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The Bonded repair is broadly used in aging aircrafts to improve the structural integrity of damaged aircraft panels. The aim of this paper is to study the behaviour of multiple cracks on the flat panels using FEA. In this paper two twin collinear cracks are modeled and analyzed in terms of stress intensity factor(SIF). To improve the strength of the panel with multiple cracks it is repaired by adhesively bonded composite patch. It is shown that bonded repair reduces SIF near the crack tips of multiple cracks. Further, the adhesive is the weakest link which undergo failure under the applied load. Hence in this work debonding analysis of patch from the panel is carried out by appling load in increments. From the debonding analysis it is observed that the debonding of patch reduces the strength of repaired panel and leads to rise in SIF at the crack tips.The Bonded repair is broadly used in aging aircrafts to improve the structural integrity of damaged aircraft panels. The aim of this paper is to study the behaviour of multiple cracks on the flat panels using FEA. In this paper two twin collinear cracks are modeled and analyzed in terms of stress intensity factor(SIF). To improve the strength of the panel with multiple cracks it is repaired by adhesively bonded composite patch. It is shown that bonded repair reduces SIF near the crack tips of multiple cracks. Further, the adhesive is the weakest link which undergo failure under the applied load. Hence in this work debonding analysis of patch from the panel is carried out by appling load in increments. From the debonding analysis it is observed that the debonding of patch reduces the strength of repaired panel and leads to rise in SIF at the crack tips.

Composite materials are unendingly growing greater centrality in the field of engineering. In this paper, we have focused mainly on hybrid fiber reinforced polymer composite materials as a pipe. This work concentrates on the hybrid (Aramid and Glass) fiber as a reinforcement of the epoxy matrix. The advantage of hybridization is to increase the strength of compression. The aim of paper is to study the effect of compression of hybrid fiber pipe after seawater immersion for 30, 60 and 90 days. We describe a method for making a lightweight, energy absorbing, glass fiber reinforced aramid fiber, Aramid fiber reinforced glass fiber composite pipe and explore through effect of compressive response was analyzed. The experimental compression value was validated in the FEA analysis.

Femur bone stress shielding is known to be a significant factor in aseptic loosening or failure of hip replacements. This paper considers the development of a porous stemmed hip implant for children patient in order to reduce the effects of stress shielding and also maintaining acceptably low levels of stress in other areas of prosthesis. By using finite element modeling, the stresses in the proximal femur using porous stem were calculated and analyzed. The developed model is considered safe in terms of mechanical strength. The porous region does not bring significant effect on stress distribution but produces a considerable amount of compressive strain.Femur bone stress shielding is known to be a significant factor in aseptic loosening or failure of hip replacements. This paper considers the development of a porous stemmed hip implant for children patient in order to reduce the effects of stress shielding and also maintaining acceptably low levels of stress in other areas of prosthesis. By using finite element modeling, the stresses in the proximal femur using porous stem were calculated and analyzed. The developed model is considered safe in terms of mechanical strength. The porous region does not bring significant effect on stress distribution but produces a considerable amount of compressive strain.

This paper deals with the determination of the dynamic stress intensity factor (DSIF) for two locations of a crack in the beam with L-shaped cross section. The cracks pass through the entire profile body thickness in both position cases.The results shown below were obtained by 3D finite element analysis. Considering only static load (axial tensile) on a beam under given boundary conditions, the SIF for modes II and III was negligible compared to the SIF for mode I. In the case of impulse loading, the mixed mode of loading was introduced due to reflective stress waves.In the first step of analysis, the static SIF was determined for given cracked body geometries. Subsequently, the natural frequencies and their respective ratio of effective to total mass were calculated by modal analysis. After identifying the dominant natural frequency at which the beam oscillates in the direction of the longitudinal axis was done, the duration of time step required for transient analysis was determined.The analysis results are the time record of the SIF for all three loading modes of crack. The results of tensile and compressive impulse forces in the form of half-wave function sine are compared. Overall, six cases are evaluated depending on the position of the crack and the applied external load.This paper deals with the determination of the dynamic stress intensity factor (DSIF) for two locations of a crack in the beam with L-shaped cross section. The cracks pass through the entire profile body thickness in both position cases.The results shown below were obtained by 3D finite element analysis. Considering only static load (axial tensile) on a beam under given boundary conditions, the SIF for modes II and III was negligible compared to the SIF for mode I. In the case of impulse loading, the mixed mode of loading was introduced due to reflective stress waves.In the first step of analysis, the static SIF was determined for given cracked body geometries. Subsequently, the natural frequencies and their respective ratio of effective to total mass were calculated by modal analysis. After identifying the dominant natural frequency at which the beam oscillates in the direction of the longitudinal axis was done, the duration of time step required for transient analysis was determined.The analysis results...

This paper concentrates on selected aspects of numerical modeling of a short span thin-walled beams. The performed numerical simulations cover different types of finite elements (shell or solid finite elements) and different mesh sizes. Moreover the shape and magnitude of an initial geometrical imperfection is also investigated. The numerical analysis were made with the Newton-Raphson procedure with geometrical and material nonlinearity. The numerical results were compared with the laboratory four point bending test of a thin-walled beam. Furthermore, some guidelines for numerical simulations of a short span thin-walled beams in bending were proposed by authors.This paper concentrates on selected aspects of numerical modeling of a short span thin-walled beams. The performed numerical simulations cover different types of finite elements (shell or solid finite elements) and different mesh sizes. Moreover the shape and magnitude of an initial geometrical imperfection is also investigated. The numerical analysis were made with the Newton-Raphson procedure with geometrical and material nonlinearity. The numerical results were compared with the laboratory four point bending test of a thin-walled beam. Furthermore, some guidelines for numerical simulations of a short span thin-walled beams in bending were proposed by authors.

This paper presents a numerical study of a road barrier subjected to a bus crash test. The authors focus on the proper description of a barrier material model. Material model parameters are verified according to a simulated forming process. The solution uses modeling and simulation methods, as well as the finite elements method implemented with LS-DYNA software. The obtained results show that defining a proper road barrier model must consider the manufacturing process. Intensive plastic deformation leads to a significant increase in yield stress only in areas where the highest strain is observed during the forming process. The barrier model is divided into three zones, each of which have material properties characterized by different constants. The described construction, which uses homogenous material, is much more deformed and flatter than that of the improved model. Comparison with the experimental results shows that the new model better describes barrier deformation. In addition, deformation of the barrier under impact is evaluated according to European regulations (EN 1317). In comparison to the performed bus crash test, the crash test parameters obtained in the numerical simulation (static working width and normalized working width) gave more accurate results when the improved material model was utilized.This paper presents a numerical study of a road barrier subjected to a bus crash test. The authors focus on the proper description of a barrier material model. Material model parameters are verified according to a simulated forming process. The solution uses modeling and simulation methods, as well as the finite elements method implemented with LS-DYNA software. The obtained results show that defining a proper road barrier model must consider the manufacturing process. Intensive plastic deformation leads to a significant increase in yield stress only in areas where the highest strain is observed during the forming process. The barrier model is divided into three zones, each of which have material properties characterized by different constants. The described construction, which uses homogenous material, is much more deformed and flatter than that of the improved model. Comparison with the experimental results shows that the new model better describes barrier deformation. In addition, deformation of the ba...

This paper investigates the crack propagation and fracture failure of the gas turbine compressor blades on the vibrator rig. The blades used in the investigation were the newly qualified specimen from gas turbine factory, without any preliminary cracks or corrosion pits. The casting blades made of titanium alloy were entered into the transverse vibration in the resonant condition during the experiment. During the high cycle fatigue test, the growth of the crack was monitored and measured with the method of dye penetration. In the second part of work, finite element method (FEM) was utilized to calculate the stress distribution of the blade during vibration, and the first mode of transverse vibration was considered in the analysis. The maximum principal stress zone of the finite element model in the resonance condition was at the place where the crack occurred.This paper investigates the crack propagation and fracture failure of the gas turbine compressor blades on the vibrator rig. The blades used in the investigation were the newly qualified specimen from gas turbine factory, without any preliminary cracks or corrosion pits. The casting blades made of titanium alloy were entered into the transverse vibration in the resonant condition during the experiment. During the high cycle fatigue test, the growth of the crack was monitored and measured with the method of dye penetration. In the second part of work, finite element method (FEM) was utilized to calculate the stress distribution of the blade during vibration, and the first mode of transverse vibration was considered in the analysis. The maximum principal stress zone of the finite element model in the resonance condition was at the place where the crack occurred.

This paper presents investigation results on effect of neutron irradiation embrittlement on cyclic hardening behavior of core shroud assembly in pressurized water reactor under beyond-design basis earthquake (BDBE). In order to simulate the cyclic hardening behavior considering the neutron irradiation embrittlement, the previous user subroutines developed for monotonic hardening behavior were updated based on some cyclic hardening test results of irradiation-simulated specimens. Finite element (FE) elastic-plastic seismic analysis was performed by using Chaboche combined hardening models considering cyclic hardening or cyclic softening and a bi-linear kinematic hardening model. As a result, it is found that the bi-linear kinematic hardening model derived the most conservative results, and the Chaboche combined hardening model considering cyclic softening derived the analysis results close to those of the bi-linear kinematic hardening model. In addition, variation of the FE elastic-plastic seismic analysis results vs. neutron irradiation dose was investigated using the bi-linear kinematic hardening model. Finally, it is identified that von-Mises effective stress and plastic strain energy increase and equivalent plastic strain decreases with increasing the neutron irradiation dose.This paper presents investigation results on effect of neutron irradiation embrittlement on cyclic hardening behavior of core shroud assembly in pressurized water reactor under beyond-design basis earthquake (BDBE). In order to simulate the cyclic hardening behavior considering the neutron irradiation embrittlement, the previous user subroutines developed for monotonic hardening behavior were updated based on some cyclic hardening test results of irradiation-simulated specimens. Finite element (FE) elastic-plastic seismic analysis was performed by using Chaboche combined hardening models considering cyclic hardening or cyclic softening and a bi-linear kinematic hardening model. As a result, it is found that the bi-linear kinematic hardening model derived the most conservative results, and the Chaboche combined hardening model considering cyclic softening derived the analysis results close to those of the bi-linear kinematic hardening model. In addition, variation of the FE elastic-plastic seismic analysis...

In any engineering analysis or investigation, a complex system is first visualized as a physical model. Then the mathematical model of the same is developed, and then the further analysis is carried out. By this we get good knowledge of the behavior of the system at lesser costs. This paper presents a similar technique adopted for the study of vibration characteristics of SMA Hybrid Composite Beam (SHCB) with one end fixed. Free vibration study is undertaken on a SHCB which is constructed by reinforcing SMA wires in a matrix of epoxy resin along with glass fibers. Homogenization for the determination of effective properties of the composite is carried out based on rule of mixtures. Analytical calculations are done to estimate the static deflections and free vibration frequencies of the SHCB. Static FEA and free vibration analysis are conducted using ANSYS workbench. FEA results are substantiated with the theoretical values.In any engineering analysis or investigation, a complex system is first visualized as a physical model. Then the mathematical model of the same is developed, and then the further analysis is carried out. By this we get good knowledge of the behavior of the system at lesser costs. This paper presents a similar technique adopted for the study of vibration characteristics of SMA Hybrid Composite Beam (SHCB) with one end fixed. Free vibration study is undertaken on a SHCB which is constructed by reinforcing SMA wires in a matrix of epoxy resin along with glass fibers. Homogenization for the determination of effective properties of the composite is carried out based on rule of mixtures. Analytical calculations are done to estimate the static deflections and free vibration frequencies of the SHCB. Static FEA and free vibration analysis are conducted using ANSYS workbench. FEA results are substantiated with the theoretical values.

In this article an analysis of the cone-type rotary piercing process of seamless tubes by means of a finite element model is presented. The originality of the proposed study is the utilisation of the shear strain of the material for the experimental validation of the model. The cone-type rotary piercing process is a complex procedure in which the material is subjected to severe plastic deformation and to surface twisting that leads to shear deformations. In addition, extreme friction conditions and high temperatures occur during the process which increase the difficulty of the process itself and its simulation. Consequently, the experimental validation of numerical models of the process cannot be accomplished exclusively based on power and velocity terms, as it is usually done. Instead, in this paper it is demonstrated how still another experimental parameter is required for the correct simulation of the process, which is the shear strain of the material, measured through the values of longitudinal surface twisting. This way, a new methodology for the analysis of the cone-type piercing process is proposed in the paper, which establishes a relationship between the material contact with the elements of the piercing mill and the resulting power consumption, process performance, forces exerted and longitudinal surface twisting of the material. Thanks to this methodology, it is shown that the relation between the material contact with the mandrel and the rolls in their initial surface region is responsible for the process performance, while the contact with the rolls in the region where the tube exits the piercing mill defines the surface twisting of the material and thus its shear deformation.

The stent implants nowadays are wide used technique in the treatment of the cardiovascular diseases due to their long-term life cycle. This life time depends on the type of the deployment, material properties, loading conditions, design and patient anatomy. Present paper presents a study of the fatigue of a new stent design. The geometry is proposed by the firma ISMA EOOD, Sofia, Bulgaria. Stents from medical stainless steel Grade 316L have been exerted to simulation of their fatigue by using Finite Element Method (FEM). Comparison between stents with different struts width is performed. In this work we pursue the aim to reveal the mechanical properties and fatique behavior of a stent with a new original design, using time dependant study. The stress conditions during crimping and inflation of the stent are simulated to obtain the parameters of the virtually implanted graft. Additionally, new conditions are introduced, which imitate the influence of the heart pulse wave. An attempt to predict the failure time has been undertaken taking into account the geometrical design and loading conditions. Goodman analysis has been performed and Safety factor estimated.The stent implants nowadays are wide used technique in the treatment of the cardiovascular diseases due to their long-term life cycle. This life time depends on the type of the deployment, material properties, loading conditions, design and patient anatomy. Present paper presents a study of the fatigue of a new stent design. The geometry is proposed by the firma ISMA EOOD, Sofia, Bulgaria. Stents from medical stainless steel Grade 316L have been exerted to simulation of their fatigue by using Finite Element Method (FEM). Comparison between stents with different struts width is performed. In this work we pursue the aim to reveal the mechanical properties and fatique behavior of a stent with a new original design, using time dependant study. The stress conditions during crimping and inflation of the stent are simulated to obtain the parameters of the virtually implanted graft. Additionally, new conditions are introduced, which imitate the influence of the heart pulse wave. An attempt to predict the failure ...

The paper presents the results of computer modelling using FEA and experimental researches of the influence of technological parameters of burnishing rolling process on resistance to fatigue wear of shafts. For solution of elaborate equation of motion the explicit method was used. This allows to carries out the time analysis of the displacements, strains and stresses state’s in workpieces. In addition, the numerical analyses for the fatigue wear component after burnishing for low frequency loads were carried out. The results of the numerical analysis were experimentally verified by researching the surface layer after burnishing. In addition the shafts on fatigue wear were tested.The paper presents the results of computer modelling using FEA and experimental researches of the influence of technological parameters of burnishing rolling process on resistance to fatigue wear of shafts. For solution of elaborate equation of motion the explicit method was used. This allows to carries out the time analysis of the displacements, strains and stresses state’s in workpieces. In addition, the numerical analyses for the fatigue wear component after burnishing for low frequency loads were carried out. The results of the numerical analysis were experimentally verified by researching the surface layer after burnishing. In addition the shafts on fatigue wear were tested.

The chloride-induced corrosion of reinforcement used to be represented by Tuutti’s model with initiation and propagation phases. During the initiation phase chlorides penetrate the concrete cover and accumulate around reinforcement bars. The chloride concentration in concrete increases until it reaches a chloride threshold value, causing deterioration of the passive layer of reinforcement. Then the propagation phase begins. During the propagation phase steel has no natural anti-corrosion protection, a corrosion current flows and this induces the production of rust. A growing volume of corrosion products generates stresses in concrete, which leads to cracking, splitting, delamination and loss of strength. The mechanical response of RC elements to reinforcement corrosion has mostly been examined on the basis of a 2D cross-section analysis. However, with this approach it is not possible to represent both corrosion and static loading. In the paper a 3D finite element model of an RC beam with the two actions applied is presented. Rust is represented as an interface between steel and concrete, considering the volumetric expansion of rust.The chloride-induced corrosion of reinforcement used to be represented by Tuutti’s model with initiation and propagation phases. During the initiation phase chlorides penetrate the concrete cover and accumulate around reinforcement bars. The chloride concentration in concrete increases until it reaches a chloride threshold value, causing deterioration of the passive layer of reinforcement. Then the propagation phase begins. During the propagation phase steel has no natural anti-corrosion protection, a corrosion current flows and this induces the production of rust. A growing volume of corrosion products generates stresses in concrete, which leads to cracking, splitting, delamination and loss of strength. The mechanical response of RC elements to reinforcement corrosion has mostly been examined on the basis of a 2D cross-section analysis. However, with this approach it is not possible to represent both corrosion and static loading. In the paper a 3D finite element model of an RC beam with the two actions a...

Transportation, handling, vibrations can lead to dynamic loadings requiring the characterization of the safety of plastic-bonded explosives (PBX). One of the addressed situations is the fall of explosive on a surface. Knowing that initiation can occur at a lower height during a vertical fall of a projectile on an inclined target than on a horizontal one, devices were developed to determine the critical thresholds. In this paper, data obtained on four HMX and/or TATB-based PBXs using pendulum drop configurations are detailed. Two analytical models are compared to estimate the heat released by friction at the interface. The model proposed in this paper yields the better agreement with data, and with finite element numerical simulations of the oblique impact on a given PBX. Lastly, the mechanical dissipation at the interface is estimated using this model and the simulations. This paper confirms that PBX/target friction cannot be the heating mechanism leading to initiation during oblique impacts.

This paper presents modelling of both single and double-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical tests are described. The macroscopic constitutive model is based on the assumption that the sintered material is a continuous medium. The parameters of the constitutive model for material under sintering are determined by simulation of sintering at the microscopic level using a micro-scale model. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results. Moreover, numerical simulations are validated by comparison with experimental results. The simulations and preparation of the model are carried out by Abaqus FEA - a software for finite element analysis and computer-aided engineering. A mechanical model is defined by the user procedure “Vumat” which is developed by the first author in Fortran programming language. Modelling presented in the paper can be used to optimize and to better understand the process.This paper presents modelling of both single and double-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical tests are described. The macroscopic constitutive model is based on the assumption that the sintered material is a continuous medium. The parameters of the constitutive model for material under sintering are determined by simulation of sintering at the microscopic level using a micro-scale model. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results. Moreover, numerical simulations are validated by comparison with experimental results. The simulations and preparation of the model are carried out by Abaqus FEA - a software for finite element analysis and computer-aided engineering. A mechanical model is defined by the user procedure “Vumat” which is developed by the first author in F...

This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit.This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit.

This Paper combines the Dugdale’s Approach with Extended finite element method (XFEM) in order to estimate the Plastic zone length (PZL) for a straight edge cracked plate (SECP) under uniaxial tensile loading condition. Dugdale utilized a different approach to evaluate the PZL by nullifying the effect of singularity at the tip of the virtually extended crack by the applying a uniform pressure which is equal to the yielding stress. XFEM is utilized for analyzing SECP as it is more efficient and accurate as compared to other conventional numerical tools. In XFEM, crack can be extended without any re-meshing because elements near crack interface need not to conform the crack geometry.PZL for SECP is evaluated for crack length, a, varying in the range of 0.01 to 0.05 (m) in steps of 0.01 and load intensity (σ0/Y) ranging from 0.1 to 0.5 in steps of 0.1. Crack Position (h/H) is also varied ranging from 0 to 0.8 in step of 0.2 in order to analyse its effect on PZL. MATLAB is employed for Extended Finite element analysis of SECP under Plane stress condition. Four node Quadrilateral elementsare used for extended finite element analysis. The numerical results are validated by the experimental results from the available literature.This Paper combines the Dugdale’s Approach with Extended finite element method (XFEM) in order to estimate the Plastic zone length (PZL) for a straight edge cracked plate (SECP) under uniaxial tensile loading condition. Dugdale utilized a different approach to evaluate the PZL by nullifying the effect of singularity at the tip of the virtually extended crack by the applying a uniform pressure which is equal to the yielding stress. XFEM is utilized for analyzing SECP as it is more efficient and accurate as compared to other conventional numerical tools. In XFEM, crack can be extended without any re-meshing because elements near crack interface need not to conform the crack geometry.PZL for SECP is evaluated for crack length, a, varying in the range of 0.01 to 0.05 (m) in steps of 0.01 and load intensity (σ0/Y) ranging from 0.1 to 0.5 in steps of 0.1. Crack Position (h/H) is also varied ranging from 0 to 0.8 in step of 0.2 in order to analyse its effect on PZL. MATLAB is employed for Extended Finite element...

Fuel efficiency requirements demand lightweight construction of vehicle body parts. The usage of advanced high strength steels permits a reduction of sheet thickness while still maintaining the overall strength required for crash safety. However, damage, internal defects (voids, inclusions, micro fractures), microstructural defects (varying grain size distribution, precipitates on grain boundaries, anisotropy) and surface defects (micro fractures, grooves) act as a concentration point for stress and consequently as an initiation point for failure both during deep drawing and in service. Considering damage evolution in the design of car body deep drawing processes allows for a further reduction in material usage and therefore body weight. Preliminary research has shown that a modification of load paths in forming processes can help mitigate the effects of damage on the material.This paper investigates the load paths in Nakajima tests of a DP800 dual phase steel to research damage in deep drawing processes. Investigation is done via a finite element model using experimentally validated material data for a DP800 dual phase steel. Numerical simulation allows for the investigation of load paths with respect to stress states, strain rates and temperature evolution, which cannot be easily observed in physical experiments. Stress triaxiality and the Lode parameter are used to describe the stress states. Their evolution during the Nakajima tests serves as an indicator for damage evolution. The large variety of sheet metal forming specific load paths in Nakajima tests allows a comprehensive evaluation of damage for deep drawing. The results of the numerical simulation conducted in this project and further physical experiments will later be used to calibrate a damage model for simulation of deep drawing processes.Fuel efficiency requirements demand lightweight construction of vehicle body parts. The usage of advanced high strength steels permits a reduction of sheet thickness while still maintaining the overall strength required for crash safety. However, damage, internal defects (voids, inclusions, micro fractures), microstructural defects (varying grain size distribution, precipitates on grain boundaries, anisotropy) and surface defects (micro fractures, grooves) act as a concentration point for stress and consequently as an initiation point for failure both during deep drawing and in service. Considering damage evolution in the design of car body deep drawing processes allows for a further reduction in material usage and therefore body weight. Preliminary research has shown that a modification of load paths in forming processes can help mitigate the effects of damage on the material.This paper investigates the load paths in Nakajima tests of a DP800 dual phase steel to research damage in deep drawing processes....

This paper presents the characteristics of the process of longitudinal rolling of shafts and the geometry of the working section of forming rollers with a secant profile. In addition, the analytical formulae defining the geometry of a roller profile were determined. The experiments were carried out on shafts made of S235JR and C45 structural steels and the MSC.Marc + Mentat program was used for the numerical analysis of the rolling process based on the finite element method. The paper analyses the effect of roller geometry on the changes in value of the widening coefficient and the diameter reduction coefficient for the first forming passage. It was found that the mechanical properties of the shaft material have a slight influence on the widening coefficient. The value of the widening coefficient of the shaft increases with increase in the initial diameter of the shaft. Increasing shaft diameter causes an increase of strain gradient on the cross-section of the shaft.

Due to extensive usage of corrugated web in construction, this paper performs finite element analysis to investigate the web thickness effects on the bending behaviour of Triangular Web Profile (TRIWP) steel section. A TRIWP steel section which are consists two flanges attached to a triangular profile web plate. This paper analyzes two categories of TRIWP steel sections which are D×100×6×3 mm and D×75×5×2 mm. It was observed that for steel section D×100×6×3 mm (TRIWP1), the deflection about minor and major axis increased as the span length increased. Meanwhile, the deflection about major axis decreased when depth of the web increased. About minor axis, the deflection increased for 3m and 4m span, while the deflection at 4.8m decreased with increment the depth of web. However, when the depth of the web exceeds 250mm, deflection at 3m and 4m were increased. For steel section D×75×5×2 mm (TRIWP2), the result was different with TRIWP1 steel section, where the deflection in both major and minor directions increased with the increment of span length and decreased with increment the depth of web. It shows that the deflection increased proportionally with the depth of web. Therefore, deeper web should be more considered because it resulted in smaller deflection.

This paper presents a study on the ultimate load behaviour of corrugated girder webs under shear loading following nonlinear finite element analysis. Sensitivity analyses conducted herein are numbers of corrugation wave, elements density, initial imperfection and material nonlinearities. This paper aimed to investigate the influence of this sensitivity to the ultimate shear load, buckling and post-buckling behaviours of the corrugated web girder under shear loading condition. Two web thicknesses have been considered in the study, while flanges were designed to be strong enough to ensure the shear governed. The corrugated profiled geometry remained constant for all models. The ultimate shear loads were reported and compared with the existing theoretical design. Based on the numerical results, this sensitivity analysis does not have a major effect on ultimate shear load and post-buckling behaviours. However, when the girder is controlled by elastic buckling, the shear resistance is higher compared to the se...

This paper describes the testing of single-edge notched bend (SENB) specimens, which are used for fracture toughness tests, and the ductile crack initiation from the notch tip of the specimens. All of the specimens exhibited brittle fracture with relatively large ductile crack growth (from 1.0 to 4.8 mm). The paper also shows the ductile crack growth simulation using a damage model (Bonora model) for finite element analysis (FEA). FEA reproduced ductile crack growth observed in the SENB tests and the analysis results showed the effects of the ductile crack growth rate on stress distribution around the crack tips. In addition, the value of the Weibull stress was calculated in the paper, and the Weibull stress slightly decreased if the model had a higher ductile crack growth rate as compared with the model that had a lower ductile crack growth rate.

The paper deals with local stability of the thin-walled compressed flange of channel columns and beams made of aluminum alloy. The aim of paper is to find critical stress of local buckling of the flange member taking into account the web-flange interaction in linear and nonlinear elastic range of the member material. The governing differential equation of the problem is derived with aid of the principle of stationary total potential energy. The equation solution leads to the critical buckling stress and assessment of the number of half-waves in linear elastic range of the member material. Taking into account these results the analytical formula of the critical buckling stress in nonlinear elastic range is established using the tangent modulus theory and the Ramberg-Osgood stress-strain relationship. Finally the analytical results for simply supported members are compared with the FEM solutions and good agreement is observed.

The paper presents a mathematical and computer modeling of effective properties of porous piezoelectric materials of three types: with ordinary porosity, with metallized pore surfaces, and with nanoscale porosity structure. The described integrated approach includes the effective moduli method of composite mechanics, simulation of representative volumes, and finite element method.The paper presents a mathematical and computer modeling of effective properties of porous piezoelectric materials of three types: with ordinary porosity, with metallized pore surfaces, and with nanoscale porosity structure. The described integrated approach includes the effective moduli method of composite mechanics, simulation of representative volumes, and finite element method.

Sheet metal forming (SMF) simulations are used extensively throughout the development phase of industrial stamping dies. In these SMF simulations, the die and press are normally considered as rigid. Previous research has however shown that elastic deformation in these parts has a significant negative impact on process performance. This paper demonstrates methods for counteracting these negative effects, with a high potential for improved production support and a reduced lead time through a shorter try-out process. A structural finite element model (FE-model) of a simplified die is studied. To account for elastic deformation, the blankholder surfaces are first virtually reworked by adjusting the nodal positions on the die surfaces attaining a pressure distribution in accordance to the design phase SMF simulations with rigid surfaces. The elastic FE-model with reworked surfaces then represents a stamping die in running production. The die is now assumed to be exposed to changed process conditions giving an undesired blankholder pressure distribution. The changed process conditions could for example be due to a change of press line. An optimization routine is applied to compensate the negative effects of the new process conditions. The optimization routine uses the contact forces acting on the shims of the spacer blocks and cushion pins as optimization variables. A flexible simulation environment using MATLAB and ABAQUS is used. ABAQUS is executed from MATLAB and the results are automatically read back into MATLAB. The suggested optimization procedure reaches a pressure distribution very similar to the initial distribution assumed to be the optimum, and thereby verifying the method. Further research is needed for a method to transform the calculated forces in the optimization routine back to shims thicknesses. Furthermore, the optimization time is relatively long and needs to be reduced in the future for the method to reach its full potential.Sheet metal forming (SMF) simulations are used extensively throughout the development phase of industrial stamping dies. In these SMF simulations, the die and press are normally considered as rigid. Previous research has however shown that elastic deformation in these parts has a significant negative impact on process performance. This paper demonstrates methods for counteracting these negative effects, with a high potential for improved production support and a reduced lead time through a shorter try-out process. A structural finite element model (FE-model) of a simplified die is studied. To account for elastic deformation, the blankholder surfaces are first virtually reworked by adjusting the nodal positions on the die surfaces attaining a pressure distribution in accordance to the design phase SMF simulations with rigid surfaces. The elastic FE-model with reworked surfaces then represents a stamping die in running production. The die is now assumed to be exposed to changed process conditions giving an ...

This paper discusses a numerical investigation of thickness changes of Dyneema HB80, a cross-ply thermoplastic lamina, during a helmet thermoforming process. The main mode of deformation during the preform phase of manufacture is in-plane shearing of the fabric. A laminate undergoes varying degrees of shear to conform to the geometric variations over the surface of the preform shape. Decreases in areal coverage that occur with increases in the local shear angle will lead to a resulting increase in local thickness. During the consolidation phase, multiple preform layers are compressed in a set of matched tools, and the compounding of the thickness variations can adversely affect the uniformity of pressure distribution between matched die tooling. Pressure variations over the surface of the part can lead to incomplete consolidation of the ply stack, as well as weakened, resin-rich areas. Because wrinkling of the composite reinforcement, incomplete consolidation and resin-rich areas can result in a compromised structural performance, it is important that the manufacturing process be well understood so it can be designed to mitigate formation of such defects. In the current work, the material properties derived from shear, bending and tensile tests are implemented in a finite element model of the cross-ply lamina. The finite element model uses a hybrid discrete mesoscopic approach, and deep-draw forming of the material is simulated to investigate its formability to a hemispherical geometry. Thickening of the lamina resulting from shear deformation is investigated and incorporated into models single-layer preform simulations. The simulation results are used to inform the design of multiple-layer preforms to mitigate the development of thin regions and out-of-plane waves to ensure complete, uniform consolidation.This paper discusses a numerical investigation of thickness changes of Dyneema HB80, a cross-ply thermoplastic lamina, during a helmet thermoforming process. The main mode of deformation during the preform phase of manufacture is in-plane shearing of the fabric. A laminate undergoes varying degrees of shear to conform to the geometric variations over the surface of the preform shape. Decreases in areal coverage that occur with increases in the local shear angle will lead to a resulting increase in local thickness. During the consolidation phase, multiple preform layers are compressed in a set of matched tools, and the compounding of the thickness variations can adversely affect the uniformity of pressure distribution between matched die tooling. Pressure variations over the surface of the part can lead to incomplete consolidation of the ply stack, as well as weakened, resin-rich areas. Because wrinkling of the composite reinforcement, incomplete consolidation and resin-rich areas can result in a compromis...

This paper presents an approach for determining temperature distribution on a 2200A busway model. Solidwork software was used in order to create 3D modeling of busway model. This paper proposes a simulation model developed by coupling the multiphysics between electrical analysis and thermal analysis. The coupling was done by using ANSYS Workbench and ANSYS Maxwell. Basically, the electrical analysis is performed onwards busway model in order to get the value of ohmic loss which is heat loss from the conductors in the busway. The ohmic loss results will be imported to thermal analysis in order to get the temperature result as well as temperature distribution. First, the direct current loading of the busbar, which neglect the alternating current effects, was considered. Second, the alternating current loading of busbar was used instead of direct current loading. The model of the second approach gives much more accurate result in term of temperature difference. The presented model was validated against temperature measurement on real size busway under electrical loading. The obtained results show that a very good agreement between computed and experimental data. Once the verification of the model is done, the busway configurations setup behavior is studied. Increasing number of feeder affects thermal stress concentration on busway joint.

The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.