Elastic-plastic Analysis Research Articles

Analysis and Computer Dynamic Three-Dimensional Model of Seismic Measures for High Rise Steel Frame Structure Using Finite Element Software

The newly-built 20-story hospital building is located in the seismic fortification 8 degree area, and its independent steel corridor is a steel frame structure. In order to analyze the performance of the structure under strong earthquake, the static and dynamic elastoplastic three-dimensional finite element model of the structure is established by using the finite element software PERFORM-3D. In this paper, buckling restrained braces are used for energy dissipation. Through the dynamic elastic-plastic analysis of the steel frame buckling restrained brace structure, the structural response under strong earthquake input is analyzed, and the structural reliability is checked.

Control and research of lead shear damper in a typical energy dissipation high-rise structures

To study the lead dampers damping effect in the High-Rise frame-shear wall structures, a High-Rise structure is adopted as engineering background. Firstly, the dynamic performance of the structure is analyzed by SAP2000. Secondly, the energy dissipation suspension design is done in this paper. Finally, the nonlinear finite element analysis software ABAQUS is used to analyze the seismic performance of a High-Rise frame-shear wall structure with lead shear dampers under the action of the rare earthquake and compare the elastic-plastic analysis results under the action of different seismic wave. Analysis results show that the structural seismic performance has been improved significantly, A successful engineering case was provided for the application of lead shear dampers in the damping design of high-rise frame-shear wall structures.

The dynamic elastic-plastic analysis of frame- shear wall structure of a power plant main building

The main machine hall has the characteristics of the uneven distribution of mass and stiffness. It is important to research the structural seismic performance to ensure the normal operation of power plant, prevent serious damage to important equipment and personnel. This paper uses the general finite element software ABAQUS to investigate seismic performance of structures under strong earthquakes, the various parts of the inelastic phase sequence, damage degree and distribution, and on this basis puts forward opinions and suggestions on structure scheme. The analysis results show that the structural maximum interlayer displacement Angle can meet the demands of 1/100 limit, the seismic fortification standard of “no collapse under strong earthquake” can be achieved and the results can provide important basis for design.

Study on swage autofrettage of steel sleeve for the high pressure plunger pump

Based on bilinear hardening material model, the swage autofrettage technology of steel sleeve for pump is analyzed. The theoretical calculation formulas of stress, strain, residual stress and strain and punch thrust of swage autofrettage steel sleeve are derived by the elastic-plastic analysis. The accuracy of the theoretical formulas is verified by the swage autofrettage experiment. The result of theoretical calculation is consistent with that of the experiment, and the process of the second loading does not affect the autofrettage result. The theoretical calculation formulas can be used to guide the swage autofrettage technology design of the steel sleeve for the pump.

Seismic Performance Analysis of Reinforced Concrete Frame Structures Based on Computational Mechanics

In order to study the degradation law and seismic performance of reinforced concrete frame structure with the extension of service time under normal service environment, the multi-scale modeling of corroded reinforced concrete frame is carried out by using the general finite element analysis software ABAQUS. The correctness of the multi-scale modeling method is verified by the experimental data of corroded reinforced concrete members and single frame. The pushover analysis and elastic-plastic time history analysis of a four story reinforced concrete frame structure are carried out by using a multi-scale model. Then the seismic response and damage of RC frame structures with different service time are compared. The experimental results show that the established seismic performance model of reinforced concrete frame structure is more practical in practical application and can meet the research requirements.

판구조물의 절단에서 발생하는 잔류변형을 적용한 용접해석

Cutting and welding are essential processes in constructing complex steel structures. In these processes, local heating and cooling generate strains and stresses in the cut and welded areas, resulting in deformation of the entire structure. To accurately predict the welding deformation of the model, it is necessary to consider the effects of previous cutting. In this study, thermal conduction analysis was used to derive the temperature history via cutting and bead-on-plate welding. Additionally, temperature history was applied to thermal–elastic–plastic analysis of welds while cutting. When applied to large structures, a simplified analysis was performed. Thus, the thermal–elastic–plastic analysis results were applied in a shell structure as equivalent shrinkage and moment, and elastic analysis was performed. Through this study, it was confirmed that cutting influenced the final welding deformation. Further, the suitability of the simplified method for analyses of large structures was verified.

Critical Review of ASME III Plasticity Correction Factors for Fatigue Design-By-Analysis of Nuclear Power Plant Components

Abstract Despite significant technological progress in recent years, elastic–plastic fatigue analysis of pressure-retaining components remains a time-consuming venture. Accordingly, nuclear pressure vessel design codes such as ASME Section III provide simplified elastic–plastic analysis procedures as a practical alternative. This approach can be excessively conservative under certain conditions due to the bounding nature of the applied plasticity correction factor, Ke. While this over conservatism was tolerable in the past, recent technical challenges arising due to consideration of environmentally assisted fatigue and design for long-term operation have posed difficulty in achieving acceptable fatigue usage based on extant Code assessment procedures for certain components. The incorporation of more accurate Ke factors has since been identified as a nuclear industry priority. This paper presents a critical review of Ke factors within ASME Section III, with particular attention given to an approach proposed by Ranganath, which has recently been approved for publication as an ASME Section III Code Case. Correction factors adopted within other nuclear and nonnuclear codes and standards (C&S) were also considered. The code-based Ke factors were compared with Ke factors obtained directly from various elastic–plastic finite element (FE) models of representative plant components. The results revealed a considerable difference in conservatism between the code-based methods. Based on the elastic–plastic finite element analysis (FEA) results, an alternative improved plasticity correction method is proposed in this paper. The need for a harmonized approach to determining Ke based on elastic–plastic FE analysis and further development of efficient plasticity correction methods for total life assessment are highlighted as desirable industry objectives.

Theoretical and numerical fracture analysis of bovine cortical bone under tensile loading in mode I and mixed-mode fracture

Elastic and elastic–plastic theoretical and numerical analyses are performed to evaluate the bone containing initial crack. The mode I + II of fracture is applied to identify the most critical incline crack and the analytical results are compared with experimental evaluation. The loading capacity in bones with smaller thickness decreases more significantly in the elastic–plastic analysis. Both plastic zone and the elastic–plastic stress are higher in smaller initial crack length. Simultaneous initiation of non-close multiple cracks has no significant influence on the ultimate tensile load and the effect of crack width on fracture decreases in higher crack width and longer length.

Round robin analysis to investigate sensitivity of analysis results to finite element elastic-plastic analysis variables for nuclear safety class 1 components under severe seismic load

As a part of round robin analysis to develop a finite element elastic-plastic seismic analysis procedure for nuclear safety class 1 components, a series of parametric analyses was carried out on the simulated pressurizer surge line system model to investigate sensitivity of the analysis results to finite element analysis variables. The analysis on the surge line system model considered dynamic effect due to the seismic load corresponding to PGA 0.6 g and elastic-plastic material behavior based on the Chaboche combined hardening model. From the parametric analysis results, it was found that strains such as accumulated equivalent plastic strain and equivalent plastic strain are more sensitive to the analysis variables than von Mises effect stress. The parametric analysis results also identified that finite element density and ovalization option in the elbow elements have more significant effect on the analysis results than the other variables.

Structural integrity assessment of plates containing embedded cracks-part I: Finite element fracture analyses

In this two-part paper, guidance for assessing plates containing embedded elliptical cracks under complex loading conditions is developed, based on the fracture mechanics validation of the limit load solutions using the finite element (FE) J solutions. In Part I of this paper, elastic-plastic 3D FE analyses are performed for plates with embedded off-set elliptical cracks under combined biaxial stresses and through-thickness bending for developing a FE J database containing 612 cases. Totally 18 cracked plate models are created. For each cracked plate, 17 load combinations are considered and two material strain hardening exponents are analysed. The obtained plastic J solutions are correlated as the EPRI type fully-plastic J factor h1. The effect of the applied normal stress parallel to the crack plane, σ2, on the elastic-plastic J behaviour is investigated and it is found that the EPRI linear addition J estimation scheme may not describe the elastic-plastic J behaviour very well for cases under combined bending moment and σ2. The limit load validation using the FE J solutions is detailed in Part II of this paper.

Analysis of energy consumption of a main machine hall for a thermal power plant with lead dampers

The lead damper is a kind of energy dissipating device with stable hysteretic performance, good shock absorption performance and simple structure. To study the lead damper damping effect in the main machine hall, the nonlinear finite element analysis software ABAQUS is adopted to analyze the seismic performance of a main machine hall with lead damper under the action of the rare earthquake and compare the elastic-plastic analysis results under the action of different seismic wave in this paper. The results show the structural seismic performance has been improved significantly, “no collapse under strong earthquake” can be achieved, A successful engineering case was provided for the application of lead damper in the damping design of main machine hall structures.

Elastic-plastic analysis of reinforced concrete frame buildings: Developing a new software package

In this work we will explain a new methodology that have been utilized in a new software package (program) to determine the lateral loads at which a 3D reinforced concrete frame building collapses. The solution is represented by forming the capacity curve (force–displacement) of the structure taking into account the elastic-plastic behavior of the element materials represented by plastic hinges positioned at the ends of the linear elements. This work takes into account only the plastic hinges caused by bending moments. The program is based on finite elements method and capable of analyzing and designing three dimensions buildings. The program provides a drawing environment (3D view, plan view, elevation view) with tools to create the model and to perform the structural analysis and design.

A Methodology to Determine the Effective Plastic Zone Size Around Blunt V-Notches under Mixed Mode I/II Loading and Plane-Stress Conditions

The determination of the ductile failure behavior in engineering components weakened by cracks and notches is greatly dependent on the estimation of the plastic zone size (PZS) and, particularly, the effective plastic zone size (EPZS). Usually, time-consuming complex elastic–plastic analyses are required for the determination of the EPZS. Such demanding procedures can be avoided by employing analytical methods and by taking advantage of linear elastic analyses. In this sense, this work proposed a methodology for determining the PZS around the tip of blunt V-notches subjected to mixed mode I/II loading and plane-stress conditions. With this aim, firstly, existing approximate mathematical expressions for the elastic stress field near round-tip V-notches reported in the literature are presented. Next, Irwin’s approach (fundamentally proposed for sharp cracks) and a yield criterion (von Mises or Tresca) were applied and are presented. With the aim of verifying the proposed methodology, elastic–plastic finite element analyses were performed on virtual AISI 304 steel V-notched specimens. It was shown that the analytical formulations presented cannot estimate the complete shape of the plastic zone. However, the EPZS, which is crucial for predicting the type of ductile failure in notched members, can be successfully estimated.

Influence of spatial welding on the accuracy of working dimensions of drilling chisels of cutting-erasing type

The article considers the problem of PDC drill bit quality provided during manufacturing. Schemes of welded joint making are theoretically substantiated based on theoretical research, computer modelling and experimental tests for L-shaped details like PDC drill bit blades. The recommendations to provide welded joints for L-shaped details are developed. Based on the elastic-plastic analysis, means to reduce thermal longitudinal and transverse internal deformations caused by a heat source moving along the weld are theoretically substantiated. Simulation models have been developed to assess the influence of welding thermal action and residual deformations on accuracy of drill bit external diameter for different schemes of welding. Based on the developed models, it is shown that the thermal welding deformations of spatial curved welds are significant, and relate mainly to the blades rather than the body (i.e. less massive parts); there are bends, turns and skews of the blades. Finite-element simulation of the bit body – welded blades stress-strain state was performed sequentially in the environment ANSYS (academic license) – Transient Thermal (determination of heat load) and Static Structural (determination of deformations and stresses). It is established that the smallest deformations of the blade are observed for the welding scheme, which envisages making the weld from the point of cylindrical and ellipse surface pairing. The results obtained by simulations were confirmed by experimental data and this made possible substitution for a rational scheme of drill bit body – blade based on the method of reverse deformation, to ensure the accuracy of the product as a whole. Recommendations for weld joint making for spatial curved welds of complex products with requirements to their accuracy allow increasing the accuracy of the technology by minimizing the thermal load and residual thermal deformation of the joints.

Analytical Investigation on Elastic–Plastic Deformation of Reentrant Honeycomb Structures

Analytical elastic–plastic analysis is presented to investigate the in-plane deformation of the reentrant honeycomb structures subjected to tension or compression. An analytical elastic–plastic deformation analysis is carried out and the nonlinear stress–strain relation of honeycombs is presented, reflecting the dependence of equivalent stress, equivalent Young’s modulus, and equivalent Poisson’s ratio on the deformation. The modified factors of the stress–strain relation are then presented, which depend on the shape and deformation of the honeycomb structure and are independent of the material Young’s modulus and the ratio of wall thickness to its length. It is found that, by adjusting the geometric or material parameters, we can enable this reentrant honeycomb structure to achieve a range of negative Poisson’s ratio and Young’s modulus values. A finite element model is used to indicate the effectiveness of the proposed model. A parametric study is finally carried out to investigate the effects of the geometric or material parameters on the reentrant honeycombs structure.

An efficient simplified elastic–plastic analysis procedure using engineering formulae for strain-based fatigue assessment of nuclear safety class 1 piping system subjected to severe seismic loads

This paper proposes an efficient simplified elastic–plastic analysis procedure using engineering formulas to perform strain-based fatigue design considering the plasticity that occurs in nuclear safety class 1 piping systems during severe seismic loads, and then presents the application results of the procedure to a pressurizer surge line system. The total strain amplitudes, fatigue assessment results, and total calculation time were compared between the proposed procedure and the detailed dynamic finite element elastic-plastic analysis. The comparison confirmed that the proposed analysis procedure can efficiently derive reasonable and conservative results for nuclear safety class 1 piping systems under severe seismic loads.

Seismic isolation design of structure using variable friction pendulum bearings

Herein, analytical and experimental investigations are conducted to characterize the performance of a novel variable friction pendulum bearing (VFPB) capable of progressively exhibiting different hysteretic properties for different displacement amplitudes. An analytic scheme comprising existing nonlinear elements is proposed, which can be easily implemented using currently available analysis software. The analytic-scheme accuracy is verified through comparison with experimental data. Thereafter, a design method is developed for seismically isolated buildings employing VFPB. Elastic-plastic time-history analyses are performed to study the seismic performance of the base-isolated building using VFPB, by comparing its performance with that of a friction pendulum bearing (FPB). Both the buildings isolated employing VFPB and FPB exhibit excellent aseismic performance. The VFPB is more effective than FPB in reducing the response of superstructure without increasing isolator displacement for the rare earthquake scenario, especially for very rare earthquake scenario. The stiffness and damping of VFPB change to predictable values at calculable and controllable displacement. Therefore, it can be designed to achieve multiple performance objectives corresponding to different levels of ground shaking.

Multi-Pass Welding Distortion Analysis Using Layered Shell Elements Based on Inherent Strain

In this article, a layered shell element-based, elastic finite element method for predicting welding distortion in multi-pass welding is developed. The welding distortion generated in each pass can be predicted by employing layer-by-layer equivalent plastic strains as thermal expansion coefficients and using the heat-affected zone (HAZ) width as the mesh size. The final distortion can be expressed as the sum of the distortions for each pass. This study focuses on extraction of the equivalent plastic strain and HAZ width through 3D thermal elastic plastic analysis (TEPA) for each pass. The input variables extracted from each pass can be converted and added to simulate the final distortion of the multi-pass welding. A 10 mm thick, multi-pass butt-welded joint, subjected to three passes, is simulated via the proposed method. The predicted welding distortion is compared with the 3D TEPA results and the measured experimental data. The outcome indicates that good agreement can be obtained.

Local Elasto–plastic Buckling of Isotropic Plates With Cutouts Under Tension Loading Conditions

The motivation of the presented study was the observation of the existence of local loss of stability “tension buckling” in the experimental tests of composite and metallic plates with cut-outs subjected to tension. Because of this, the numerical analyses of the aluminum plate with elliptical or circular cutouts at the center and subjected to tensile load are studied in the paper. Although the whole structure is uniformly stretched, the circumferential compressive stresses in the vicinity of the cutout edge are observed. First of all, the linear buckling analysis is carried out for different sizes of the holes. Based on these results, the size of the hole is chosen, where the circumferential stress magnitude in the vicinity of the cutout is the lowest or even comparable to the yield stress of the material. The computations are made for three different values of thickness. Finally, the nonlinear buckling analysis is carried out without and with the plasticity effects included. Generally, in the case of the circular and vertically oriented elliptical cut-out, the loss of stability in the tensed plate is always observed. However, in elastic-plastic analyses, the values of the critical parameters significantly differ from the results obtained for elastic buckling. Finally, the critical geometries for further experimental tests were defined.

Elastic-plastic buckling analysis of stiffened panel subjected to global bending in forming process

A new method has been proposed in this study for the elastic-plastic buckling analysis of stiffened panels under global bending. In this method, a simplified model of the stiffened panels has been built with the application of two theories of plasticity, the incremental theory (IT) and the deformation theory (DT). The effect of transverse shear deformation through the stiffener thickness has been considered using the Mindlin-Reissner plate theory. The governing differential equations have been solved by the differential quadrature (DQ) method and an iteration process has been adopted due to the non-linearity of material properties in the elastic-plastic buckling analysis. Non-linear finite element (FE) modelling of elastic-plastic buckling analysis has been carried out, and the FE results are between those based on DT and IT in general. When the reciprocal of strain hardening exponent mt increases to 20, the FE results are in a good agreement with DT results. Based on the proposed method and FE simulations, the effect of geometric parameters of stiffened panels (stiffener thickness to height ratio, stiffened panel length to height ratio, width to height ratio, and skin thickness to stiffener thickness ratio) on buckling behaviour in the elastic-plastic region has been investigated and discussed. The proposed method provides an efficient way for parameter optimisation in the structure design of stiffened panels for the aerospace applications.