Plastic Deformation Of Plates Research Articles

A.A. ILYUSHIN'S FINAL RELATION, ALTERNATIVE EQUIVALENT RELATIONS AND VERSIONS OF ITS APPROXIMATION IN PROBLEMS OF ELASTIC DEFORMATION OF PLATES AND SHELLS. PART 2: ALTERNATIVE EQUIVALENT RELATIONS OF A.A. ILYUSHIN

The finiterelationship between the forces and moments of plates and shells in the parametric form of the theory of small elastoplastic deformations is investigated of A.A. Ilyushin, to determine the load-bearing capacity of structures from a material without hardening. A geometric image of the exact yield surface in the space of generalized stresses is obtained. In the firstpart of the article the conclusion of the finalrelation is given. In the second and third parts, by introducing other parameters, alternative equivalent dependences of the finalrelationship have been developed and variants of its approximation for application in computational practice are considered. In the fourth part, additional properties of the finalrelationship are considered, the possibility and necessity of its use in problems of plastic deformation of plates and shells is shown.

A.A. ILYUSHIN S FINAL RELATION, ALTERNATIVE EQUIVALENT RELATIONS AND VERSIONS OF ITS APPROXIMATION IN PROBLEMS OF PLASTIC DEFORMATION OF PLATES AND SHELLS PART 1: A.A. ILYUSHIN S FINAL RELATION

The finite relationship between the forces and moments of plates and shells in the parametric form of the theory of small elastoplastic deformations is investigated of A.A. Ilyushin, to determine the load-bearing ca­pacity of structures from a material without hardening. A geometric image of the exact yield surface in the space of generalized stresses is obtained. In the first part of the article the conclusion of the final relation is given. In the second and third parts, by introducing other parameters, alternative equivalent dependences of the final rela­tionship have been developed and variants of its approximation for application in computational practice are considered. In the fourth part, additional properties of the final relationship are considered, the possibility and necessity of its use in problems of plastic deformation of plates and shells is shown.

Design method for steel deck plates under quasi-static patch loads with allowable plastic deformations

Plastic deformation of plates in steel deck structures under heavy vehicle or helicopter wheel loads is common in ships and offshore structures, and is therefore of significant interest to designers of ro-ro/cargo ships, helicopter-carrying ships and offshore platforms. To provide insight into the plastic deformation of plates, the nonlinear elasto-plastic response of stiffened steel plates loaded quasi-statically by a central rigid rectangular indenter is investigated both experimentally and numerically. The numerically-determined stiffened plate permanent deflections compare well with those obtained experimentally. The concept of applying the elasto-plastic method to the design of deck plates under wheel patch loads is introduced, and the design principle of wheel patch loaded plating is studied together with the design criteria. A simple design formula to determine plating thickness is proposed based on an acceptable level of permanent set. Ship-mounted helideck plating design cases are given to illustrate the elasto-plastic method, and comparisons are made between the thicknesses derived using the proposed design formula and those found from Lloyd's Register (LR), Bureau Veritas (BV) and DNV-GL rule requirements.

Viscoelastic—Plastic Deformation of Plates with Spatial Reinforcement Structures

A mathematical model of viscoelastic-plastic bending deformation of spatially reinforced plates is developed based on the time step method. The viscoelastic behavior of the components of the composition is described by the Maxwell-Boltzmann equations, and plastic behavior by flow theory with isotropic hardening. The low resistance of composite plates to transverse shear is taken into account within the framework of Reddy’s theory, and the geometric nonlinearity of the problem is considered in the von Karman approximation. The corresponding initial-boundary-value problem is solved using a leapfrog numerical scheme. The dynamic viscoelastic-plastic bending of spatially reinforced fiberglass rectangular plates subjected to air blast wave loading is investigated. It is shown that for relatively thick plates, replacing a flat reinforcement structure by a spatial reinforcement structure leads to a significant decrease in the maximum and residual deflections and strain intensity of the binder material, and for relatively thin plates, this replacement is ineffective. It is found that in the initial stage of deformation, the amplitude of oscillation of the composite plate far exceeds the residual deflection.

Numerical Study of Asymmetric Friction Connections (AFC) with Large Grip Length Bolts

A Finite Element (FE) model is used to simulate the experimental behaviour of high strength bolts in asymmetric friction connections (AFC). Two M16 connections tested previously are modelled using ABAQUS and are subjected to cyclic lateral displacements. The numerical results were similar to that from previous experimental studies. It was also shown that hysteresis loop strength and stability reduced for longer bolt grip lengths. Other information, which cannot be easily monitored in experimental tests, such as the bearing stress distribution between plates, component equivalent plastic strain, and bolt tension force, were obtained at different sliding distances. It was shown that bolt and plate plastic deformation tended to occur in bolts with a long grip length to bolt diameter ratio.

The influence of circuit inductance on the energy characteristics of electric discharge and deformation of plates in water

We have experimentally studied the influence of discharge-circuit inductance on the efficiency of conversion of energy stored in a capacitor bank, evolved in the electric-discharge channel in water, and spent for the resulting plastic deformation of plates. It is established for the first time that a growth in inductance of the discharge circuit produces a positive effect on the deformation of plates by increasing the amount of energy spent in this process.

A Study Effect of Shooting 2 Balls in a Ball Swaging Process on Gram Load Parameter Using Finite Element Analysis

The purposes of this research are to explore the baseplate and actuator arm deformation which effect to the gram load which occur in the ball swaging process, the main component determining quality of assembly the head stack assembly with the actuator arm. By shooting a ball though the base plate, the component located on the head stack assembly, the base plate plastic deformation takes place and it in expand in radial direction. The base plate then adjoins with the actuator arm. Using the finite element method to reproduce the ball swaging process, we repeated to study effect of the swage press clamp and velocity. The study done by creating the three dimensionals finite element model to analyze and explain characteristics of the baseplate and actuator arm deformation which effect to gram load which effect to the ball swaging process.

Adaptive Finite-element Analysis of Plastic Deformation of Plates under Projectile Impact

This paper deals with the finite-element analysis of plastic deformation of plates during normal impact of projectile on plates, The finite element method implemented here is based on the flow formulation of plasticity. During projectile impact the geometrical configuration of domain is progressively altered that generally causes distortion of mesh. It affects the accuracy of finite-element solution, Hence, a posteriori error estimation for the computed finite-element solution has been incorporated to capture the zones of high stress and strain gradients. The h-refinement of the mesh is carried out over such domain to limit the solution error, Two projectile impact problems on a circular aluminium plate-one by a blunt-end projectile and another by a hemi-spherical-headed projectile-are analysed to illustrate the proposed method.

Effects of Void Growth and Nucleation on Plastic Deformation of Plates With Fluid-Structure Interaction

A plate-bending formulation was developed from a three-dimensional solid. The plate element includes both transverse shear and normal deformations and the transverse gradient load (TGL) which is associated with the transverse normal deformation. The element utilizes reduced integration along the in-plane axes and full integration along the transverse axis. The formulation incorporates Gurson’s constitutive model for void growth and plastic deformation. An algorithm for stable solutions of the nonlinear constitutive equations is also discussed. Hourglass mode control is provided by adding a small fraction of internal force determined through full integration along the in-plane axes and reduced integration along the transverse axis. Numerical examples are presented for plastic deformation of a plate with fluid-structure interaction to examine the effects of void growth and nucleation in plastic deformation.

Optimization of Dynamic Plastic Deformation of Plates with a Complex Contour

A method for studying dynamic deformation of ideal rigid–plastic plates with a complex contour on a viscoelastic foundation is proposed. The method allows one to optimize the process of pulsed forming. The optimization parameters are the amplitude of the pulsed load, viscoelastic damping coefficients of the foundation, the surface density of the plate material, and the shape and supporting conditions of the edges. Numerical examples of simply– and doubly–connected plates are given. It is shown that different combinations of the control parameters of the process can ensure the same final shape of the plate formed.

A geometrically consistent plate-tectonic model for eastern Indonesia

This paper is the result of an exercise to find out to what extent the various large-scale geometrical characteristics and geodynamic data of eastern Indonesia are putting boundary conditions on the late Cenozoic plate tectonic evolution of the area. The model presented here consists of six rigid plates, which rotate around moving Euler poles under mechanically-geometrically controlled conditions and is geometrically consistent for the past 10 Ma. The changing plate tectonic pattern in the model gives an indication of the possible tectonic events in the history of various localities. It appears possible to explain the origin of the major geological features of eastern Indonesia simultaneously and within the framework of relative motions of the Eurasian, Pacific and Australian Plates. The model shows that, in reconstructing the geodynamic evolution of eastern Indonesia, features like extensive seafloor spreading, plastic deformation of plates, or spasmodic plate motions are not required.

Estimation of Structural Service Life of Ships

ABSTRACTA methodology for the structural life assessment of a ship's structure is suggested. The methodology is based on probabilistic analysis using reliability concepts and the statistics of extremes. In this approach, the estimation of structural life expectancy is based on selected failure modes. All possible failure modes of the ship must be investigated and the most likely paths to structural failure identified. For the purpose of illustration two failure modes are considered in this study. They are plate plastic deformation and fatigue cracking. Structural life based on these two failure modes is determined for an example vessel.The methodology determines the probability of failure of the ship's structural components according to the identified failure modes as a function of time. The results can be interpreted as the cumulative probability distribution function (CDF) of structural life. Due to the unknown level of statistical correlation between failure modes, limits or bounds on the CDF of the structural life are established. The limits correspond to the extreme cases of fully correlated and independent failure modes. The CDFs of structural life are determined for two inspection strategies; namely, inspection every year and inspection every two years with a warranty inspection at the end of the first year.The meaning of the results for the case investigated in this study is that, for example, given an inspection strategy of two years and a desired life of 15 years, there is a 72% chance that the vessel will not experience enough partial damage‘ in the failure modes identified to constitute reaching the “end of structural life” as defined.

Solution of two-dimensional problems of plastic deformation of plates and membrane shells

Solution of two-dimensional problems of plastic deformation of plates and membrane shells

Impact Strength of Materials

This book presents a compilation of information and analytical methods on the subject of the impact strength of materials. It contains ten chapters dealing with: 1, elementary one-dimensional elastic stress waves in long uniform bars due to impact; 2, applications of elementary one-dimensional stress wave theory; 3, elastic stress waves: more general considerations; 4, plasticity theory and some quasi-static analyses; 5, one dimensional elastic-plastic stress waves in bars; 6, impulsive loading of beams; 7, dynamic loading of rings and frames; 8, dynamic plastic deformation of plates; 9, plastic deformation in a semi-infinite medium due to impact; and 10, plastic deformation in plates due to impact. Two appendices contain: 1, useful conversion factors; and 2, text tables in SI units. (TRRL)

Reinforced openings in plastically deforming plates: A finite-difference analysis

This investigation deals with the stress and strain distribution in a large plate containing a reinforced circular hole when loaded monotonically in uniaxial tension beyond the elastic range. The hole is reinforced with a cylindrical member which is symmetrical with respect to the plate to which it is continuously joined. Consideration is given to various degrees of plastic deformation of plate and reinforcement corresponding to various uniaxial tension loads. Whole-field analyses of the reinforcement in cylindrical co-ordinates and of the plate in plane polar co-ordinates are obtained by the finite-difference method in which the governing equilibrium equations are expressed in terms of displacements and plastic strains. Deformation theory of plasticity is employed. Limitations of the ‘compact’ reinforcement assumption result from the subsequent whole-field investigation.Results are obtained for material of a specific stress-strain curve so that strain-gauge results could be compared with the strains predicted by the finite-difference analysis. It is demonstrated that the compact reinforcement is adequate for analysis of the plate, but for a very significant range of reinforcement geometry it neglects a more serious stress concentration in the reinforcement. For the whole-field analysis, prediction of first yield is made for four critical points: tensile-stress concentration in the plate; tensile-stress concentration in the reinforcement; and shear-stress concentrations in both plate and reinforcement at their joint.