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Mechanical joining processes provide various advantages over conventional fusion welding of metallic components such as shorter cycle times, little or no heat input and reduced need for subsequent surface finishing operations. Several investigations in the past have shown that joints between tubes and sheets or plates can be manufactured by upsetting operations. Under axial compression, the tube develops a plastic instability in form of bulge. In-between two such bulges, a force and form fit to sheet material can be created. Previous work concentrated on forming fully developed bulges, i.e., at the end of the bulging process, both hinges of the bulge are in contact. This paper presents a numerical and experimental study aiming at optimizing the bulge shape to increase the bearable limit loads. Two new bulge designs are investigated, an ‘arrow bulge’ and a ‘wave bulge’. The paper details the results of FE-simulations of the bulge shapes under bending and torsion loads. Forming tools were designed and both bulge shapes were produced experimentally. The results show that the material flow under compressive plastic instability can be controlled and that the resulting bulge shapes yield improved strength in various load cases. [ABSTRACT FROM AUTHOR]

The paper presents a methodology of testing the mechanical properties of fibrous materials belonging to the group of natural polymers. The research methodology includes the process of aging in a controlled humidity atmosphere using a climatic chamber. The paper presents the results of the degree of compaction of the shredded coconut material and sediment post-fermentation fiber as a function of humidity. We have also studied the friction coefficient of the compacted material in depending on the influence of temperature. The results are the basis for determining the parameters of agglomeration of the tested materials. In addition results are essential to determinate effective forces of compaction which are used for the formulation of construction of machines for this purpose. [ABSTRACT FROM AUTHOR]

The study of the mechanical behaviour of gabion elements is a fundamental prerequisite for an improved understanding about the overall mechanical performance of retaining structures realized using this construction technique. The paper discusses the first part of a wide experimental research program. The current article is limited to the description of the modalities to define a comprehensive experimental campaign, which involves both compression and direct shear tests. The testing matrix is designed considering several variables related to the two main components of the basic constructive element, steel cage and filling material respectively. The setup of instruments and the testing procedure are also discussed in the paper. [ABSTRACT FROM AUTHOR]

The paper deals with computational modeling of radial tire for cars. The authors used FEA (Finite Element Analysis) utilizing program ANSYS. The authors are oriented not only to the strain-stress analyses of tire. In relation to the tire computational models, the composite structure parts (textile carcass, steel-cord belt and textile belt) cannot be implemented up to the level of reinforcing cords because of the time difficulty as well as the large number of the finite elements. The composite structure parts are partially replaced with some specified stiffness. The paper describes the different ways of replacement of structure represented by the steel-cord belt. These replacements are used for FEA of tire. [ABSTRACT FROM AUTHOR]

The paper presents a methodology of tests of mechanical properties of natural polymers. Aging test of polymers in an atmosphere of high humidity by using the climate chamber was discussed. The effect of humidity value changes on the degree of compaction was researched for different degrees of humidity. Next part of the paper presents the results of determination of friction coefficient of agglomerated natural polymers. The values of friction coefficient were calculated for different values of polymer temperature. The temperature values were similar to the values of temperature for polymer during agglomeration process. [ABSTRACT FROM AUTHOR]

The introduced paper is closely connected with the whole complex of problems which arise due to the effect of poor-quality or imperfect structure of such materials which are used for production of implants while the embedment of living human tissue cells to the mentioned implant is one of the most required conditions. The given paper as well as investigation is mainly focused on detailed analysis of technological modification and resulting structure relating to selected human implant. Generally, there is the occurrence of unacceptable structures or conditions for determined microareas if the all of the required criteria for the primary crystallisation of the specified alloys are not kept. In relation to the mentioned microareas, the embedment of the living human cells is different in comparison to the embedment of the living human cells in homogeneous structure and therefore, considering the implants and embedment of living human tissue cells, there is the real menace of occurrence of undesired tissue interactions with the deteriorative and unacceptable elements (O, H, S, N) and this phenomenon can be the reason for necrosis or abnormal and uncontrollable growth or multiplication of cells. [ABSTRACT FROM AUTHOR]

The paper deals with the basic requirements on structural properties combined with material properties for computational modeling of train brake shoes. It is a construction element consisting of base material made of graphitic cast iron and reinforcing steel insertion of simple geometric shape. The structural unit of a “brake shoe” must be functional during train wheels braking. Therefore, it is necessary to design a computational model allowing to simulate operation load and to predict future failure. Because of that, this paper focuses on structural properties with an impact on the construction unit material properties required for computational modeling. Manufacturing technology affects the quality of the final structure whose character may be the cause of the failure initiation. In the presented paper, authors aim to investigate in detail the structure and its imperfections lowering the required properties. These are the factors necessary to take into account in computational modeling of the simulated operating load of the given construction element. [ABSTRACT FROM AUTHOR]

The paper deals with propagation of defects and separations in tyres which are under dynamic load. The initiation and distribution of the defect has the significant influence on lifetime and quality of the tyre when the tyre is in service as a part of the vehicle and avoidance to the initiation and distribution of the defect can improve the safety on the road. The analysis mentioned in previous projects enabled us to solve critical conditions and problems in relation to tyre casing while the investigation and solution included material selection, suitability of individual components proportion as well as the whole construction of the tyre casing. The main goal of this paper is closely connected with the presentation of the continual work. The reason for detection of internal separations in tyre casing is to avoid usage of those tyres, which already contain some internal separation about which we know that it could propagate during the movement of vehicles. This is closely connected with occurrence of tyre destruction and the main purpose is to prevent of its critical status and later vehicle crash and human life menace. [ABSTRACT FROM AUTHOR]

Realkalisation treatment was used to recover carbonated concrete alkalinity nearby the reinforcing region at normal temperature. The feature of the realkalisation treatment which could restore concrete high alkalinity is applied for the neutralization of concrete suffered from high temperature in this paper. This paper develops important data on the application of realkalisation treatment for the mechanical behavior and durability characteristics recovery of fire-damaged high strength concrete. In this paper, the compressive strength of fire-damaged high strength concrete before and after realkalisation was investigated. The test results indicated that the realkalisation treatment results in compressive strength recovery and its effect extent depends upon exposure temperature, current density, treatment time and concentration of electrolyte. When compared with the original unfired values, the residual compressive strengths of tested specimens of cube compressive strength of 71.2 MPa exposed to temperature from 300 °C to 700 °C for two to three hours ranged from 80.3% to 39.7%, their recovered strengths were 89.6% to 61.4% after 7 days treatment. Compared with obtained experimental results of fire-damaged tested specimens of cube compressive strength of 50.2 MPa, the effect of recovered strengths is better for lower compression strength of compression cube. [ABSTRACT FROM AUTHOR]

Ball burnishing has proved to be a highly effective mechanical finishing process of industrial workpieces, because of the excellent surface roughness and fatigue performance that induces in treated workpieces. In order to obtain specific target results from this complex plastic deformation process, its parameters must be accurately controlled. This paper focuses on the influence of the lateral pass width on the average surface roughness of aluminum 2007. Two values of lateral pass width are tested, with two control variables: number of burnishing passes and applied burnishing force. Furthermore, the ball burnishing operation is performed with two different tools: a conventional non-assisted ball-burnishing tool, and a vibrations-assisted one. The most suitable lateral pass width proves to be the distance between the highest peak and lowest vale of the P-profile of the burnishing path, and significantly better results are obtained by assisting the process with vibrations. At the end of the paper, values for lateral pass width for each group of operation conditions are recommended. [ABSTRACT FROM AUTHOR]

In this paper, the problem of accuracy control of machined complex profiles is investigated. Presented are schemes of the mechanical load of the cutting tool as a function of the current angle of the machined profile. A simple method for compensating the profile error caused by mechanical deformations is suggested. Presented is an algorithm for the automatic measurement of the machined profile and for the compensation of the profile error. [ABSTRACT FROM AUTHOR]

In recognition that pressure equipment welds that have not undergone a full volumetric inspection may contain internal defects, a weld efficiency is introduced. For spot volumetric inspection which is typically 10% of the weld length the weld efficiency is taken as 0.85. Of interest is that this factor is universally adopted in all known pressure equipment codes around the world. Its origins are obscure and to the authors’ best knowledge, has gone unchallenged for the past 88 years. Additional interest is the use of 0.7 weld efficiency for a weld that has undergone no volumetric inspection. This is prevalent in many international pressure equipment code, but not all. This paper revisits these factors. It considers how they were developed and explores a more rigorous probabilistic approach based on the amount of volumetric inspection and the likelihood of defects. It also considers the closely associated design factors. Understanding also that weld technology has developed since the early 1900 and in particular with the introduction of new technologies such as submerged arc welding, it may not be unreasonable to expect these weld efficiencies to differ from that initially developed. While the paper is not conclusive in its findings, it highlights there is justification to question the weld efficiencies adopted and proposes a program to develop more rigorous values. [ABSTRACT FROM AUTHOR]

This paper investigates effect of thermal aging on reduction of fracture toughness of CF8 M cast stainless steel. To predict fracture toughness of un-aged and aged materials by numerical analyses, finite element damage analysis is used in conjunction with strain-based fracture model. The strain-based fracture models for un-aged and aged CF8 M are determined from notched bar tensile test data and finite element analysis of it. It is found that the effect of thermal aging on material ductility can be quantified with introducing the concept of thermal aging constant. Using the method in this paper, J -resistance curves for un-aged and aged CF8 M can be predicted and compared with experimental test data. [ABSTRACT FROM AUTHOR]

Heavy wall reactors and large diameter pressure vessels usually face unique challenges in their erection onto their foundations at the jobsite. Today, 800 ton to 1,500 ton reactors and or large diameter vessels with diameters ranging up to 15 meters are common in the refining industry. These pressure vessels are usually fabricated in shops dispersed globally and require unique heavy duty equipment for their safe handling, transportation and erection. The challenge is to find a safe, efficient and cost effective solution based upon the limitations of the equipment, job site and the lift equipment available for erection. Equipment for the handling heavy reactors and large diameter pressure equipment is usually scarce, expensive. Planning well in advance of the lift date is required. Careful consideration must be given to the choice and design of attachment to the pressure vessels used for the lift to ensure that the vessel and lifting components are not overstressed during the lifting process. This paper identifies the types of evaluations that must be performed to determine the stresses in the vessel and lifting attachments during the lifting. The paper also discusses different types of lifting lugs that may be attached to each end of the vessel either by bolting or welding and discusses the pros and cons of each. The paper also provides an example of a finite element analysis (FEA) of a top nozzle, a FEA of a pair of lifting trunions and a FEA of welded on lifting lugs for buried pipe. The intent of the paper is to outline the effects on the vessel due to different types of lifting configurations in combination with the lifting parameters. This paper is not intended to provide guidance on how to design lifting lugs. [ABSTRACT FROM AUTHOR]

With the development of petroleum, chemical and energy industries and urban gas network, the amount of pipelines in China has grown rapidly in recent years, meanwhile it leads more accidents. The main reason is that some pipelines have gradually served into their late period or even extend period of the pipeline design or expect life. However, we usually cannot use conventional destructive test methods to measure the performance of pipelines in service, so that we cannot make an accurate assessment of the remaining life of the pipelines. This brings serious challenge to the safety management of pipeline transportation in China. In order to investigate a new method to non-destructively test the mechanical properties of pipe steels, the yield strength and tensile strength of pipe steels including low carbon pipe steels 20, the low carbon micro-alloyed pipe steel L415, L360, and stainless pipe steels used in China were measured through the methods of continuous ball indentation test and conventional tensile test in this paper. The measured results by the destructive and non-destructive test methods were compared and analyzed in detail in this paper. It is concluded that the continuous ball indentation test method can be used to measure the yield strength and tensile strength of pipe steels feasibly and accurately. [ABSTRACT FROM AUTHOR]

This paper presents a procedure to predict fracture toughness of steel material using small punch test (or notched small punch test) and finite element (FE) damage analysis. Tensile property can be determined from setting the constitutive equations and can be validated by comparing the small punch (SP) test data with FE results applying the determined tensile property. FE damage analysis used in this paper is based on the strain-based fracture model. Material constants in the model are normally determined from analyzing notched bar tensile tests. To determine these material constants from SP test instead of notched bar tensile tests, simplified model (with only one material constant) can be introduced and used in the simulations. SP test and notched small punch (NSP) test are simulated via FE damage analyses using the tensile property and simplified strain-based fracture model. NSP simulation results are sensitive to element size. However, SP simulation results are not sensitive to element size. Compact tension (C(T)) test is also simulated and it can be found that the proper element size for C(T) simulation is four times of that for NSP simulation to predict cracking initiation toughness. [ABSTRACT FROM AUTHOR]

Beach erosions have been faced as coastal problem and efforts to address the solution have been sought by the coastal researchers. One of the coastal protection structures that are commonly used are the system of groins. Various types of groins have been investigated and observed either in the Laboratory or directly in the field namely type of the forming material, length of the groins, the distance between the groins, and the width of the groin. However, groins with a zigzag shape are rarely investigated and studied. Hence, this paper reports on changes in beach profile due to the construction of single zigzag type of porous groins named GROPOZAG. The small scale of 1:20 physical model tests have been carried out at the Laboratory of River and Coastal Engineering in Engineering Faculty of Syiah Kuala University. Regular wave were generated in wave basin with 15 m long, 5 m wide, and 0.6 m deep. The influence of single groin length ( L g ), and groins orientation perpendicular to the shoreline (θ) of 45°, 63°, and 90° under various wave steepness ( H/L ) of 0.0409, 0.0235 and 0.0200 with the beach profile of 1:20 slope are elaborated in this paper. Erosion or sedimentation is expressed in terms of sediment total volumes. It is found that groin with 90° orientation is more erosive than that of 45°. Straight porous groins erode more sediments than that of zigzag type porous groins. Zigzag porous groin is better in reducing erosion at the front head of the groin. [ABSTRACT FROM AUTHOR]

This paper presents test results of AA2519/TI6AL4V composite laminate structure and mechanical properties. The composite laminate was merged by explosive welding using a transition AA1050 alloy layer. Weld endurance properties were determined through fatigue testing performed in constant total deformation amplitude ( ɛ ac ) conditions. The paper also describes the influence of test conditions on hysteresis loop shape, process of cyclic material strengthening and weakening, and fatigue life. Low cycle test results were approximated using a straight line with the following formula: σ a = K′(ɛ ap ) n which enables the K′ fatigue strength coefficient, and the n′ cyclic strengthening index to be determined. Test results also include fatigue fracture surface analysis. Distinctive fatigue fissure characteristics were investigated through studying fatigue fracture surface microstructure using a scanning electron microscope. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigation according to which the optimal fraction composition of clay concrete from Taskala gaize is found out. Its physical and mechanical properties are taken into account. The optimal fraction for crushed clay concrete is as follows: 5-10 mm, 10-20 mm and 20-40 mm. The paper describes the influence of various technological factors on physical and mechanical properties of artificial crushed rock made from gaize. The role of preliminary thermal treatment of clay concrete particles and fractions is also looked into. According the results of the investigation the optimum thermal treatment temperature is stated. It's 200-3000°С for chert gaize and 400-4500°С for clay materials. [ABSTRACT FROM AUTHOR]

The paper deals with mathematical description of unilateral constraints imposed on displacements and velocities. Discrete mechanical system are analyzed. Mathematical description of the problem concerning the interaction between material points and unilateral constraints is presented. Unilateral constraints can be defined as a model of a phenomenon occurring during the process of interaction between a material body and a displacement restriction. It was assumed that the reaction forces characterizing this interaction are elastic and the body deformation is small comparing with its displacements. Mathematical description of constraints is composed of geometrical conditions imposed on the body motion as well as a relationship between the reaction force and the body configuration. In this paper, geometrical characteristics of constraints are described using multi-valued mappings. The study focuses attention on the formulation of the problem with the use of the concept of unilateral constraints described by variational inequalities. [ABSTRACT FROM AUTHOR]

The paper presents the research results of high performance modified concretes with complex hydrophobization modifiers and hydrophobic tragers. It is known that the concrete durability largely depends on its filtering characteristics, which can be lowered by adding hydrophobization additives to the concrete compositions, which, in turn, reduce the concrete strength and raise the concrete creep. The objective of the research was to develop a method of concrete hydrophobization without reducing its strength by applying hydrophobic water insoluble organic-and-mineral tragers. The paper provides the compositions of developed complex hydrophobization additives and water insoluble organic-and-mineral tragers. The influence of hydrophobization modifiers on the concrete workability has been studied as well. It was proved that complex hydrophobization modifiers allow producing high-mobility concrete mixtures and reducing their water separation value by 15…20% providing high preservation of concrete mixtures. The cube and prism strength values for concretes with modifiers are by 15…20% higher as compared to the concrete without additives. It was proved that the creep flow for all examined modified concrete samples was by 10…20% higher, and the concrete creep had damped characteristics. It was shown that the use of complex hydrophobization modifiers may reduce the water absorption as well as the capillary infiltration effect in concrete by 3…3.5 times. The concrete waterproofness is considerably improved as well; the waterproofness grade is almost 3 levels higher as compared to the concrete without additives. [ABSTRACT FROM AUTHOR]

The technology of sealing sand and gravel by chemical injection has been known and used for a long time. Chemical grouting is however expensive and sometimes the use of cement does not lead to the desired effect. That is why we are trying to find new materials and methods of injection. Clay and cement are added to a mixture save chemical products. Clay-cement mixes are used not only because they are better quality, but also because these mixtures have a tendency to penetrate better into incoherent sediments that would need an additional sealant of a chemical injection. In order to reduce cost in future, ordinary clay is replaces in the mixture secondary raw materials can be a suitable substitute for ordinary clay to a certain extent. This is true above all for fly ash. This paper deals with the appropriateness of using fly ash (secondary raw material), cement and lime (binders) and liquefying additives and examining their properties in the mixture. The aim of the paper is to propose the optimal injection mixture for additional sealing of earth dams. [ABSTRACT FROM AUTHOR]

The article presents the results of the investigation on the plastering mortars modified with lime and cellulose ether. Standard designations were performed and technological properties of plasters were determined. The performance of each plaster was rated, water retention ratio after 10, 30 and 60 minutes was determined and mechanical properties were described. An analysis of the effect of cellulose ether and lime on mortars’ setting and hardening time was performed by ultrasonic method. Rheological properties of the pastes concerning yield stress and plastic viscosity were determined as well. Although water retention for all mortars is at the same level, other parameters are highly varied. The results presented in the paper clearly show the effect of the cellulose ether and lime admixture on the standard properties and technological characteristics of both the material in the plastic state and the final product. The proper selection of the particular mortar components may have a decisive influence on the properties of the final product, therefore a comprehensive examination of the material is so important. The rating of the technical parameters of mortars presented in the paper can be a valuable source of information for contractors and construction materials producers. [ABSTRACT FROM AUTHOR]

Mesoscale modelling of porous materials may require building explicit geometric models for porous microstructure. Such microstructure models are composed of connected voids (pores) embedded in an otherwise impermeable solid. Having such a model at hand it is possible to directly calculate several characteristics of the pore microstructure, for instance pore radii, pore lengths, pore wall surface area as well as spatial distribution statistics. Additionally, having a solver capable of simulating fluid flow through such model, it is possible to gain insight into the effects of pore microstructure characteristics on flow properties, both macroscopic, such as permeability, or microscopic, such as tortuosity. In their recent paper Hyman and Winter [1] discuss an algorithm for stochastic generation of explicit pore structures by thresholding Gaussian random fields. Unfortunately their paper is missing an discussion on effective implementation of the presented algorithm. In our paper we fill this void by providing detailed discussion on implementation side of the algorithm discussed by Hyman and Winter. Besides presenting a microstructure generator which we provide as Open Source program, this paper shows how generated model can exported to data formats suitable for analysis and visualisation with various tools, for instance data formats based on VTK library. The programs described in this paper can form a base for handy tools and reduce the programming effort of building simulation environment for materials microstructure analysis. [ABSTRACT FROM AUTHOR]

The paper presents the evolution of the MATBUD conference and discusses the driving forces of research in the field of building materials. The paper attempts to interpret the trends in relation to the development of building material engineering. The approach adopted here is the investigation of the relation between material model and performance model as well as main drivers of building material research: idea, performance, research tools development, application and technological evolution. [ABSTRACT FROM AUTHOR]

No one can deny the role of synthetic polymers as engineering materials - they are all around us in our everyday life. Also due to the constant progress in material engineering, polymers, and among them elastomers, find increasing usage in civil engineering. Computer modelling of elastomers requires special description of material and use of non-linear finite element method. Available, free and commercial software use many different approaches in elastomers modelling, thus comparison of results may display discrepancies. Even if used method is the same, its computer implementation may vary, therefore using various software, one can obtain differing output. The paper presents comparison of results obtained from four computational packages devoted to FEA: Abaqus, GetFEM++, Tochnog, FEBio. It can be seen as an overview of the software that can be used in modelling rubber-like components. It highlights differences in material description (for instance in names of hyperelastic laws and employed formulas) and used multi-field variational principles in modelling material's incompressibility. Examples included in the paper can be treated as benchmarks, that can be helpful in verifying third party software or the one developed by readers. [ABSTRACT FROM AUTHOR]

This paper deals with the three-dimensional modeling of laminated glass failure due to delamination of the glass. The extended finite element method is used here (XFEM) to input discontinuity to the approximation field. The regarded glass consists of two outer glass plies and thin inner layer of the polyvinyl butyral (PVB). The PVB inner layer is very thin in comparison to the laminated glass thickness. That is why in the model, presented in this paper, the PVB layer is not spatially discretized. However, the inner layer exists in the problem formulation. The constitutive law for PVB is written with the help of two dimensional inner layer traction vector. Finally it results in three-dimensional effective numerical model for delamination analysis. The model is illustrated with an example. [ABSTRACT FROM AUTHOR]

The paper presents the evolution of the MATBUD conference and discusses the driving forces of research in the field of building materials. The paper attempts to interpret the trends in relation to the development of building material engineering. The approach adopted here is the investigation of the relation between material model and performance model as well as main drivers of building material research: idea, performance, research tools development, application and technological evolution. [ABSTRACT FROM AUTHOR]

This paper presents both experiments and associated numerical simulations of hypervelocity impacts (approx. 3000 m/s) of spherical aluminum projectiles onto hollow aluminum cylinders with either water or sand filling, which serve as representative filling substances for fluid and powdery materials, respectively. High-speed video technique is used to monitor the impact process. The paper mainly focuses on the following two subjects: (a) A direct comparison of failure and fracture of the container shell and the associated release of the filling depending on its type in both experiment and simulation. (b) With the above mentioned cases as reference examples, the applicability and efficiency of different numerical methods is investigated, such as Langrangian discretizations with Finite Element (FE)/Smoothed Particle Hydrodynamics (SPH) coupling, a coupled adaptive FE/SPH discretization and a coupled Euler/Lagrange method. The influence of the different simulation methods in terms of container failure representation and ejecta cloud properties is investigated and compared with the experimental results. [ABSTRACT FROM AUTHOR]

In the branch of forging presses there are new ones with direct drive. Our aim was to find out its possibility and to validate its properties and functionality. Mechanical forging single point press with a nominal force of 25 MN is selected for the example of direct-drive – this is a more powerful than was ever produced. The proposed direct drive is solved by pair of torque motors. These are connected with eccentric shaft via a gear drive, because of need to reduce speed. The paper gives the engineering process, including determination of the time of the stroke. We tried to discus a questions about efficiency in this paper. [ABSTRACT FROM AUTHOR]

Nowadays in die-cast manufacturing high speed milling are used to increase quality, accuracy and speed of material processing, also to reduce processing costs and save machining time. This paper is devoted for research of high-speed processing regimes impacts and their effect on the surface roughness quality of the machined material and 3D surface parameter values. This paper contains recommendations for die-cast manufacturers, deploying HSM, to improve machining process and obtain required surface quality. Analysis of variance methodology is used in this research. Research identify the most appropriate HSM regimes, that most important is chosen material type or material mechanical properties, influencing kurtosis of the scale-limited surface (Sku) and height of the bearing area ratio curve (Stp). Feed rate is most significant for texture aspect ratio (Str) and strategy type – influencing parameter of arithmetic mean surface height (Sa) and valley fluid retention index (Svi). [ABSTRACT FROM AUTHOR]

The passive modular groups mentioned in the classical theory of mechanisms are the basis modules in the construction of planar mechanisms with one degree of mobility corresponding to their linkages with four degrees of freedom. Even if thirteen solutions are presented [3–6] only some of them are found in practice and apparently there are groups never met in the mechanisms structure. The effectors extremity of bi mobile mechanisms describes any curve in an adequate domain. When the bi mobile mechanisms become main mechanical structures for robot arms and legs for mobile platforms two new notions are put into evidence - the inverse and the direct modelling. The inverse structure modelling of bi mobile mechanisms is based on the passive modular groups. By using the numerical operators such new structures with zero degree of mobility obtained from Baranov trusses may be obtained. In the paper there are also presented such new groups and their applying for the design of optimal bi mobile mechanisms. The paper is the result of intensive research to obtain new solutions applied and designed for various branches of robotics. The bi mobile systems thus obtained are patentable. [ABSTRACT FROM AUTHOR]

This paper is based on specific applications of Material Flow Theory (MFT) in industrial engineering material flow management (MFM). The accent is put on exploring different possibilities to increase productivity and profit in processing architectures using the MFM approach based on virtual modelling and simulation. In this context the paper presents a case study using virtual modelling of a flexible processing architecture and MFM simulation algorithms for diagnosis and optimization. The virtual model of the processing architecture will be used as a tool for identifying and eliminating the flow concentrators and obtaining an improved productivity of the system. [ABSTRACT FROM AUTHOR]

The paper focuses on an analysis of materials produced by modern classic additive method direct metal laser sintering (i.e. powder metallurgy). Direct metal laser sintering belongs to file of additive technologies of rapid prototyping. Rapid prototyping technology is a progressive group of methods used for fast creating of models, prototypes and components directly from 3D data. According to a used technology photopolymers, thermoplastics, specially modified paper or metal powders are used in rapid prototyping machines. Nowadays those production machines creates not only models and prototypes, but they are used to manufacture tools, forms and components for small series production. The purpose of the theoretical part is to gain in depth understanding of exactly what is the principle of direct metal laser sintering and what are properties of explored materials. The practical part analyses structures of materials used by classic and powder metallurgy. It concentrates on samples preparation, their analysis (using light and electron microscopy) and testing. Samples are analysed by mechanical tensile test and Vickers hardness test. The paper also compares sintered samples with steel equivalents produced by classic metallurgy giving final recommendation. [ABSTRACT FROM AUTHOR]

The paper presents comparative results of experimental researches on roughness parameters Rk and Rpk to sanding surfaces with wide belt and abrasive brush at the beech wood (Fagus sylvatica L.). The purpose of the research was to demonstrate that the sanding surfaces with abrasive brushes, offers the same surface quality, as wide belt sanding surfaces, where dusting and refinishing sanding operations were also conducted. The results lead to the optimization of sanding technology. [ABSTRACT FROM AUTHOR]

In this paper, a detailed investigation has been carried out to find out the impact of the process parameters including Tool rotational speed, welding direction at constant axial force and with a taper cylindrical pin profiled HSS tool during the Friction stir welding (FSW) of AZ31B magnesium alloy lap joints. This paper evaluates & examines in an elaborate manner, the influence of these FSW parameters in the microstructure & mechanical properties of AZ31B magnesium alloy. In short, AZ31B Mg alloys were friction stir welded by varying several different process parameters and the effects of these parameters on the joint quality, microstructure & mechanical properties were discussed comprehensively. This paper also experimentally proves & suggests the optimized process parameter values to be adopted for effective lap joining of AZ31B Magnesium alloys using FSW technique. [ABSTRACT FROM AUTHOR]

Spent fuel reprocessing plants of FBRs require advanced structural materials for service in aggressive conditions. Ti-5Ta-2Nb is a candidate structural material for electrolytic dissolver whereas 304L SS is used for rest of the plant. ‘Zero failure’ requirement for the process vessels necessitated the development of defect free explosive clad between Ti-5Ta-2Nb and 304L SS. The paper deals with the investigations carried out on the mechanical properties and microstructure of the explosive clads, and modification in microstructure on subsequent thermal exposure. The structural integrity of the clad as a consequence of these structure-property changes is also discussed in the paper. [ABSTRACT FROM AUTHOR]

A structural health monitoring system consists of permanently installed sensors to collect structural information, and these sensors are required to be placed at ‘good’ positions for damage identification. Conventional sensor placement methods make use of dynamic characteristics of a structure, i.e., mode shapes and natural frequencies, to determine optimal sensor positions. The engineering community has traditionally relied on these modal methods and finite element analysis for dynamic predictions in the low frequency range. However, these techniques become ineffective in mid frequency range due to large number of modes and high modal density. In view of this, in this paper, an optimal sensor placement technique which can be employed for low as well as mid frequency range structures for structural health monitoring as well as structural system identification is presented. The frequency domain based optimal sensor placement technique (FEfi) presented in this paper makes use of principal components evaluated from frequency response functions at the desired frequency levels. Numerical examples with optimally placed sensors dictated by the proposed algorithm are presented and compared with the popular effective independence (Efi) technique based on mode shapes. [ABSTRACT FROM AUTHOR]

The success of condition-based-maintenance (CBM) of mechanical components, in terms of cost and reliability, hinges closely on the ability to accurately estimate the remaining life of the components at point. In the case of rotary machineries, special attention for remaining life estimation is warranted in view of the dynamic behaviors associated with repetitive contact motions. This paper discusses the rotary machinery prognostics using rolling element bearing – one of the foremost causes of breakdown in rotary machinery – as an example to illustrate the treatments of self-leaning prediction of remaining life. To date bearing remaining life prediction issue has not been fully addressed, as a result of the highly random nature of the bearing defect growth behavior in fatigue cycles. This paper addresses the lack of current bearing condition monitoring techniques by proposing a remaining life adaptation methodology based on the approaches of mechanistic modeling of vibration and self-training of parameter adaptation, thus the instantaneous rate of defect propagation can be apprehended, even when the initial health condition is unknown and the defect growth behavior is time-varying, to deliver a reliable prediction of the remaining life. [ABSTRACT FROM AUTHOR]

Spent fuel reprocessing plants of FBRs require advanced structural materials for service in aggressive conditions. Ti-5Ta-2Nb is a candidate structural material for electrolytic dissolver whereas 304L SS is used for rest of the plant. ‘Zero failure’ requirement for the process vessels necessitated the development of defect free explosive clad between Ti-5Ta-2Nb and 304L SS. The paper deals with the investigations carried out on the mechanical properties and microstructure of the explosive clads, and modification in microstructure on subsequent thermal exposure. The structural integrity of the clad as a consequence of these structure-property changes is also discussed in the paper. [ABSTRACT FROM AUTHOR]

The present paper aims to develop a simple method based on inverse analysis that allows us to determine the laws of plastic flow coefficients and the friction coefficient between the material and punch. Selecting from different types of tests, we have chosen the Hecker test, because this test requires a single form of punch, the hemispherical one. In this test, the friction between the punch and the blank-sheet is caused by the blank-sheet strains and not by the movement it makes (as in deep drawing case). Besides the friction coefficient, other parameters like hardening and strength coefficients (n and k), influence the distribution of stresses and strains in the material. Using the Hecker test, we determined the curves force vs. displacement and major strain vs. displacement for three points located at different heights on the dome. Obtained from the test, these curves will stay on the basis of multi-criteria optimization analysis performed with LS-Dyna and Ls-Opt. The force vs. displacement curve was obtained using a hydraulic transducer and the major strains vs. displacement curves were obtained using the optical system Aramis which provides full information on the three-dimensional coordinates, displacements, strain variations, etc. On the other hand, using the Ls-Dyna software we will simulate the Hecker test and we will get the same types of curves (force vs. displacement and principal strains vs. displacement). Inverse analysis will consist in minimizing the “distance” between the curves obtained by simulation and experimentally obtained curves. We must to mention that this paper contains a big hypothesis: the identification is valid only for the chosen mesh and modelling of friction. [ABSTRACT FROM AUTHOR]

Stainless steel has been applied more and more extensively because it has good corrosion resistance and its surface is glossy, like a mirror after polishing. Thus, it is used in high-price pieces or quality goods. In this paper, the SUS 304 has been used to form a product with high expansion rate, via tube hydroforming technology, applying different feeding of two ends with different inner pressure to complete the procedure. The effects of different loading paths on product quality are discussed in this paper. Finally, by reasonable feeding with pressure parameters and a preforming process, a product with high expansion rate has been realized. The diameter-to-thickness ratio is 110, with an expansion rate of about 45%. The deviation of results from the experiment and simulation are also discussed in this paper. The results of this study could provide significant information to benefit industry. [ABSTRACT FROM AUTHOR]

Abstract: The paper deals with the problem of fatigue crack growth under variable-amplitude loading from a lifetime prediction viewpoint. A sequential Monte Carlo technique is employed to monitor crack propagation in presence of several uncertainties related to the material properties, measurement systems and environmental variability. The algorithm is able to estimate the most probable parameters describing crack growth data focusing on the most probable crack growth trajectories and enhancing the prediction of the residual life of the structure. Monte Carlo sampling allows accounting for the variable amplitude loading condition, simulating several crack growth evolutions using different loads and selecting the more appropriate for the actual crack evolution. The outcome of the algorithm that is the residual life prediction is used to appreciate the performances of the method. The end of the paper discusses the application of the method within structural health monitoring systems and lifetime predictor frameworks. [Copyright &y& Elsevier]

Abstract: Fatigue crack growth (FCG) could be encountered in many mechanical components, which can be made from either thin or thick steel plates (or shells) and, therefore, be subjected to a plane-stress or a plane-strain condition, respectively. The loads applied in a solid body containing a narrow notch or a sharp crack will induce a yield zone near its tip with a dimension that will depend on the mechanical properties of the material, as well as on the thickness of the body, the crack length and the magnitude of the loads applied. Crack propagation can then occur under mode I, II, III or mixed-mode for general loading. The paper presents JI, JII and JIII integral functions, which were correlated with the elastic stress intensity factors KI, KII and KIII, for thin and thick CT specimens. The evaluation of J-Integral values was carried out for different crack lengths, along the crack front, and using the Finite Element Method (FEM), with collapsed nodes and midside nodes dislocated to ¼ of the edge's length, in order to simulate the crack tip singularity. Interaction between in-plane, in-plane sliding and out-of-plane modes are also discussed in the paper. In addition, FCG rates under mode I, mode III and a mixed-mode (mode I+III) were experimentally determined, at room temperature, for a high-strength Cr-Mn austenitic stainless steel. [Copyright &y& Elsevier]

Abstract: Production of so-called superalloys is increasing in the present. This paper is about Inconel 738 LC. There are main mechanical properties as well as chemical composition of Inconel 738 LC in this paper. Special properties of superalloys cause, that they are very hard machining materials, mainly thanks to their high thermal stability during machining. For this reason it was necessary to measure the surface roughness after machining turbine blades made of Inconel 738LC depending on profiling. Roughing and finishing of Inconel 738 LC was used to get nearly the best parameters of the surface roughness. [Copyright &y& Elsevier]

Abstract: This paper describes experimental investigations of various mechanical properties of Ultra High Performance Fiber Reinforced Concrete (UHPFRC). The UHPFRC is a modern cementitious composite containing a large amount of cement, both reactive and nonreactive very fine particles, chemical admixtures and short high strength steel fibers. This type of concrete has superior durability and excellent mechanical properties. In this paper an UHPFRC containing 2% of fibers by volume with a compressive strength exceeding 150MPa is presented. In this study detailed descriptions of the measurements of compressive strength, bending strength, direct tensile strength, fracture energy and modulus of elasticity are given. The study provides a comparison of the above mentioned UHPFRC properties with high performance concrete, fiber reinforced concrete and conventional structural concrete. The results indicate excellent performance of UHPFRC in all categories. The biggest difference to ordinary concretes can be seen in tensile behavior, where its response in tension exhibits strain hardening accompanied with multiple cracking followed by tensile softening. The direct tensile strength of the studied material is 10MPa and its fracture energy is 5 times higher than that of conventional fiber reinforced concrete. It is believed, that such type of material is the future of concrete industry, it will allow executing higher, more effective structures with excellent durability. [Copyright &y& Elsevier]

Abstract: In this paper, the detailed experimental investigation was done to study the effect of partial replacement of cement by Fly Ash (FA) and Rice Husk Ash (RHA) in combine proportion started from 30% FA and 0% RHA mix together in concrete by replacement of cement with the gradual increase of RHA by 2.5% and simultaneously gradual decrease of FA by 2.5%. Last proportion was taken 15%FA and 15% RHA. The tests on hardened concrete were destructive in nature which includes compressive test on cube for size (150 x 150 x 150mm) at 7,14,28,56 and 90 days of curing as per IS: 516 — 1959, Flexural strength on beam (150 x 150 x700mm) at 28 days of curing as per IS: 516 1959 and split tensile strength on cylinder (150mm ø x 300mm) at 28 days of curing as per IS: 5816 1999. The work presented in this paper reports the effects on the behavior of concrete produced from cement with combination of FA and RHA at different proportions on the mechanical properties of concrete such as compressive strength, flexural strength, and split tensile strength. Investigation reported that compressive strength increases by 30.15% in compared with targeted strength and reduces by 8.73% compared with control concrete at 28 days, flexural strength increases by 4.57% compared with control concrete at 28 days, split tensile strength decreases by 9.58% compared with control concrete at 28 days, were obtained at combination of 22.5% FA and 7.5% RHA. Partial replacement of FA and RHA reduces the environmental effects, produces economical and eco-friendly concrete. [Copyright &y& Elsevier]

In this paper, some simple stress-strain relationships of the concrete material recommended in relevant Codes are appropriately simplified, then the damage factors of the simplified plastic damage constitutive model is determined based on Sidiroff’s energy equivalence principle. Mechanical characteristics of the concrete material under the simple tension or compression are analyzed by Finite element method. Through the comparison of numerical analysis results and Code constitutive relations, the damage factors of the simplified plastic damage constitutive model is verified. The unreinforced concrete beam static tests by Petersson is simulation analyzed by the nonlinear finite element method and plastic damage constitutive model. The effect of the unit size and the different linear softening constitutive relation on the analysis results are considered. The results show that there is no obvious size effect on the plastic damage analysis results based on fracture cracking criterion, the results of the bilinear softening constitutive analysis have good accuracy, and the form of softening constitutive relation has a great influence on the result. [ABSTRACT FROM AUTHOR]

An experiment was carried out to study the post-fire seismic performance of steel reinforced concrete (SRC) columns in this paper. Eight large-scale specimens were tested for their temperature distributions during the heating and cooling phase of a fire. Properties that define the post-fire seismic analysis of the SRC columns are studied with the test. The parameters include the heating time, the axial compression ratio and the steel ratio. It can be concluded from the study that the temperature increase in the inner core of the specimens shows significant delay compared to the outer perimeter and the fire temperature. A plastic hinge zone appears when the SRC column specimen is loaded to collapse after fire, and the length of the plastic hinge zone increases with the increase of heating time. The results show that in general the hysteresis loop shape is spindle-shaped except for a little pinch effect, which means the SRC column specimens have good energy dissipation capacity after fire. The stiffness of the specimens decreases with the increase of the heating time and the axial compression ratio. The stud and steel ratio have little influence on the stiffness. [ABSTRACT FROM AUTHOR]

This paper examines the impact responses of CFRP strengthened reinforced concrete (RC) beams through an experimental study. The experimental study involves a drop hammer impact test that investigates the influence of drop height, number of blows and CFRP strengthening scheme on its response. Four different types of CFRP strengthening schemes are applied to RC beams. This experimental study reveals that the RC beams strengthened with CFRP are significantly improved in the resistance to impact loadings. [ABSTRACT FROM AUTHOR]