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A novel design of a manhole kit holder, namely “Plakhor” was developed by TBBM Boyolali of PT Pertamina (Persero). The device has an advantage of a plug and play system which has an important feature to assist the cleaning of storage tank confined space. The present report addressed the design considerations, mechanical test results, and stress analysis of the developed device. The design was developed by considering engineering standards of API 650 while the stress analysis was conducted using finite element analysis (FEA). Meanwhile, a series of mechanical tests such as tensile strength, bending, press, and torsion were also conducted to determine the mechanical strength of the material used in this design. The stress analysis results indicated that the design construction was safe enough to hold the manhole weight and in an excellent agreement to that of the physical test result.

Nowadays, the process of metal forming in the industrial of welding and machinery is developing very rapidly, especially the bending process. In the manufacturing process, bending processes are often carried out to make and repair products such as electronic panel components, automobile vehicle panels, tool-boxes, burning fish, agricultural machinery and mechanization tools, etc. The complex-shaped bend parts with high precision are increasingly needed. To achieve high precision of parts, especially the bend angle, a suitable design of process parameters is strictly considered. An experimental study was conducted to determine the effect of punch parameters (i.e. punch radius and punch angle) on the bend angle in the V-bending process. Bending tests carried out several variable variations, including the punch angle (i.e. 85°, 87.5°, and 90°), and punch radius (i.e. 1 mm, 1.5 mm and 2 mm). The angle of 85° of die is constant. The analysis of variance (ANOVA) techniques was carried out to investigate the degree of significant process parameters in the air V-bending process. The results revealed that the degree of significant process parameters in air V-bending process depended on the punch angle. It can be concluded that the punch angle is significantly affected to the bend angle (less than 90° or more than 90°) while compared to the punch radius.

The suitability of forming operations for enhancing the mechanical properties and functionality of 3D-printed thermoplastic parts was studied and analyzed. Parts were made with fused filament fabrication 3D-printer. Materials used were common PLA and ABS plastics. Polymide CoPA (nylon 6/6,6) was also tested as one of the less used materials on this printer type. Different joints and geometries were made using thermoforming for 3D-printed plastic parts. Joint to metal was done using geometrical shape to lock it in place. Two hinges were made, one by directly 3D-printing and other by thermoforming 3D-printed parts. This allowed comparison between manufacturability, function and strength of the parts. A device was made to test utility and integrity of 3D-printed part through repeated heating and forming. Strength between directly 3D-printed geometry and formed geometry was also tested using a tensile test machine and three-point bending. Result showed that functionality and strength of the 3D-printed parts can be improved in some cases. Formability varied between materials and geometries. PLA benefitted most from thermoforming while Nylon had best improvement in strength. 3D-printed plastic can be thermoformed to further expand possibilities in manufacturing of AM parts.

Early-strength irrigated semi-flexible pavement (EISFP) is a new type of composition pavement with the characteristics of both asphalt pavement and cement concrete pavement. It has the advantages of high strength in the beginning and fast strength growth. EISPF-13 Marshall specimens with voids of 20%, 25% and 30% of base asphalt mixture were formed respectively. Rutting test, low temperature trabecular bending test and immersion Marshall test were used to evaluate the high temperature performance, low temperature performance and water damage resistance of EISPF-13 maintained for 3 hours and 28 days. The test results show that the pavement performance of EISPF-13 with 3-hour maintenance has reached more than 70% of that which have been maintained for 28 days. Moreover, the dynamic stability, residual stability of EISPF-13 maintained for 3-hour are better than SMA-13 asphalt mixture. Low temperature crack resistance of EISPF-13 is slightly poor, but it can still meet the technical requirements. Considering its comprehensive road performance, it is suggested that EISPF can be used for the road maintenance with high traffic pressure, because it can withstand traffic loads after 3-hour maintenance.

Lightweight design, lower fuel consumption and easier recyclability are the current concerns of the automotive industry as a response to the increasing demand for energy saving and better environmental impact of the transportation section. This framework was the opportunity to develop multi-layer materials, as an alternative to the high-density homogeneous metal sheets, maintaining the structural properties of the component. The multi-layer materials, known as composite sandwich or hybrid materials, are composed of outer metal sheets with reduced thickness and a polymeric matrix core (low density), in which high specific strengths are achieved. However, the lack of studies and information about the behavior of these non-homogeneous materials posed new challenges, either with regard to their use in the sheet metal forming processes, but also when performing material mechanical characterization. This paper presents the problems faced with bending test and springback analysis of a sandwich metal polymer sheet, compared with a high strength low alloy steel (HSLA420). Experimental tests and corresponding numerical simulations were performed using the press brake air bending process and a Numisheet benchmark test, unconstrained bending test, at room temperature, using the same experimental conditions for both materials. The numerical simulations were performed using finite element modeling. The results show that the sandwich material have problems on the structural integrity for a lower punch radius, on the outer surface (tension side). Additionally, the comparison of springback behavior showed that there is no significant difference between the materials in the study, although the non-homogeneous sandwich material presented a lower springback.

The bending limit or minimum bending radius of sheet metal is conventionally measured in a wiping (swing arm) or in a vee bend test and reported as the minimum radius of the tool over which the sheet can be bent without fracture. Frequently the material kinks while bending so that the actual inner bend radius of the sheet metal is smaller than the tool radius giving rise to inaccuracy in these methods. It has been shown in the previous studies that conventional bend test methods may under-estimate formability in bending dominated processes such as roll forming. A new test procedure is proposed here to improve understanding and measurement of fracture in bending and roll forming. In this study, conventional wiping test and vee bend test have been performed on martensitic steel to determine the minimum bend radius. In addition, the vee bend test is performed in an Erichsen sheet metal tester equipped with the GOM Aramis system to enable strain measurement on the outer surface during bending. The strain measurement before the onset of fracture is then used to determine the minimum bend radius. To compare this result with a technological process, a vee channel is roll formed and in-situ strain measurement carried out with the Vialux Autogrid system. The strain distribution at fracture in the roll forming process is compared with that predicted by the conventional bending tests and by the improved process. It is shown that for this forming operation and material, the improved procedure gives a more accurate prediction of fracture.

This paper compares the fatigue life of three different materials in the explosive welding process without and after heat treatment. For all cladding plates, the base material was P3335NH carbon steel about thickness of 10 mm, while super-duplex SAF2507 steel and austenitic 316L and 254SMO steels of 3 mm thickness were used as clad materials. As part of the work, ultrasonic testing were carried out to determine the cohesion of the materials joined. Next, heat treatment was applied and static tests were performed, including bend test, tensile test and shear test as well as impact strength test. Finally, fatigue tests were conducted, i.e. cyclic bending for four different load values. Static tests proved that when used with the heat treatment, the materials have deteriorated mechanical properties as compared to the tests with no heat treatment. Fatigue tests also show that fatigue life is significantly decreased after the heat treatment, except for the cladding in which super-duplex SAF2507 was used.

As a result of the increasing environmental awareness, the concern for environmental sustainability and the growing global waste problem, the interest of bio-composites materials is growing rapidly in the last years in order to use them in various engineering fields. Tremendous advantages and opportunities are associated with the use of these materials. On the other hand, some issues are related to the superficial properties of the bio-laminates, in particular the wear properties, the flame resistance and the aesthetic appearance have to be improved in order to extend the application fields of these materials. Aiming to these goals this paper deals with the study of the deposition of aluminum coating through cold spray process on hemp/PLA bio-composites manufactured by using the compression molding technique. Therefore, SEM observations, roughness analyses, bending tests, pin on disk and scratch tests were carried out in order to study the feasibility of the process and to investigate on the properties of the coated samples. The experimental results proved that when the process parameters of the deposition process are properly set, no damages are induced in the composite panel and that the aluminum coating, under specific load conditions, resulted to be able to protect the substrate.

Textile reinforced thermoplastic composites are predestined for highly automated medium- and high-volume production processes. The presented work focusses on experimental studies of different types of glass fibre reinforced polypropylene (GF-PP) semi-finished thermoplastic textiles to characterise the forming behaviour. The main deformation modes fabric shear, tension, thought-thickness compression and bending are investigated with special emphasis on the impact of the textile structure, the deformation temperature and rate dependency. The understanding of the fundamental forming behaviour is required to allow FEM based assessment and improvement of thermoforming process chains.Textile reinforced thermoplastic composites are predestined for highly automated medium- and high-volume production processes. The presented work focusses on experimental studies of different types of glass fibre reinforced polypropylene (GF-PP) semi-finished thermoplastic textiles to characterise the forming behaviour. The main deformation modes fabric shear, tension, thought-thickness compression and bending are investigated with special emphasis on the impact of the textile structure, the deformation temperature and rate dependency. The understanding of the fundamental forming behaviour is required to allow FEM based assessment and improvement of thermoforming process chains.

Since electric motors are gaining in importance in many fields of application, e.g. hybrid electric vehicles, optimization of the linear coil winding process greatly contributes to an increase in productivity and flexibility. For the investigation of the forming behavior of the winding wire the material behavior is characterized in different experimental setups. Numerical examinatons of the linear winding process are carried out in a case study for a rectangular bobbin in order to analyze the influence of forming parameters on the resulting properties of the wound coil. Besides the numerical investigation of the linear winding method by using the finite element method (FEM), a multi-body dynamics (MBD) simulation is carried out. The multi-body dynamics simulation is necessary to represent the movement of the bodies as well as the connection of the components during winding. The finite element method is used to represent the material behavior of the copper wire and the plastic strain distribution within the wire. It becomes clear that the MBD simulation is not sufficient for analyzing the process and the wire behavior in its entirety. Important parameters that define the final coil properties cannot be analyzed in the manner of a precise manifestation, e.g. the clearance between coil bobbin and wire as well as the wire deformation behavior in form of a diameter reduction which negatively affects the ohmic resistance. Finally, the numerical investigations are validated experimentally by linear winding tests.

As lightweight design as well as crash performance are crucial to future car body design, exact material characterisation is important to use materials at their full potential and reach maximum efficiency. Within the scope of this paper, the potential of newly established bending-tension test procedure to characterise material crashworthiness is investigated. In this test setup for the determination of material failure, a buckling-bending test is coupled with a subsequent tensile test. If prior bending load is critical, tensile strength and elongation in the subsequent tensile test are dramatically reduced. The new test procedure therefore offers an applicable definition of failure as the incapacity of energy consumption in subsequent phases of the crash represents failure of a component. In addition to that, the correlation of loading condition with actual crash scenarios (buckling and free bending) is improved compared to three- point bending test. The potential of newly established bending-tension test procedure to characterise material crashworthiness is investigated in this experimental studys on two aluminium sheet alloys. Experimental results are validated with existing ductility characterisation from edge compression test.As lightweight design as well as crash performance are crucial to future car body design, exact material characterisation is important to use materials at their full potential and reach maximum efficiency. Within the scope of this paper, the potential of newly established bending-tension test procedure to characterise material crashworthiness is investigated. In this test setup for the determination of material failure, a buckling-bending test is coupled with a subsequent tensile test. If prior bending load is critical, tensile strength and elongation in the subsequent tensile test are dramatically reduced. The new test procedure therefore offers an applicable definition of failure as the incapacity of energy consumption in subsequent phases of the crash represents failure of a component. In addition to that, the correlation of loading condition with actual crash scenarios (buckling and free bending) is improved compared to three- point bending test. The potential of newly established bending-tension test...

Ultra High Molecular Weight Polyethylene (UHMWPE) materials exhibit high impact strength, excellent abrasion resistance and high chemical resistance, making them attractive for a number of impact applications for automotive, marine and medical industries. One format of this class of materials that is being considered for the thermoforming process is a highly-oriented extruded thin film. Parts are made using a two-step manufacturing process that involves first producing a set of preforms and then consolidating these preforms into a final shaped part. To assist in the design of the processing parameters, simulations of the preforming and compression molding steps can be completed using the finite element method. Such simulations require material input data as developed through a comprehensive characterization test program, e.g. shear, tensile and bending, over the range of potential processing temperatures. The current research investigates the challenges associated with the characterization of thin, highly-oriented UHMWPE films. Variations in grip type, sample size and testing rates are explored to achieve convergence of the characterization data. Material characterization results are then used in finite element simulations of the tension test to explore element formulations that work well with the mechanical behavior. Comparisons of the results from the material characterization tests to results of simulations of the same test are performed to validate the finite element method parameters and the credibility of the user-defined material model.Ultra High Molecular Weight Polyethylene (UHMWPE) materials exhibit high impact strength, excellent abrasion resistance and high chemical resistance, making them attractive for a number of impact applications for automotive, marine and medical industries. One format of this class of materials that is being considered for the thermoforming process is a highly-oriented extruded thin film. Parts are made using a two-step manufacturing process that involves first producing a set of preforms and then consolidating these preforms into a final shaped part. To assist in the design of the processing parameters, simulations of the preforming and compression molding steps can be completed using the finite element method. Such simulations require material input data as developed through a comprehensive characterization test program, e.g. shear, tensile and bending, over the range of potential processing temperatures. The current research investigates the challenges associated with the characterization of thin, highly...

In this paper, the rotary type ultrasonic motor with bending spokes using radial mode, which can improve the output performance of ultrasonic motor and decrease the cost of manufacture, is presented. The proposed ultrasonic motor has good performance in the output torque and speed. The structure is simple and compact, so it has low dependence on the machining precision. The voltage to drive the motor is low and excitation method is simple. It is suitable for large-scale industrial application also due to its low production cost and reliable output. The current ultrasonic motor is designed for small size flying objects. Moreover, it can be used in miniature helicopter motors and micro-electronic equipment zoom systems such as capsule endoscope, electronic eyeball, SLR camera, smart phone, etc. The proposed motor has a wide application prospect in robot, medical device, micromechanical and aerospace science and technology field. Numerical simulations and experimental outcomes are given. The experimental investigation of the motor has confirmed the main results of numerical analysis and has given an opportunity to create high speed rotation.

Roll levelling is commonly used in cut to length and blanking lines to flatten initial coils and produce residual stress free precuts. Roll straightener is also used to remove coil-set when progressive dies are used and the starting raw material is a coil. Industrial evidences have proved that roll leveler or straightener tuning is crucial to get a robust process and to obtain repetitive springback values after stamping. This is more relevant when using Advanced High Strength Steels and aluminum coils. However, the mechanisms affecting this material behavior are unknown and how the levelling technology affects the material properties has not been yet reported.In this paper, the influence the roll levelling process has on the final properties of a 6xxx aluminum alloy is studied. For that, as received coils have been relevelled using two different leveler set-ups and tensile tests have been performed using both initial and final material states. Aiming to quantify the effect of the material hardening on a real forming process, a new tangential bending prototype has been developed. As received and levelled precuts have been bent and the forming torques and the postforming angles have been compared.

The applications of Advanced High-Strength Steels (AHSS) in the automotive industry are rapidly increasing due to a demand for a lightweight material that significantly reduces fuel consumption without compromising passenger safety. Automotive industries and material suppliers are expected by consumers to deliver reliable and affordable products, thus stimulating these manufacturers to research solutions to meet these customer requirements. The primary advantage of AHSS is its extremely high strength to weight ratio, an ideal material for the automotive industry. However, its low ductility is a major disadvantage, in particular, when using traditional cold forming processes such as roll forming and deep drawing process to form profiles. Consequently, AHSS parts frequently fail to form. Thereby, in order to improve quality and reliability on manufacturing AHSS products, a recently-developed incremental cold sheet metal forming technology called Chain-die Forming (CDF) is recognised as a potential solution to the forming process of AHSS. The typical CDF process is a combination of bending and roll forming processes which is equivalent to a roll with a large deforming radius, and incrementally forms the desired shape with split die and segments. This study focuses on manufacturing an AHSS top-hat section with minimum passes without geometrical or surface defects by using finite element modelling and simulations. The developed numerical simulation is employed to investigate the influences on the main control parameter of the CDF process while forming AHSS products and further develop new die-punch sets of compensation design via a numerical optimal process. In addition, the study focuses on the tool design to compensate spring-back and reduce friction between tooling and sheet-metal. This reduces the number of passes, thereby improving productivity and reducing energy consumption and material waste. This numerical study reveals that CDF forms AHSS products of complex profiles with much less residual stress, low spring back, low strain and of higher geometrical accuracy compared to other traditional manufacturing processes.

Aircraft structures are exposed to many loads during their working lifespan. Every particular action made during a flight is composed of a series of air movements which generate various aircraft loads. The most rigorous requirement which modern aircraft structures must fulfill is to maintain their high durability and reliability. This requirement involves taking many restrictions into account during the aircraft design process. The most important factor is the structure’s overall mass, which has a crucial impact on both utility properties and cost-effectiveness. This makes aircraft one of the most complex results of modern technology. Additionally, there is currently an increasing utilization of high strength aluminum alloys, which requires the implementation of new manufacturing processes. High Speed Machining technology (HSM) is currently one of the most important machining technologies used in the aviation industry, especially in the machining of aluminium alloys. The primary difference between HSM and other milling techniques is the ability to select cutting parameters – depth of the cut layer, feed rate, and cutting speed in order to simultaneously ensure high quality, precision of the machined surface, and high machining efficiency, all of which shorten the manufacturing process of the integral components. In this paper, the authors explain the implementation of the HSM method in integral aircraft constructions. It presents the method of the airframe manufacturing method, and the final results. The HSM method is compared to the previous method where all subcomponents were manufactured by bending and forming processes, and then, they were joined by riveting.Aircraft structures are exposed to many loads during their working lifespan. Every particular action made during a flight is composed of a series of air movements which generate various aircraft loads. The most rigorous requirement which modern aircraft structures must fulfill is to maintain their high durability and reliability. This requirement involves taking many restrictions into account during the aircraft design process. The most important factor is the structure’s overall mass, which has a crucial impact on both utility properties and cost-effectiveness. This makes aircraft one of the most complex results of modern technology. Additionally, there is currently an increasing utilization of high strength aluminum alloys, which requires the implementation of new manufacturing processes. High Speed Machining technology (HSM) is currently one of the most important machining technologies used in the aviation industry, especially in the machining of aluminium alloys. The primary difference between HSM and...

Today, in the automotive industry dual phase (DP) steels are extensively used in the production of various structural parts due to their superior mechanical properties. Hole-flanging of such steels due to simultaneous bending and stretching of sheet metal, is complex and associated with some issues such as strain and strain rate localization, development of micro-cracks, inhomogeneous sheet thinning, etc. In this study an attempt is made to improve the formability of DP sheets, by localized Laser heating. The Laser beam was oscillated in circular pattern rapidly around the pre-hole, blanked prior to the flanging process. In order to investigate formability of DP steel (DP1000), several uniaxial tensile tests were conducted from quasi to intermediate strain rates at different temperatures in warm regime. Additionally, experimentally acquired temperature and strain rate-dependent flow curves were fed into thermomechanical finite element (FE) simulation of the hole-flanging process using the commercial FE software ABAQUS/Explicit. Several FE simulations were performed in order to evaluate the effect of blank’s initial temperature and punch speed on deformation localization, stress evolution and temperature distribution in DP1000 sheets during warm hole-flanging process. The experimental and numerical analyses revealed that prescribing a distribution of initial temperature between 300 to 400 °C to the blank and setting a punch speed that accommodates strain rate range of 1 to 5 s-1 in the blank, provides the highest strain hardening capacity in the considered rate and temperature regimes for DP1000. This is in fact largely due to the dynamic strain aging (DSA) effect which occurs due to pinning of mobile dislocations by interstitial solute atoms, particularly at elevated temperatures.

Seamless pipe elbows are important components in mechanical, plant and apparatus engineering. Typically, they are produced by the so-called ‘Hamburg process’. In this hot forming process, the initial pipes are subsequently pushed over an ox-horn-shaped bending mandrel. The geometric shape of the mandrel influences the diameter, bending radius and wall thickness distribution of the pipe elbow. This paper presents the numerical simulation model of the hot mandrel bending process created to ensure that the optimum mandrel geometry can be determined at an early stage. A fundamental analysis was conducted to determine the influence of significant parameters on the pipe elbow quality. The chosen methods and approach as well as the corresponding results are described in this paper.

Sandwich panels are readily used in civil engineering due to their high strength to weight ratio and the ease and speed of assembly. The idea of a sandwich section is to combine thin and durable facings with a light-weight core and the choice of materials used allows obtaining the desired behaviour. Panels in consideration consist of MgO (magnesium oxide) board facings and expanded polystyrene core and are characterized by immunity to biological corrosion, a high thermal insulation and a relatively low impact on environment. Customizing the range of panels to meet market needs requires frequent size changes, leading to different failure modes, which are identified in a series of costly full-scale laboratory tests. A nonlinear numerical model was created with a use of a commercial ABAQUS code and a user-defined procedure, which is able to reproduce observed failure mechanisms; its parameters were established on the basis of small-scale tests and numerical experiments. The model was validated by a comparison with the results of the full-scale bending and compression tests. The results obtained were in satisfactory agreement with the test data.

Rapid Prototyping (RP) technologies, the manufacturing technology with less time consuming including high precission and complicated structure of products, are now become high demanding technologies. Those technologies can be base on top-down or bottom-up approaches. One of the bottom-up approach of RP technology is 3D printing machine. In this research, we have succeed to apply the droplet-based 3D printer to make the structured PLA (Polylactic Acid) materials with different internal geometry structures. The internal geometry used are triangle and honeycomb structure with different size of each symmetry axis of 4.5 mm and 9 mm and the thickness varied of 1 mm and 2 mm as well. The mechanical properties of those structures including tensile and bending stregth are evaluated by using tensile and flexural test respectively. Test results show that the best performance obtained by measuring its tensile and flexural strength is the sampel with triangle geometry of 9 mm geometrical size and 2 mm of thickness. T...

A typical steel rebar can be bend using traditional bending machines without much of a problem. Glass Fiber Reinforced Polymer (GFRP) rebar possesses very less tensile strength, being thermoset in nature, will break easily and so cannot be bend on site. The present work addressed the problem of producing GPR rebar with the same materials used in standard pultrusion but, by modifying the process, with the possibility to bend them. The results showed bending is possible when accurate cure control is made.

There is risk of bridge foundations to be damaged by liquefaction-induced lateral spreading of ground. Once bridge foundations have been damaged, it takes a lot of time for restoration. Therefore, it is important to assess the seismic behavior of the foundations on liquefiable ground appropriately. In this study, shaking table tests of models on a scale of 1/10 were conducted at the large scale shaking table in Public Works Research Institute, Japan, to investigate the seismic behavior of pile-supported bridge abutment on liquefiable ground. The shaking table tests were conducted for three types of model. Two are models of existing bridge which was built without design for liquefaction and the other is a model of bridge which was designed based on the current Japanese design specifications for highway bridges. As a result, the bending strains of piles of the abutment which were designed based on the current design specifications were less than those of the existing bridge.

The objective of this research is to study the effect of the holding times of pack carburizing process on fatigue characteristic of v-notch shaft steel specimens. The carbon source was taken from charcoal of unused mahogany. The holding times were 2, 3 and 4 hours. The fatigue tests were conducted on rotary bending machine. The specimens were made of low carbon steel of 0.17% carbon content. Pack carburizing was conducted to the specimens at 930°C. V-notch was made to present the stress concentration on the specimens. To see the effects of the carburizing in changing the material properties, the micro-structures and hardness tests along the cross sectional area of the specimens were carried out. The results showed that the holding time of the carburizing process influences the fatigue strength of the material. The longer the holding time will be the higher the fatigue strength. The increase of the fatigue strength is due to the carbon content on the surface. It was confirmed by the micro-structures and th...

Simple Structural Surfaces (SSS) method is offered as a means of organizing the process for rationalizing the basic vehicle body structure load paths. The application of this simplified approach is highly beneficial in the development of modern passenger car structure design. In Malaysia, the SSS topic has been widely adopted and seems compulsory in various automotive programs related to automotive vehicle structures in many higher education institutions. However, there is no real physical model of SSS available to gain considerable insight and understanding into the function of each major subassembly in the whole vehicle structures. Based on this motivation, a real physical SSS of sedan model and the corresponding model vehicle tests of bending is proposed in this work. The proposed approach is relatively easy to understand as compared to Finite Element Method (FEM). The results prove that the proposed vehicle model test is useful to physically demonstrate the importance of providing continuous load path using the necessary structural components within the vehicle structures. It is clearly observed that the global bending stiffness reduce significantly when more panels are removed from the complete SSS model. The analysis shows the front parcel shelf is an important subassembly to sustain bending load.

A linear optimization method is applied to improve mechanical properties of fiber reinforced cement mortar. Since this method is preferably used in other scientific disciplines, few preconditions are taken into account in advance, in order to accommodate it to the specifics related to building materials design. Defining physical limitations and accelerating the optimization process, the target values of optimization are reached in 21 days after 3 optimization steps. Within this relatively short time span, the compressive and bending strengths of fiber reinforced cement mortar increase from 36.9 to 52.2 MPa and from 9.1 to 10.1 MPa, respectively, while identical components are used. The improvements are achieved after preparation of only nine different mixtures, which is a very small number confirming the effectivity of this method in the field of building materials design.

Electrical cable is a whole of the material including metal (cooper) conductor and its insulation, when an electrical cable is flowed by electric current, based on its own capacity, the temperature of cable conductor increases gradually. If the current flows above the cable carrying capacity, then an extreme temperature rises are expected. When temperature increase, the electric current flow inside cable conductor will decrease gradually related to the resistance and could occur repeatedly in a period. Since electrical faults on electrical cable system are often suspected as the cause of fires, thus this research aims to investigate measures of preventing the fire to start by means of controlling oxygen concentration in a cable compartment. The experimental work was conducted in laboratory by using electrical power cable of 1.5 mm2 size. Two transparent chambers were applied for studying the effect of vertical and horizontal orientations on the cable temperature rise, under various oxygen concentration of...

A special bend test has been developed and applied for the purpose of characterization and comparison of the material ductility in crankpin steel discs manufactured by casting, or casting subsequently followed by hot open-die forging (ODF) or closed-die forging (CDF). The bending test specimen consists of a small rectangular plate of material with a round hole cut out in the middle. The “eye-shape” specimens were cut out from various positions either near to the surface of, or from the interior of the discs. The test method revealed differences in ductility for the investigated materials, and for different depth positions inside the discs. The roughening of the specimen surface on the top-side of the specimen bend also varied dependent on the processing method for the material. Current results show that this test method is useful for evaluation of material quality in differently processed material. Experimental bend test results are presented for differently processed variants of the same material, i.e., ...

While weight has been so far the main driver for the development of prepreg based-composites solutions for aeronautics, a new weight-cost trade-off tends to drive choices for next-generation aircrafts. As a response, Hexcel has designed a new dry reinforcement type for aircraft primary structures, which combines the benefits of automation, out-of-autoclave process cost-effectiveness, and mechanical performances competitive to prepreg solutions: HiTape® is a unidirectional (UD) dry carbon reinforcement with thermoplastic veil on each side designed for aircraft primary structures [1-3]. One privileged process route for HiTape® in high volume automated processes consists in forming initially flat dry reinforcement stacks, before resin infusion [4] or injection. Simulation of the forming step aims at predicting the geometry and mechanical properties of the formed stack (so-called preform) for process optimisation. Extensive work has been carried out on prepreg and dry woven fabrics forming behaviour and simulation, but the interest for dry non-woven reinforcements has emerged more recently. Some work has been achieved on non crimp fabrics but studies on the forming behaviour of UDs are seldom and deal with UD prepregs only.Tension and bending in the fibre direction, along with inter-ply friction have been identified as the main mechanisms controlling the HiTape® response during forming. Bending has been characterised using a modified Peirce’s flexometer [5] and inter-ply friction study is under development. Anisotropic hyperelastic constitutive models have been selected to represent the assumed decoupled deformation mechanisms. Model parameters are then identified from associated experimental results. For forming simulation, a continuous approach at the macroscopic scale has been selected first, and simulation is carried out in the Zset framework [6] using proper shell finite elements.

There has been a high demand for weight reduction in automotive vehicles while maintaining passenger safety. A potential steel material to achieve this is Ultra High Strength Steel (UHSS). As a high strength material, it is difficult to be formed with desired profiles using traditional sheet metal forming processes such as Cold Roll Forming. To overcome this problem, a potentially alternative solution is Chain-die Forming (CDF), recently developed. The basic principal of the CDF is to fully combine roll forming and bending processes. The main advantage of this process is the elongated deformation length that significantly increases effective roll radius. This study focuses on identifying issues with the CDF by using CAD modelling, Motion Analysis and Finite Element Analysis (FEA) to devise solutions and construct a more reliable process in an optimal design sense. Some attempts on finite element modelling and simulation of the CDF were conducted using relatively simple models in literature and the researc...

Advancing requirements and decreasing tolerances for the mechanical properties of heavy steel plates, especially the yield strength and the tensile strength, necessitate sound knowledge of the influence of all consecutive process steps. In this work the focus is taken on the leveling process. The present paper represents a combined methodology to characterize the tensile properties with experimental as well as numerical simulation techniques. An four-point bending test rig has been designed which enables the cyclic testing of plate like samples up to 40 mm thickness applying typical strain histories of the leveling operation. Small-scale tensile specimens with rectangular cross section are taken across the entire plate thickness to characterize the change of the local tensile behavior from the un-deformed to the deformed state. The bending experiments are reproduced by finite element simulations. The implemented material model has been calibrated on the basis of uniaxial cyclic tension/compression tests. ...

AA6111 is a commonly used aluminum alloy for body-in-white (BIW) components with good bake-hardening response, high strength and excellent formability. For industrial applications various process strategies are considered to reach strength of about 250 MPa in the final body part with that type of alloy. The purpose of this paper is to discuss recent process strategies of high-strength AA6111 sheets to evaluate the forming characteristics, precipitation kinetics dissolution and mechanical properties in the final condition. The forming behavior is investigated by four potential process chains after single-stage or multi-stage heat treatment including T4 (pre-aged at > 80 °C after quenching), T61 (T4 + artificial aged at 120-150 °C for 10-18 h), T6 (T4 + artificial aged at 180-220°C up to 12 h) and PFHT (T4 + post form heat treatment at 205°C for 30 min). The experimental input for characterization of the formability consists of tensile tests, bending tests and drawing tests. Differential Scanning Calorimetr...

Roll forming is a manufacturing process, whose profitability is predicated on its high output. When roll formed profiles are cut to length, process related residual stresses are released and increased deformation at the profile ends at the cut-off occurs, also known as end flare. U-profiles typically show a flaring in at the lead end and a flaring out at the tail end. Due to this deformation, deviations from the dimensional accuracy can occur, which cause problems during further processing of the parts. Additional operations are necessary to compensate for the end flare, thereby increasing plant deployment time and production costs. Recent research focused on the cause of the residual stresses and it was shown, that a combination of residual longitudinal stresses and residual shear stresses are responsible for end flare. By exploiting this knowledge, it is possible to determine, depending on the flaring of the profile, in which part of the profile residual longitudinal or residual shear stresses are prevalent and which counter measures can specifically counteract the responsible residual stresses. For this purpose numerical and experimental investigations on a U-, Hat- and C-Profile were conducted. It could be shown that overbending and bending back of the profile is most effective in reducing end flare. Another developed method is lowering and elevating the profile to reduce residual longitudinal stresses.

Lab-scaled AA7075 aluminum side impact beams were manufactured using the die quenching technique in which the sheet was solutionized and then quenched in-die during forming to a super saturated solid state. Sheet thinning measurements were taken at various locations throughout the length of the part and the effect of lubricant on surface scoring and material pick-up on the die was evaluated. The as-formed beams were subjected to a T6 aging treatment and then tested in three-point bending. Simulations were performed of the forming and mechanical testing experiments using the LS-DYNA finite element code. The thinning and mechanical response was predicted well.

The hot forming of thermoset prepreg consists in bending an uncured composite part by applying a mechanical constrain on the hot laminate. Most of the time, the mold is inserted in a vacuum box and the mechanical constrain is applied on the composite laminate by a single membrane or a double-membrane. But the performance improvement products resulted in forming increasingly complex parts with advanced materials having a less formability. These new complex parts require a finer comprehension of the process and an optimization of the key parameters to get acceptable quality. In this work, an experimental study has been carried out to identify the process conditions that do not lead to unacceptable defaults: undulations of fibers. In the present study, downward-bending has been evaluated with an original light mechanical forming concept, for a given stacking sequence. The influence of the part’s temperature and the part’s bending speed are investigated. To carry this study out, a hot forming test bench has been designed and manufactured to have a precise supervision of the process conditions. It is able to bend parts of 1500 mm length x 600 mm width x 20 mm thick.

Tool steels are considered as hard to deform materials since they have a mixture of soft ferritic matrix with hard carbides as secondary particles. In this study, 5 mm thick plates of AISI A8-Modified tool steel were subjected to cold rolling prior to the quench-temper cycle with the view to investigate the work hardening behavior of this steel during rolling and to reduce the brittleness of the product after the quench-temper cycle. 5mm thick samples were rolled 10, 20, 30, 40, and 50 (%) under similar conditions and then cut parallel to the rolling direction. Microstructure evolution, deformation-induced microvoids, and hardness evolution as a function of prior deformation were investigated. Electron microscopy was used to investigate the root causes for the formation of microvoids and potential alligatoring failure. The influence of microvoids on mechanical properties after the quench-temper cycle was evaluated through bending tests. Results showed no failure for 50% cold rolled sample in comparison wi...

Research of various textile materials in technical application has been done numerously within the past few decades. Woven fabric is one of the textile material that have shown a prominent mechanical properties toward the technical application requirements. Application such in structure reinforcement requires good mechanical performance capabilities particularly in tensile, fracture tolerance, impact and bending resistance. This paper presents a comprehensive experimental study on the influence of weft density towards the yarn crimp and mechanical tensile strength behaviour of 3D Angle Interlock woven fabric. The woven fabric sample was fabricated into four different weft densities; 12, 16, 20 and 24 picks per cm by using polyester plied yarn with 100 Tex. Tensile strength sample was tested accordingly based on the ASTM standard. Results presented shows the increases value of weft density will improve the tensile strength performance.

In accordance to the increasing demands in profile manufacturing the general profile geometries become more and more complex. The complexity is basically characterized by varying cross section geometry along the profile axis as well as a longitudinal curvature. A new process for the flexible manufacturing of curved profiles with variable cross section geometries along the longitudinal axis is introduced. The process is a combination of the incremental profile forming process and a free form bending operation and has a high potential for lightweight construction and energy saving. Beside the description of the process principle and possible machine setups, the potentials of the process are discussed in this article.

We introduce a new cloth simulation algorithm that uses a special data of nodes-springs-elements (NSE) order that able to achieve to a realistic cloth simulation. We develop ordering procedures on data of spring-mass system that represents physics and geometrics of a cloth as in reality. In our experiments, we developed a rectangle cloth model which is initially at a horizontal position with one fixed point and it is allowed to drape by its own weight. Our simulation result is not only able to achieve a plausible cloth drapes but also reduce overstretching when large time step is used. This paper aims to demonstrate the reliability of our approach to eliminate overstretching and ability to control bending properties during simulation.

In the development of ship structures applying new materials and it’s purposeful placement play an important role. During the last years, especially in a construction of ro-ro type vessels, the usage of novel sandwich structures in cargo decks is profitable. Steel sandwich panel is an innovative solution which at a todays state of development can be used for the construction of any members not taking part in a global bending of a hull. The one important reason for this is a lack of knowledge and experience in the fatigue assessment. The problem of fatigue assessment of the steel sandwich structures arises from no typical welds connecting its structural components. The joints are fabricated by the use of laser welding technique, or hybrid welding. Standard methodology for the fatigue analysis is local stress approach or local strain approach. In both methods the crucial aspect is determination of a maximum values of strains and stresses. The most effective technique to designate these values is numerical modelling with the use of Finite Element Method or Boundary Element Method. In this paper the comparison of local stresses at a weld notch obtained by two independent methods is presented. The results calculated by the Finite Element Analysis are being compared with the experimental one measured by the use of laser extensometer grid technique. The goal of this comparison is verification of the main numerical modelling assumptions.

Sebelas Maret University has been developing an Electric Vehicle namely SmarT-EV UNS. The main structure of the car are chasis and body. The chasis is made from steel and the body is made from fiberglass composite. To ensure the safety of the car, both static and dynamic tests were carried out to these structures, including their materials, like: tensile test, bending test, and impact test. Another test needed by this vehicle is crashworthiness test. To perform the test, it is needed complex equipments and it is quite expensive. Another way to obtain vehicle crashworthiness behaviour is by simulate it. The purpose of this study was to simulate the response of the Smart-EV UNS electric vehicle main structure when crashing rigid barrier from the front. The crash simulation was done in according to the NHTSA (National Highway Traffic Safety Administration) within the speed of the vehicle of 35 mph. The UNS Electric Vehicle was modelled using SolidWorks software, and the simulation process was done by finite element method using ANSYS software. The simulation result showed that the most internal impact energy was absorbed by chassis part. It absorbed 76.2% of impact energy, then the base absorbed 11.3 %, while the front body absorbed 2.5 %, and the rest was absorbed by fender, hood, and other parts.

This paper presents the results of fatigue tests carried out for specimens made of S355 steel under bending block loading with the mean value of loading. The tests consisted in increasing and decreasing the mean value of loading in subsequent blocks. Experimental tests show a significant difference in the fatigue life of the material depending on whether the mean value of loading is increased or decreased in the next sequences of the loading block. Models taking into account the influence of mean loading on the fatigue life calculated by means algorithms were verified. It was shown that computational models based on the SWT parameter appropriately describe the results of the experiment; however, when introducing the coefficient of the material sensitivity to the stress ratio, its change together with the number of cycles to failure should be taken into account.

Multiroll leveling is a forming process used in the metals industries (aluminum, steel, …) in order to correct flatness defects and minimize residual stresses in strips thanks to alternating bending. This work proposes a Finite Element 2D model to simulate the metal sheet conveying through the machine. Obtained results (plastic strain and residual stress distributions through thickness) are analysed. Strip deformation, after elastic springback and potential buckling, is also predicted (residual curvatures).

Pre-stress shot peen forming is an effective plastic forming method for integral panels with stiffeners used in aeronautical industry. 7050 aluminum alloy panels with stiffeners were pre-stress peen formed in an orthogonal experiment. The deformation rule of those workpieces whose exterior surfaces were convex bending was investigated. The results show that the contribution of peening parameters on workpiece deformation is in following order: air pressure, pre-load stress and moving velocity of workpiece. The deformation of workpiece whose merely exterior surface is peened is much lower than that whose two side-faces of stiffener are also peened. The decreasing rate is changed from 13% to 39% by means of parameters variation. Moreover, the regression formulas about the quantitative relationships between radius of curvature and peening parameters have been established. The results could offer some basic reference to peen forming aluminum alloy panels of future aircrafts.

The article addresses results of tests of performance characteristics of a tube bend made of the 15NiCuMoNb5-6-4 steel, the latter being for manufacture of feed water pipelines used in power engineering systems. The tube bend was developed by bending with local induction heating, and the optimum tube bending parameters were established based on numerical simulations of the bending process. The mechanical properties of the tube bend were attained through quenching and tempering. Tests of mechanical properties were conducted using samples collected at different zones of the tube bend (the straight one as well as those subject to tension and compression), and compared with properties of the as-delivered tube material. The established basic mechanical properties of the tube bend, required under the applicable standards, were supplemented with results of low-cycle fatigue and creep tests, the purpose of which was to acquire information on the tube bend material service life under conditions of steady and unste...

In this study, the equivalent material properties in the extruded aluminum panel were verified and used to predict the behavior of the car body of urban railway vehicles. Firstly, the four equivalent material properties proposed by Cote were examined through the comparisons with FE results. And then, three-point bending test on the aluminum panel was also simulated using homogenized core models having the equivalent properties. For more details, a model with additional ribs was simulated as well. Finally, a railway vehicle car body with equivalent properties was analyzed under a vertical load in comparison with corrugated core model (namely initial model). Consequently, the results were in good agreement with the FE simulations of the initial model. Other load cases also will be carried out at a future work.

Additive production techniques have the advantage of manufacturing parts without needing a forming tool. One of the most used additive manufacturing processes is "Fused Deposition Modeling" (FDM) which allows the production of prototypes and end-use parts. Due to the manufacture layer by layer, also complex part geometries can be created in one working step. Furthermore, lightweight parts with specific inner core structures can be manufactured in order to achieve good weightrelated strength properties. In this paper the mechanical behavior of lightweight parts manufactured with the 3D production system Fortus 400mc from Stratasys and the material Polyetherimide (PEI) with the trade name Ultem*9085 is analyzed. The test specimens were built up with different inner structures and building directions. Therefore, test specimens with known lightweight core geometries (e.g. corrugated and honeycomb cores) were designed. A four-point bending test was conducted to analyze the strength properties as well as the weight-related strength properties. Additionally the influence of the structure width, the structure wall thickness and the top layer thickness was analyzed using a honeycomb structure.

Recently, there is a trend to apply the piping bended by induction heating process to nuclear power plants. Residual stress can be generated due to thermo-mechanical mechanism during the induction heating bending process. It is well-known that the residual stress has important effect on crack initiation and growth. The previous studies have focused on the thickness variation. In part, some studies were performed for residual stress evaluation of the austenitic stainless steel piping bended by induction heating. It is difficult to find the residual stresses of the ferritic steel piping bended by the induction heating. The study assessed the residual stresses of induction heating bended ferriticsteel piping via finite element analysis. As a result, it was identified that high residual stresses are generated on local outersurface region of the induction heating bended ferritic piping.

Thermoplastic foam injection molding (FIM) in combination with insert molding (IM) offers a possibility to generate sandwich panels in a one-step process. The prepared face sheets are first positioned inside the mold. A preheating process is carried out using quartz infrared emitters, which are mounted on a linear robot, before the mold is closed. The injection of the gas/melt mixture is combined with an embossing of the mold to further improve the face-core-adhesion. Finally, to initiate the foaming process, adjust the extent of foaming of the core and achieve the desired component dimensions, a mold opening stroke is carried out. The process described was performed with different facing materials, layer dimensions and overall wall thicknesses. Drawn PP fabrics (Curv®) as well as PP/GF70 tapes and consolidated sheets (unidirectional) were used to generate sandwich panels in a range of 5 to 6.4 mm thickness. PP was also chosen to form the foamed core which, in combination with the Curv® face sheets, produces a fully recyclable self-reinforced polymer (SRP) composite. Detailed process descriptions and the results of bending tests demonstrate the high potential. Other focuses are the preheating process and the foam structure.

Surfaces of technical parts are getting more and more attention in terms of functionalization. By modification, additional functionality is given to the part, e.g. self-cleaning effect or antireflection behavior. Nowadays mainly flat surfaces are structured which is a consequence of the available production methods. However, the demand of micro structured free form surfaces is increasing, enabling novel products. A major problem in the mass production (e.g. injection molding) of structured freeform surfaces is to demold these structures without ripping or deforming them due to occurring undercuts. Recently a novel concept was developed which overcomes this limitation. A nickel substrate containing a structure composed of lines orientated in two different directions, one orientated in melt flow direction, the other one perpendicular to that, but both with a cross-section of approximately 45 μm × 55 μm (w × h) was used as a premaster to cast a flexible master. This master made of poly(dimethylsiloxane) (PDMS) was mounted on a bending edge in an injection mold cavity. Within this paper the influence of process parameters on the replication grade of the structure lines depending on the structure orientation was evaluated, varying the holding pressure, melt and mold temperature using statistical design of experiment methods. The replication grade was evaluated by characterizing the shape of the structure lines along the entire process chain, using an infinite focus system. The results show, that the melt temperature has the biggest influence on the dimensions of the structures, the mold temperature only a slight one.

Roll forming is a continuous process in which a flat strip is shaped to the desired profile by sequential bending in a series of roll stands. Because of the large variety of applications of roll forming in the industry, Finite Element Analysis (FEA) is increasingly utilized for roll forming process design. Bending is the dominant deformation mode in roll forming. Sheet materials used in this process are generally temper rolled, roller- or tension- leveled. These processes introduce residual stresses into the material, and recent studies have shown that those affect the material behavior in bending. In this study a numerical model of the temper rolling (skin passing) process was used to determine a residual stress distribution in a dual phase, DP780, steel strip. A 5-stand roll forming process for the forming of a V-section was modeled, and the effect of various thickness reduction levels in the temper rolling process on the final shape defects was analyzed. The results show that a small thickness reduction in the temper rolling process decreases the maximum bow height but the final springback angle increases. It is also shown that reasonable model accuracy can be achieved by including the residual stress information due to temper rolling as initial condition in the numerical modeling of a roll forming process.