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This paper presents the laboratory result on compaction characteristic for soft soil subgrade which was stabilized by using waste paper sludge ash (WPSA). The soft soil sample was collected from Banting Selangor, Malaysia named as Banting soft soil and classified as slightly sandy Clay with intermediate plasticity. Additive of WPSA is a finely waste product produced from the incinerated waste paper. In ASTM C618, this WPSA samples are categorized as Type-C fly ash due to the high free lime (CaO) content (>20%) and possesses some cementitious and pozzolanic, resulting in the self-cementing characteristics. Therefore no entire activators such as lime are required. Objectives of this study are to determine the dry density and moisture content of Banting soft soil stabilized by WPSA through the different energy and method of compaction and to determine the Atterberg limit properties of Banting soft soil stabilized using WPSA. Several percentage of WPSA (4%, 8%, 12% and 16%) was used to stabilize the soft soil. Meanwhile the compactions methods are used in this study are standard proctor test and modified proctor test. The Atterberg limit properties testing involved the liquid limit testing, and plastic limit testing. The result showed the plasticity indexes of soft soil stabilized with series percentage (4%, 8%, 12% and 16%) of WPSA were reduced parallel to the increment of liquid limit and plastic limit result. Meanwhile, the compaction result for stabilized soft soil showed an increment dry density value followed by decrement of moisture content for modified compaction and standard compaction. However, 4% WPSA were giving the best of optimum moisture content and maximum dry density stabilized soft soil from modified compaction. From this experimental study, it shows that WPSA has a significant and effective to improve the geotechnical properties of soft soil. [ABSTRACT FROM AUTHOR]

An automated sensor has been developed for use during paper manufacture that can measure flexural rigidity (bending stiffness). Based on laser ultrasonic technology, this sensor provides continuous noncontact on-machine measurements on paper having area densities from 35 to 205 g/m2, moving at commercial manufacturing speeds, at any angle in the plane of the sheet. It was demonstrated on a high speed printing paper grade machine during commercial production. For that demonstration, the sensor was integrated into an existing scanning sensor system. Cross-direction profiles of flexural rigidity had the expected shape, and compared well with traditional bending stiffness measurements on samples collected for that comparison. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The paper discusses the possibility of increasing the plasticity coefficient of buildings and link by including in friction-movable joints on high-strength bolts in construction links. Such link connection is modeled by a dry friction damper or a dry friction damper with a decreasing friction force. The use of such joints makes it possible to increase significantly the area of static uncertainty loss in the monotonous loading diagram of the structure and, accordingly, the work of plastic deformation forces needed for the structure destruction. The paper considers two examples of using friction-movable joints. The first example is related to designing an onshore flyover sea platform. To provide the seismic platform stability proposed the authors to cut the platform longitudinally into onshore and offshore parts, which are connected by means of friction-movable joints. The second example relates to the seismic protection of railway bridges, in which the superstructure, in the place of location of fixed bearings, is connected to the bridge pier using a friction-movable joint. In this paper, the proposed connections are designed for the actions of design and maximum design earthquakes. Scenarios of damage accumulation in the structures under consideration during earthquakes are presented. [ABSTRACT FROM AUTHOR]

The paper considers the development that relates to machine-tool industry, in particular, to technological processes of cutting and surface plastic deformation of low-rigid parts with automatic control of a self-centering steady rest. The installation helps to control automatically the position of the shaft-type work piece axis and eliminate self-oscillations that occur when turning low-rigid ax symmetric parts. The paper states a new issue in the turning process. The position of the work piece axis is stabilized in the cutting zone in the ZOY plane, which makes it possible to increase the machining accuracy and cutting conditions. The controlled self-centering steady rest helps to process stepped parts with surface-plastic processing. The axial force is recorded applying a sensor installed on the steady rest lever, and is corrected using information about the opposite cutting zone. The installation is mounted on the machine support from the opposite cutting zone and is equipped with a four-circuit control system with a hydraulic steady feed drive. [ABSTRACT FROM AUTHOR]

The present paper analyzes failure observed in polymer rods collided with a steel anvil under the Taylor cylinder impact experiments. The experimental and numerical analysis demonstrates that association of the failure patterns with the loading mode depends on the rod material. Two materials are considered in the paper, specifically, polymethylmethacrylate (PMMA) and polycarbonate (PC). Damage in PMMA rods at the Taylor tests is shown to be dominated by the shear load resulting in plastic deformation. In contrast, the major mechanism of damage in PC rods is governed by omni-directional (pressure) mode of load. Analysis of the damage in sections of the rods associated with the glass transition is also addressed in the present theoretical study. Failure in these polymers follows the traditional fracture wave mechanism for brittle glass-type materials due to load in the corresponding mode. Numerical analysis employs a two-phase model with improved inter-phase thermal balance accounting for the inter-phase mass, momentum, and heat exchanges during the glass phase transition, while damage being accumulated in time. The simulation results demonstrate a good correlation with the experimental results. [ABSTRACT FROM AUTHOR]

This paper reports a numerical study of low-velocity impact heat generation in a confined HMX-based polymer bounded energetic material. For a long time, two mechanisms were suspected to heat the microstructure and then to yield an ignition: the plastic deformation of HMX crystals or the friction between the lips of microcracks or between crystals. This paper is devoted to the first mechanism. The aim is to determine if plasticity can significantly increase the local temperature during low-velocity impacts. The calculations are based on a HMX crystal plasticity (parameters from the literature) and strong assumptions, at the polycrystal level, based on experimental evidences. Shearing polycrystals yields the relation between the macroscopic and the microscopic mechanical dissipations. Then, this relation and the heat released by the chemical decomposition of the energetic material are used to determine ignition during target/projectile simulations. The good accordance between measurements and simulations for low-velocity impacts was obtained without using impact tests for the calibration of the parameters. This study shows that plasticity is a good candidate as a heating mechanism during low-velocity impacts. [ABSTRACT FROM AUTHOR]

Magnesium alloys have gained importance for aerospace, automobile, and biomedical applications in the last few years due to their high strength to weight ratio. It is well known that magnesium possesses lower formability due to the insufficient slip systems available for deformation, especially during the forging process. There are many ways by which improvement in formability is possible. One of the methods is the refinement of grain structure and subsequently achievement of superplasticity by optimizing strain rate and temperature. The present article discusses the overview of the processing methods to produce fine grain structure in magnesium alloys. These methods include the conventional to severe plastic deformation processes. Conventional methods for refinement of grain structure include casting and hot rolling. Severe plastic deformation processes include caliber rolling, multi-directional forging, equi-channel angular pressing, high-pressure torsion, friction stir processing, and high ratio extrusion methods. The process described with associated equations for strain and the impact of these processes on the microstructural aspects of magnesium alloys is explained in this paper. It showed that the different process parameters with a different kind of alloy give rise to differences in the refinement of grain structures which further changes the formability of magnesium alloys. This paper also describes the advantages and limitations with usefulness in industrial practices of the processing methods to produce fine grain structure in magnesium alloys. [ABSTRACT FROM AUTHOR]

The paper investigates the fracture of the target plate under shock-wave loading. The material of the target plate is orthotropic organic plastic. The compression wave was generated on organic plastic using an aluminum striker plate. The velocity of interaction varied from 100 to 400 m/s. The study is carried out numerically by the finite element method in a three-dimensional statement using the author's software EFES. An elastic-brittle model is proposed to describe the behavior of the composite. A tensor-polynomial criterion of the second degree is used as a criterion of the fracture of the composite. A two-stage model is proposed to describe the fracture of the orthotropic material of the target plate. The model of the behavior of the composite takes into account the different modulus of strength properties in compression and tension. The behavior of the material of the striker is described by an elastoplastic medium, for the fracture of which a deformation criterion is proposed according to the limiting value of plastic deformation. The influence of the direction of reinforcement of the composite on the fracture of the target plate was studied. [ABSTRACT FROM AUTHOR]

With increase in day-to-day demand in automobile the rate of accidents is also being increased on daily basis. To ensure the safe journey of the passengers, the overall vehicle structure should have enough strength to withstand the impact load caused due to collision of vehicle with other objects. The car crash is a transient non-linear phenomenon which undergoes a huge plastic deformation at the time of collision. The design of car should be carried out to understand the structure deformation under impact loading. In the present paper, we have carried out the crash test analysis with the help of simulation software. Using Finite Element Analysis software various load cases are executed to check the safe design of automobile. The results of car crash analysis is used to estimate the maximum stress concentration and the total deformation caused due to impact. Different materials were tested for the same design and choice of the better performing material can be made based on mechanical properties. Results of the car crash test indicates the Aluminum based alloy is performing better in car crash test. [ABSTRACT FROM AUTHOR]

Based on a performed analysis, an analytical method is proposed in the paper, for determining the accuracy during processing, taking into account the mutual influence of the components of the total inaccuracy. This is of particular importance in the processes of finishing treatment, such as surface plastic deformation (SPD), where technological heredity and the formative technological environment play an important role in forming the quality of the finished part. The matrix approach is applied, describing most fully the mechanism of formation of the constituent inaccuracies, taking into account the phenomenon of "technological heredity". The sequence for determining the transformation coefficients is given, by which the degree of mutual influence of the constituent inaccuracies in the interaction of the workpiece with the technological environment at the level of an operation is shown. [ABSTRACT FROM AUTHOR]

The shock absorber is a key element of the car's suspension. Comfort, cornering stability and braking properties depend on its condition. In good condition, it must provide the necessary levels of damping for the relative displacement between the sprung and the unsprung mass of the vehicle. The reasons of a faulty shock absorber include a breach in the integrity of the seal between the different chambers, fatigue of the springs in the valve (piston) systems, plastic deformations in the working inner cylinder due to high temperature and mechanical stresses, etc. In the event of a shock absorber fault, usually there are no visual or noise changes to alert the driver. Therefore, the technical condition of the shock absorbers is often neglected. The visual inspection at annual tests of vehicle safety and roadworthiness does not give a satisfactory result. Expensive vibration stands are used to diagnose the technical condition of the shock absorbers, which also repels maintenance centers from such a purchase. The paper presents a comparative method that determines the technical condition of the shock absorber. For this purpose, the free damped oscillations of the sprung mass are recorded with measuring equipment at an affordable price. The measuring equipment includes an accelerometer, a DAQ-module and a laptop. The tyre is disturbed in the contact patch by artificial obstacles. Based on the logarithmic decrement of the oscillations, the damping coefficient of the suspension system is determined. Its value is an indicator for the technical condition of the shock absorber. [ABSTRACT FROM AUTHOR]

The paper discusses systems with seismic isolation in which the seismic support part consists of an elastic element and friction one connected in series. The friction element is modeled with a dry friction damper. Only the elastic element works in the system at small vibrations, and at peak loads, slippage occurs in the dry friction damper. In this case, the load on the superstructure and the substructure is limited by the friction force in the dry friction damper. The harmonic oscillations of the considered system have been analyzed. At the same time, three possible modes of system behavior have been established. The first mode with a weak impact far from resonance is characterized by a purely elastic isolator behavior. The second, more dangerous mode is characterized by large plastic deformations at the initial impact stage. Still, after several cycles of plastic vibrations, the system adapts to the seismic impact and vibrates elastically. In this case, a progressive collapse of the system is possible at the first stage of loading. Finally, the third mode is characterized by plastic deformations at the initial stage of loading and during steady-state vibrations. In this case, progressive collapse at the first stage and low-cycle fatigue at the second stage of the system operation are possible. The necessary values of the friction force and damping in the system, excluding dangerous resonant vibrations, is to be more than 10% of the structure weight. [ABSTRACT FROM AUTHOR]

This paper describes the design and operation of the bench developed for testing samples of welded structures for resistance to fatigue fracture. It is shown that parameters such as the maximum fracture load, crack length and geometric dimensions of the sample for the fracture equation must be determined experimentally. The results of studying steel samples to determine fatigue fracture are presented. In the course of experimental studies, it was found that the samples with the maximum hardness have the greatest tendency to established fracture, and an increase in preliminary plastic deformation leads to a significant increase in the ability of the samples to established fracture. Based on the results of testing on the developed stand, it is possible to predict the performance of the investigated products as a whole. [ABSTRACT FROM AUTHOR]

The paper analyzes the relationship between the parameters of deformation facets formed as a result of the passage of a localized shear band or slip band through the initial medium- or high-angle grain boundary during plastic deformation of polycrystalline materials. Two models of facet formation are proposed: a discrete model in which the deformation in the band occur by the movement of lattice dislocations in parallel slip planes and a model in which the deformation is considered as the movement of continually and uniformly distributed virtual dislocations in the band. The dependences of the strength of mesodefects forming on deformation facets as a result of the passage of shear bands on the crystallographic and geometric parameters of the model are obtained. [ABSTRACT FROM AUTHOR]

Plastic deformation is one of the most important ways to improve metals and alloys' physical and mechanical properties. Many such treatment methods have been developed, but the opportunities provided by the temperature decreasing during deformation into the cryogenic region are being ignored. Despite the effectiveness of cryodeformation, work in this direction is practically not carried out today. There is reason to assume that the researchers are stopped by fears of the complexity of the implementation of such deformation treatment. There is a small number of published works dedicated to this direction, since, unfortunately, the following factors of cryodeformation applicability were not critically considered: the range of materials for which this type of plastic deformation provides the maximum effect, the complexity of equipment for such deformation. This paper discusses the problems of cryodeforming under all-around compression (barocryodeformation), methods, and features of its implementation. A new method of cryodeformation is proposed – cryo-upsetting under all-around compression, which, together with cryoquasihydroextrusion, significantly expands the possibilities of barocryodeformation of metals and alloys. [ABSTRACT FROM AUTHOR]

Upset forging is a forming process in which material is plastically deformed under great pressure into high strengths components of different sizes. The plastic deformation takes place by heating a particular length of component in an induction furnace at 0.4Tm temp i.e. at recrystallization temperature required for upset forging (Tm means melting temperature of material). After heating the particular length of the component to this temperature, the component is hammered into a forging die. For achieving 0.4Tm temperature there is a huge consumption of power in induction furnace for S.S. 410(AISI) material. It will not only affect the production cost but also reduce productivity. So there is a need to optimize power in upset forging. In order to optimize power, the basic parameters need to be analyzed in the induction furnace i.e. heat losses occurring due to coil, radiation, and heat required for a heating particular length of the component. This paper primarily focuses on the reduction of flash allowance by considering cross-sections of the desired length of pin material which ultimately leads to power optimization. [ABSTRACT FROM AUTHOR]

Numerous empirical and numerical studies have been carried out on the mechanical characterization of ductile materials. The application of digital image correlation (DIC) equipped with three-dimensional measurement analysis was used to examine the mechanical characteristics of aluminum alloy (AL 7075). Then, the DIC outcome with finite element simulation results will be compared with the experimental results to measure the performance of the DIC. A tensile specimen of AL 7075 is tested under constant loading with a 2 mm/min displacement rate until fracture. Strain gauge and extensometer are used along with DIC monitoring technique to capture the structural deformation of the specimens. The specimen and test are simulated in ABAQUS software, in which the results are compared with experiment and DIC data, indicating a good correlation between the results. Limited data in the form of average deformation and strain of the experiments are not applicable to the plastic and necking process. In this respect, the 3D DIC results are used to analyze the strain field throughout the test, including specimen necking, and predict fracture location. Moreover, the outcome of DIC and finite element simulation are employed to examine the characteristics of AL 7075 about the large plastic deformation and mechanical behavior. The proposed 3D DIC methodology in providing insight into the characteristic mechanical behavior of ductile materials is highlighted in this paper. [ABSTRACT FROM AUTHOR]

Cold Roll Bonding (CRB) is recognized as an industrial technique in which the metal sheets are joined together in order to produce laminate metal composites. In this technique, a metallurgical bond resulting from severe plastic deformation is formed between the rolled metallic layers. The main objective of this paper is to analyse different factors which may affect the bond formation in rolling processes. To achieve this goal, first, an interface model is employed which describes both the bonding and debonding. In this model, the bond strength evolution between the metallic layers is calculated based on the film theory of bonding. On the other hand, the debonding process is modelled by means of a bilinear cohesive zone model. In the numerical section, different scenarios are taken into account to model the roll bonding process of metal sheets. The numerical simulation includes the modelling of joining during the roll bonding process followed by debonding in a Double Cantilever Beam (DCB) peeling test. In all simulations, the metallic layers are regarded as elastoplastic materials subjected to large plastic deformations. Finally, the effects of some important factors on the bond formation are numerically investigated. [ABSTRACT FROM AUTHOR]

The paper deals with numerical analysis of shear banding which occurs in an elongated rectangular plate for a large strain elastic-plastic material model. It is focused on the influence of plate size proportions and finite element mesh density on numerical results. The discussion is limited to isothermal conditions and ideal plasticity. First a plain strain case is computed for different lengths of the plate, then simulations are repeated for plane stress for which different thicknesses of the plate are considered. Most of the computations are performed for three finite element meshes to verify discretization sensitivity of the results. The simulations are performed using AceGen and AceFEM packages for Wolfram Mathematica. [ABSTRACT FROM AUTHOR]

Calculations of reinforcement of "D" regions of reinforced concrete structures is much d ifficult than for "B" regions and demands some specific approaches. Authors of the paper suggest to use both Strut-and-Tie (S&T) and Finite Element Method (FEM). The first of those methods allows to calculate required reinforcement and efficiency factor. In turn FEM can not only confirm S&T results but also gives information about crack width and pattern, strains and nodal displacement. Sample calculations were performed on example of frame corners under opening bending moment. Parameters of Concrete Damaged Plasticity model of concrete implemented in Abaqus were calibrated in tension and compressions test. [ABSTRACT FROM AUTHOR]

This paper examines fracture toughness in deteriorating concrete viewed as exhausting resource of normalized freeze-thaw resistance. The analysis is based on laboratory tests for axial compression of concrete prismatic samples un- dergone staged cyclic freezing (-42°C) and thawing. Employing statistical trends, the study shows the kinetics of sam- ples' values identifying their strength characteristics (ultimate strength and upper-bound value of micro-fractures) and de- formation properties (ultimate and maximum values). The applied method defines fracture toughness indicator as a share of energy absorption for plastic deformation in the total fracture energy capacity. Freeze-thawing cycles (FTC) with in- creased dynamics of impacts exceeding the level of normalized frost resistance show a steady decline in the fracture toughness. The research proposes a probability-based approach to the analysis of kinetics of fracture toughness. [ABSTRACT FROM AUTHOR]

The paper considers a submodel of the statistical multilevel model of deformation for polycrystalline materials. The model is based on a physical plasticity approach and allows one to describe the deformation of polycrystalline metals taking into account the density of defects on crystallographic systems: edge dislocations on slip systems, sources of dislocations, barriers on split dislocations. An additional hierarchical level has been introduced—mesolevel-2, where the homogeneity of defects for prescribed slip systems is taken. As main mechanisms of plastic deformation slip of intragranular dislocations is considered. Particular attention is paid to the description of the evolution of defect densities – the formation of new dislocations and barriers, as well as their consideration in the hardening law. The results of numerical calculations for uniaxial and complex loading are in agreement with the experimental ones, and the role of the main mechanisms of hardening in the course of plastic deformation is analyzed. [ABSTRACT FROM AUTHOR]

The paper studies the deformation behavior of nitinol in a superelastic state at the macroscopic level. It has been established that both the direct phase transformation B2 → B19' during loading and the reverse phase transformation B19' → B2 during unloading are realized through formation of moving fronts, which are localized plastic deformation switching autowaves. The relationship between autowave propagation velocity during loading and the gripping device speed is investigated. [ABSTRACT FROM AUTHOR]

The need for impact energy-absorbing modules in the application of structural crashworthiness is essential. Various alternatives of energy absorbing mechanism based on plastic deformation are presented by numerous investigators, since 1970s until recently, with various application, particularly for vehicles. This paper presents on-going research report on the proposed mechanism that combines two effective plastic energy-absorbing mechanisms, i.e., tube inversion and axial splitting. Both mechanisms provide nearly ideal behaviour of flat force versus displacement characteristics but with its subsequent drawbacks. The previous tube inversion mechanism has less stroke efficiency, whilst current axial splitting mechanism has relatively low response force, hence absorbed energy. By combining the two mechanisms, it is hoped to overcome the drawbacks of each mechanism. Early work on the proposed combined mechanisms has been presented elsewhere. Here, further study is reported with the main objective of establishing the relationship between dimension ratios and impact performance of the new mechanism under development. Parametric study is carried out based on finite element analysis with dynamic plasticity capability using ABAQUS general purpose finite element analysis software, for a number of cases. The geometry parameters selected are pipe dimensional ratio D1/t, and die dimensional ratio D2/D1, with the same material used, that is structural pipe steel API 5L. The numerical result is validated using experimental result. The result is presented in the relationship between geometry parameters (D1/t and D2/D1) and impact characteristics, i.e., force-displacement curve, energy absorption, and stroke efficiency. The study also presents precautions on certain geometry parameter combinations that yields unwanted deformation. The proposed mechanism by combining the two existing mechanisms is new with improved performance and has a potential application on high-capacity impact energy absorption such as in railway vehicles. [ABSTRACT FROM AUTHOR]

A paper considers mathematical model, numerical method and its software implementation on GPU for the simulation of the development and localization of plastic shear bands in a poroelastoplastic solid. A mathematical model of the process is described by a system of nonlinear partial differential equations of poroelastoplasticity, generalizing the Biot model for a two-phase fluid-saturated poroelastoplastic medium. A nonlinear dependence of material parameters on a dynamic porosity, which, in turn, depends on the volumetric deformation of the skeleton, is taken into account. For the numerical solution of the posed problem an isoparametric spectral element method is used to discretize a geometric model and poroelastoplastic equations in space on curvilinear unstructured meshes. A dynamic relaxation method is used to obtain a stationary solution of the boundary value problem using an explicit time scheme, which leads to a high scalability of the computational process when parallelizing the algorithm on massively parallel GPU. The algorithm is implemented using CUDA technology. A spectral element mesh is naturally mapped onto the CUDA Grid, and accordingly, each spectral element is mapped onto a CUDA Block, so local nodes inside a spectral element are processed by the threads in the Block. This approach allows efficient use of the shared memory for data caching in the Block and significantly increase the throughput of the parallel algorithm, which is essentially memory bound. Numerical results of the simulation of the development and localization of plastic shear bands nearby a borehole drilled in a porous fluid saturated solid are presented. Evolution of porosity and permeability as a result of the accumulation of plastic deformations is analyzed. [ABSTRACT FROM AUTHOR]

In this paper, the acoustic emission (AE) under static tension of Pb-Sn alloys is studied. It is revealed that the Kaiser effect is not observed under repeated loading of the material at component concentrations leading to the formation of a eutectic structure. The Principal Component Analysis (PCA) is utilized to extract and analyze the amplitude and frequency features of AE signals. Registered AE signals are divided into blocks to extract the informative parameters as feature vectors representing amplitude and frequency features of the registered AE signals. Processing results help clarify the influence of plastic deformation on the studied phenomenon. Obtained results can be used to analyze acoustic emission testing results of various materials under plastic deformation and study the deformation behavior of materials. [ABSTRACT FROM AUTHOR]

The paper presents the results of studying the characteristics of fracture resistance of promising 26KhMFA pipe steel in the range of climatic operating temperatures. It was found that the steel under the study has high indicators of both mechanical strength and resistance to fatigue crack propagation in the temperature range from +20 to −70°C. Studies of the phenomena accompanying the crack growth on the lateral surface of CT-specimens have been carried out. It is shown that with a drop in the test temperature, the area of the localized plastic deformation zone at the fatigue crack tip decreases with a simultaneous microhardness increase within this zone. [ABSTRACT FROM AUTHOR]

This paper numerically investigates the physical behavior of deep geological structures in the Yakutsk-Vilyui large igneous province. The geophysical data of "Kimberlit-1981" profile was used to create the computer structures of the researched region. To analyze the plastic deformation, the Nikolaevskiy elastic-plastic model was used. For investigating the geotectonic stress processes, the strength model "jelly sandwich", which operates with cohesion and coefficient of internal friction, was adapted to the Nikolaevskiy model. The depth analysis of plastic strain and the stress state was performed. It is shown that the strain localization partially accord with the orientations of faults obtained from the geophysical data of "Kimberlit-1981. The distribution of stress state is conditioned by the model "jelly sandwich". The distribution of pressure has a quasi-monotonic increase with depth and local disturbances caused by strain localization in the shear bands in the depth layers of Earth's crust. These results can be of use by geologists to evaluate the metamorphism of rocks. [ABSTRACT FROM AUTHOR]

Thermo-mechanical numerical modelling and simulation of extrusion processes faces several serious challenges. Large plastic deformations in combination with a strong coupling of thermal with mechanical effects leads to a high numerical demand for the solution as well as for the handling of mesh distortions. The two numerical methods presented in this paper also reflect two different ways to deal with mesh distortions. Lagrangian Finite Element Methods (FEM) tackle distorted elements by building a new mesh (called re-meshing) whereas Arbitrary Lagrangian Eulerian (ALE) methods use an "advection" step to remap the solution from the distorted to the undistorted mesh. Another difference between conventional Lagrangian and ALE methods is the separate treatment of material and mesh in ALE, allowing the definition of individual velocity fields. In theory, an ALE formulation contains the Eulerian formulation as a subset to the Lagrangian description of the material. The investigations presented in this paper were dealing with the direct extrusion of a tube profile using EN-AW 6082 aluminum alloy and a comparison of experimental with Lagrangian and ALE results. The numerical simulations cover the billet upsetting and last until one third of the billet length is extruded. A good qualitative correlation of experimental and numerical results could be found, however, major differences between Lagrangian and ALE methods concerning thermo-mechanical coupling lead to deviations in the thermal results. [ABSTRACT FROM AUTHOR]

The paper represents the results of a study concerning the high-speed interaction of natural and technogenic particles with aluminum, glass and glass-reinforced laminate targets of finite thickness. These materials are widely used as the structural elements of spacecrafts such as spacecraft bodies, tanks, windows, glass in optical devices, heat shields, etc. This paper considers the impact, deformation and fracture of aluminum, glass and asbestos-reinforced laminate samples with aluminum and steel particles which represent space debris and with ice and granite particles which represent the natural particles of space bodies [ABSTRACT FROM AUTHOR]

Corrugated sandwich plates are widely used in marine industry because such plates have high strength-toweight ratios and blast resistance. The laboratory-scaled fluid-structure interaction experiments are performed to demonstrate the shock resistance of corrugated sandwich plates by quantifying the permanent transverse deflection at mid-span of the plates as a function of impulsive loadings per areal mass. Sandwich structures with 6mm-thick 3003 H18 aluminum corrugated core and 5A06 face sheets subjected to underwater impulsive loadings are studied experimentally in this paper. The dynamic deformations of plates are captured with the the 3D digital imaging correlation method (DIC). The results affirm the peak deflection during the processes of dynamic deformation and the residual maximum deflection for post-mortem plates show a linear trend with the impulses per areal mass, and show sensitivity to the change of impulses. Inhomogeneous deformation for corrugated sandwich plates are show uneven rather than the perfect parabolic shapes reported in previous studies. With the increasing of intensities for impulsive loadings, the failure modes can be observed more complicated from the initial plastic deformation to debonding and crack. This paper provides valid data to quantify the peak deflection, residual deflection and failure modes as functions of impulses and geometric parameters in the future work. [ABSTRACT FROM AUTHOR]

Mechanical clinching is recognized as a promising industrial technique to join dissimilar metal sheets by cold forming. In this technique, the metallic layers are joined by local hemming with a punch and die. The present paper aims at providing a finite element model for the mechanical clinching processes. To accomplish this, a locking-free element formulation (Q1SP) is employed which is essentially based on the reduced integration technique with hourglass stabilization. The performance of Q1SP element against locking is first demonstrated through a benchmark test. Then, a finite element model for the clinching process is developed. It is shown that the Q1SP element can efficiently reproduce the severe plastic deformations observed in a real clinching process. The results obtained by the FE model are then compared with experimental data. Additionally, the performance of the employed element is compared with the standard Q1 element. It is also shown that the standard Q1 element exhibits an artificial stiffness which may result in the underestimation of mechanical interlocking value. This deficiency can be adequately overcome by applying the Q1SP formulation. [ABSTRACT FROM AUTHOR]

Creasing is a method, which is used to produce grooves in fibre-based materials, such as multi-layer paperboard or composite materials such as polymer-coated multi-layer paperboard. These grooves act as folding lines, which guide and control the subsequent folding of the material. The formation of creases is crucial for the functionality of produced blanks in subsequent processes, such as press-forming where the creases have an effect on the formability of materials. The plastic deformation and geometry of creases for polymer-coated and uncoated multi-layer paperboard were investigated using two different creasing processes, flatbed die cutting and a digital creasing and cutting table with a creasing wheel. The presence and dimensions of the creasing grooves were varied to investigate the effect on the formed shapes. A wide area 3D measurement system was used to analyse and measure the dimensions of the formed creases. The results show that that the used process and tool selection has a clear effect on the formed shapes. Based on the results, recommendations for tooling selection are given. [ABSTRACT FROM AUTHOR]

The paper presents the innovative process with possibility of predict the state of deformation and stresses in a two-stage metal forming process. In the first stage, regular surface roughness with arched outlines are embossed. In the second stage, these inequalities are flat burnished to obtain the required dimensions, roughness of the surface, and state of deformation and stresses in the surface layer of the workpiece. The process are considered as a geometrical and physical non-linear boundary and initial value problem, with unknown boundary conditions in the contact zone. The applications were developed in the Ansys/LS-Dyna system, which makes possible a complex time analysis of the states of displacements, strains and stresses, in the workpiece in the two-stage cold metal forming processes. Application of this method were showed for examples the modelling and the analysis of the regular asperities with arched outlines. In the simulations, the material as well as the geometrical parameters of surface asperities were changed. The simulation results were verified experimentally. [ABSTRACT FROM AUTHOR]

The paper analyzes the dispersion of the mechanical parameters and its influence on the forming limit curves of sheet metals. The tests have been made for the case of the DC01 steel sheets. The dispersion of the mechanical parameters has been observed during the experimental research. On the basis of this dispersion, a forming limit band has been calculated using an alternate formulation of Hora's model (MMFC). [ABSTRACT FROM AUTHOR]

The paper describes damage-plasticity model for the modelling of the host rock environment of a nuclear waste repository. Radioactive Waste Repository Authority in Czech Republic assumes the repository to be in a granite rock mass which exhibit anisotropic behaviour where the strength in tension is lower than in compression. In order to describe this phenomenon, the damage-plasticity model is formulated with the help of the Drucker-Prager yield criterion which can be set to capture the compression behaviour while the tensile stress states is described with the help of scalar isotropic damage model. The concept of damage-plasticity model was implemented in the SIFEL finite element code and consequently, the code was used for the simulation of the Äspö Pillar Stability Experiment (APSE) which was performed in order to determine yielding strength under various conditions in similar granite rocks as in Czech Republic. The results from the performed analysis are presented and discussed in the paper. [ABSTRACT FROM AUTHOR]

We modify a theory of flow stress introduced in [6,7,8] for a class of polycrystalline materials with equilibrium and quasy-equilibrium defect structure under quasi-static plastic deformations. We suggest Maxwell-like distribution law for defects (within dislocation-disclination mechanism) in the grains of polycrystalline samples with respect to grain's diameter. Polycrystalline aggregates are considered within single-and two-phase models that correspond by the presence of crystalline and grain-boundary (porous) phases. The scalar dislocation density is derived. Analytic and graphic forms of the generalized Hall–Petch relations for yield strength are produced for single-mode samples with BCC (a-Fe), FCC (Cu, Al, Ni) and HCP (a-Ti, Zr) crystal lattices at T=300 K with different values of the grain-boundary phase. We derived new form of the temperature-dimensional effect. The values of extremal grain and maximum of yield strength are decreased with raising the temperature in accordance with experiments up to UFG region. [ABSTRACT FROM AUTHOR]