of the effect of anisotropy, plate thickness and impactor nose shapes on ballistic limit and petal forming is carried out. A good agreement is found between numerical and experimental results conducted by other researchers.

A meshless implementation of arbitrary 3D-model based on a double directors shell element is developed in this work. The meshless technique is based on radial point interpolation method (RPIM) used for the construction of the shape functions for arbitrarily distributed nodes of the shell geometry. The high order shear deformation theory is adopted in this work in order to remove the shear correction coefficient. The convergence of the proposed model is compared to other well-known formulations found in the literature in order to outline the accuracy and performance of the present model.

This paper is concerned with a piezoelectric shell element to analyze smart structures. The finite element formulation is based on discrete double directors shell elements. The implementation is applicable to the analysis of laminated shells with integrated piezoelectric layers. The third-order shear deformation theory is used in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The element has four nodes with eight nodal degrees of freedoms: three displacements, four rotations and one electric potential, which is assumed to be a linear function through the thickness of each active sub-layer. The piezoelastic behavior of smart composite plate is examined. The obtained results are compared to existing solutions available in literature. An excellent agreement among the results confirms the high accuracy of the current piezoelastic model.

This paper presents a numerical simulation of single point incremental forming (SPIF) process. An elasto-plastic constitutive model with quadratic yield criterion of Hill’48 based on a combination of the non-associated flow rule theory and mixed isotropic-nonlinear kinematic hardening behavior has been implemented in user material subroutine (VUMAT) to describe the behavior of sheet metal during SPIF process. The simulation results included the variation of the thickness along transverse direction and the localization of the major Von Mises stress.