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• This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand. • The problem is formulated as a system of first-order differential equations with the known variables. • A user-defined SANISAND model is implemented as a subroutine, which is applied to FEM simulation. Sandy soil exhibits inherently anisotropy due to its microstructure, also known as 'fabric'. However, the drastic change in fabric observed during the dilatant phase is often overlooked in current cavity expansion research. This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand using a simple non-associated and anisotropic model, SANISAND. The problem is formulated as a set of first-order differential equations with the unknown variables as functions of an auxiliary coordinate, which can be solved as an initial value problem. A subroutine is implemented into the FEM simulation to verify the proposed method. Additionally, cavity expansion solutions in sand are compared with those based on state-dependent dilatancy. The anisotropic fabric of the sand is studied to investigate the impact of the initial void ratio, initial mean stress, and at-rest coefficient on the void ratio path, stress distributions and paths, and bounding surfaces. The proposed solution provides a framework for the potential use of cavity expansion in sand, considering the fabric change effect, and a benchmark for further developments and numerical calculations by using the SANISAND model. [ABSTRACT FROM AUTHOR]

A novel prefabricated curling rink supported by steel frame and precast concrete blocks has been tested by the 2019 China Youth Curling Open, and that will be responsible for the Beijing Winter Olympics and Winter Paralympics curling competitions in 2022. Due to quite limited researches on the mechanical properties of this professional curling venue, the dynamic behavior of the prefabricated rink under human activities are not well understood. In particular, people and curling stones are potentially more susceptible to the ice vibrations when compared to the traditional curling rink constructed on rammed foundation. Small ice rink vibrations caused by the human locomotion load can make athletes feel uncomfortable, which could affect competition experience, techniques, and skills of the occupancies. At the same time, it can also result in a slightly change of the curling stone trajectories, which ultimately caused the athletes to adopt an erroneous strategy. In order to get a further understanding of the above problems, this paper conducts a series of performance studies based on the 3D finite element model built in ABAQUS and the measured dynamic loads. In this context, it includes the research of on-site measurement of dynamic loads caused by different types of human locomotion on ice sheet, which can provide a reference to the dynamic performance design of prefabricated curling rink supported by similar structural systems. Moreover, the time and amplitude parameters of the footfall forces are extracted to analyze and be compared with the human induced loads results from the existing research, generally obtained on the concrete surface. Then, on the base of the finite element model verified by experiment, the experimental achieved loads are applied for the dynamic analysis to study the vibration acceleration and velocity response of ice sheet. Finally, the vibration response results, including peak acceleration (PA), vibration dose value (VDV), root mean square acceleration (RMS), as well as root mean square velocity were evaluated according to the regulations proposed by the International Olympic Committee and the vibration evaluation standards suggested by AISC design guide, ISO guideline, and VC curves. The analysis results indicate that innovation prefabricated curling ice rink supported by steel-concrete composite floors can meet the requirements of the event and has the prospect of promotion and application. [ABSTRACT FROM AUTHOR]

Surface enhanced Raman spectroscopy or surface enhanced Raman scattering (SERS) being a very powerful technique for quantitative and qualitative analysis finds application in low concentration detection of chemical and biological samples. In this work, we have presented a complete methodology of simulating nanoparticles-based SERS substrate. Different configurations namely single nanoparticle, dimer, trimer and tetramer nanoparticle clusters are simulated and enhancement factor for each configuration is estimated. Presented simulations are carried out with COMSOL Multiphysics software using Electromagnetic Waves module (Wave Optics) in frequency domain. The model of gold nanoparticle is established to determine the scatter field, which was further used to estimate the enhancement factor. Simulation results thus obtained are then validated with experimental results. The simulation study using the COMSOL Multiphysics tool helps in the design and development of the SERS substrate for maximum electromagnetic enhancement at a particular wavelength. The presented simulation methodology will be helpful for various SERS related computational studies in future. Presented approach helps in understanding the effect of various parameters such as particle size, inter particle gap, excitation wavelength, etc. on the EM enhancement. Simulating various possibilities before fabrication helps in saving money and time. For device realization, gold nanoparticles are synthesized using Turkevich method to achieve uniform and spherical nanoparticles. Synthesized nanoparticles (40–45 nm radius) were drop casted on a porous cellulose paper substrate to realize a SERS substrate. Nanogaps created between nanoparticles become the hot-spot locations leading to electromagnetic coupling and hence the Raman signal enhancement. Paper based SERS substrate is tested with Rhodamine B (1 μM) test sample. Enhancement of 106 was observed with the developed SERS substrate. UV–Vis spectrometer and Raman spectrometers are used for various characterizations. • The work presents the comprehensive simulation strategy for nano particle-based SERS substrates. • Simulation results present the effect of nanoparticle size and inter particle gap on Raman enhancement. • Different configurations namely, single particle, dimer, trimer and tetramer are simulated and results are discussed. • Gold Nanoparticles are synthesized and SERS substrate using paper is prepared for Raman enhancement and results are presented. • Presented work demonstrates a low-cost SERS substrate with its analytical and experimental investigation. [ABSTRACT FROM AUTHOR]

Accurate modeling or simulation of the vehicle-terrain interaction is critical for effective off-road vehicle navigation. While several high-accuracy methods exist (for example FEM simulation) they typically require computational capacity that exceeds what can be installed in a vehicle. Therefore, they are not applicable for real-time off-road vehicle navigation purposes, where computer hardware capacity is limited by the need for onboard installation. To address this challenge, simplified and less detailed models must be developed for real-time applications. This paper compares three different two-dimensional static terrain-vehicle models, considering accuracy and computational capacity requirements. Results of the comparison provide insights into the suitability of each model for real-time navigation of off-road vehicles. [ABSTRACT FROM AUTHOR]

• Ballistic gelatine demonstrates nonlinear viscoelastic behaviour at high strain rate. • The new constitutive model of the gelatine considers its peculiar properties. • The material parameters are identified based on experimental tests. • Numerical simulations of a bullet penetration through the gelatine are conducted. • Behaviour of the gelatine is well predicted by the formulated mathematical model. In the paper we formulated a new constitutive model for ballistic gelatine commonly used in shooting tests for military purposes. The model considers new effects that the gelatine reflects, i.e. non-linear viscoelasticity. The model was based on experimental tests including high-rate compression and stress relaxation tests. Our aim was to develop the mathematical modelling of ballistic gelatine and provide an easy-to-implement model to simulate ballistic tests. We implemented our constitutive equation to a finite element simulation of a bullet shooting through the gelatine block. The material constants were calibrated based on curve fitting method, i.e. we fitted the model to the experimental curves. The reliability of the constants values were confirmed by very good fitting and by validation of the model. The shooting simulation gave promising results which allowed us to observe realistic gelatine behaviour resulting from the bullet passage. The obtained results suggest that viscoelasticity plays an important role in the gelatine deformation and should be considered in mathematical modelling of its behaviour. [ABSTRACT FROM AUTHOR]

[Display omitted] • Theoretical formulas describing wave propagation in multilayer are derived. • The attenuation is dominated by physical properties of the interface and stride. • The attenuation is regulated by the ratio of single-layer thickness to the FWHM. • A novel dynamic design method for coatings is presented. Precision machining operations often lead to the failure of protective coatings on cutting tools due to common issues such as cracking, delamination, and peeling from cyclic impacts. While material selection and structural design are crucial for enhancing impact resistance, they primarily focus on static performance with limited consideration from the dynamic sights. This paper presents a novel dynamic design method for coatings, viewed through the lens of stress waves. We investigate the propagation behavior of stress waves in TaN/TiN and CrN/TiN coatings with layered structures. Our findings indicate that the attenuation of stress waves is dominated by the physical properties on both sides of the interface and the stride length. For interfaces with similar physical properties, the attenuation of stress waves is insensitive to the stride length, while for interfaces with different physical properties, the attenuation is regulated by the ratio of single-layer thickness to the full width at half maximum of the stress wave. These insights offer a strategy for extending the life of coatings and improving process safety under dynamic shocks. [ABSTRACT FROM AUTHOR]

The grind-hardening process aims to increase the surface hardness of the material through the dual action of the mechanical and thermal load. A novel approach to model the process and predict the hardness penetration depth was developed based exclusively on the prediction of austenite-martensite transformation. A combined micro and macro scale approach was implemented to forecast the temperature reached in the surface starting from the action of a single grain and using its specific cutting power to design a moving heat source representing the interaction between the grinding wheel and the material. The martensitic transformation temperature considered in this paper takes into consideration the fast heat cycle typical of this process. In order to validate the model, tangential surface grinding tests were performed on 42CrMo4 and microstructural analysis with micro-hardness measurements were performed. This research presents a first step in developing a grinding process simulation that includes multi-grain grinding, real grain geometries, binder effect, and real workpiece-grinding wheel kinematics. [ABSTRACT FROM AUTHOR]

Most used dental implants for human dental prostheses are of two steps type: first step means implantation and, after several months healing and osseointegration, second step is prosthesis fixture. For sure, dental implants and prostheses are meant to last for a lifetime. Still, there are unfortunate cases when dental implants break. This paper studies two steps dental implants breakage and proposes a set of instruments for replacement and restoration of the broken implant. First part of the paper sets the input data of the study: structure of the studied two steps dental implants based on two Romanian patents and values of the loading forces found in practice and specialty papers. In the second part of the paper, using DEFORM 2D™ FEM simulation software, worst case scenarios of loading dental implants are studied in order to determine which zones and components of the dental implant set are affected (broken). Last part of the paper is dedicated to design and presentation of a set for extracting and cutting tools used to restore the broken implant set. [ABSTRACT FROM AUTHOR]

Bulb turbine units are one of the most installed turbines in run-of river projects with relatively low head. In order to enlarge the useful life of these turbines and avoid fatigue problems and cracks, it is of paramount importance to understand and determine the most relevant parameters and their influence on the dynamic response of the structure. In this paper, the modal characteristics of a bulb turbine unit in operation is numerically investigated, considering the rotation effect. A FEM model including alternator, shaft, runner and fluid is developed and the boundary conditions are determined. Firstly, the modal characteristic of the runner under different blade opening are analyzed. Then the influence of the rotation on the modal characteristic of the shaft and runner is discussed. The numerical method is verified by comparing with experimental results of a rotating and submerged disk. The results show that the runner modes are mainly blade-modes，which can be grouped according to the blade number, one jellyfish mode and four local modes in each group. A modified Campbell diagram of the global modes and a transformation matrix of natural frequency between dry modes and wet modes are proposed. Results of this study helps to understand the most influencing parameters, such as the added mass effect of water combined with the rotation. The proposed modified Campbell diagram could be used for an accurate calculation of natural frequencies and avoid possible resonance problems in future designs of bulb turbine units. [ABSTRACT FROM AUTHOR]

This article presents a research study involving different simulations of crash tests by means of the finite element explicit dynamic software Ansys LS-Dyna to determine the roadworthiness of a fully composite chassis lightweight solar vehicle and its conformity to the World Solar Challenge (WSC) regulations. Furthermore, the paper describes the results of crash test simulations in conditions comparable with those of the standard homologation test, with an initial velocity of 15.5 m/s against a rigid barrier considering overlaps of 50% and 100%. The velocity measured at the base of the seat was later used in a sled test with a dummy to calculate the Head Injury Criterion (HIC), a number proportional to the probability of head injury caused by the impact. The values remained within the threshold of acceptability with overlap at 50% but exceeded the limit with the 100% overlap. With no load limiter implemented in the model, the seatbelt caused contact forces with the chest up to 14 kN against 6 kN of the typical load limiter used in road cars to limit damage to ribs and internal organs. Finally, the possibility of improving the front crash box was investigated by changing the crash box's planar sandwich structure with corrugated ones and layup without foam between the carbon layers. Various values of semi-amplitudes (A) of the sinusoidal profile have been tested. With a value of A of 6 mm, the capacity to absorb energy from an impact at 9 m/s was close to the original configuration. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical trimming process for hot stamped ultra-high strength parts was studied, in which the properties of fracture profile were analyzed and the effects of process parameters were evaluated. The research was carried out by FEM simulation with comparison and chosen of damage models, where the critical damage values were obtained through an iterative “predictor-corrector approach”. In addition, an experimental trimming tool was designed to study the effects of variable process parameters and verify the simulation results. By comparison, it was found that the Oyane damage model agreed with the experimental results better than others. The simulation and experimental results showed that the quality of trimmed hot stamped surface was poor with not straight profile and small burnish zone, but it can be improved by choosing proper trimming angle and blade radius. Such phenomena were discussed and explained in terms of stress state. Tensile stress accelerates the damage value while compress stress inhibits it. This paper helps to better understand the mechanical properties of hot stamped ultra-high strength steel. [ABSTRACT FROM AUTHOR]

Vibration problems of the building structures caused by technical seismicity are becoming an increasing topic. The aim of this paper was to realize the numerical analysis of soil-structure interaction (SI) in the area Modra - Slovakia and FEM simulation of the vibration wave s propagation from mechanical impact. For this purpose the variants of model by computing program Scia engineering has been created. It was also created geological model of subsoil in this area and processed frequency analysis of this model. These models are important for the assessment of the dynamic vibration transmissibility due to mechanical impact load properties. Another objective of this paper was to receive results from vibration wave's propagation FEM simulation mechanical impact involved which causes structural vibration in buildings including a process of the system SI due to accelerometers. Using of the theoretical analysis, experimental procedures results and FEM simulation of the vibration waves it seem to be the practical application for engineering practice in prediction and assessment buildings vibration due to seismicity induced by traffic. [ABSTRACT FROM AUTHOR]

Abstract: The paper reviews behaviour and calculations of axially loaded built-up columns. Calculations were performed according to Lithuanian national code STR 2.05.08:2005 [1] and EC3 [2]. FEM modelling was made as well. Build-up columns with different slenderness ratios of axes y-y and z-z were investigated. The paper deals with two different modes of buckling. The results of performed numerical experiments have suggested correction factors and appropriate buckling modes of the built-up columns. The obtained modelling results were compared with data on analytical calculations made according to STR and EC 3. The FEM analysis of the built-up column has showed that both codes (STR and EC3) are giving safe enough results (except one case) for a considered type of conditions for column support. [Copyright &y& Elsevier]

Abstract: The superficial mechanical properties of PVD films can be changed by micro-blasting. This process might induce a material deformation and herewith strength properties enhancement up to a certain depth from the coating surface. Depending on the micro-blasting conditions, the deformed film depth varies, thus affecting the coating''s performance in different applications. In the paper, a novel method is introduced for determining mechanical strength properties gradation in coatings after micro-blasting. Coated cemented carbides inserts were micro-blasted at various pressures. Employing the X-ray diffraction technique, the residual stresses were measured in the coating before and after micro-blasting and the related stress changes were determined at a certain depth from the film surface. These changes were compared to corresponding ones, calculated by a developed algorithm based on the Finite Elements Method (FEM). This algorithm describes the continuous penetration of individual blasting grains into the coating material and determines residual stresses after micro-blasting. Considering these results, the grain penetration depth and moreover, the developed distribution of the film yield stress after micro-blasting versus the coating thickness were estimated. To validate the captured gradation, this was taken into account in a FEM simulation of nanoindentation in micro-blasted TiAlN coatings. The obtained results were compared to corresponding measured ones leading to intuitively sound results. In all FEM calculations presented in the paper, only material stress–strain laws and no further physical or chemical properties were required. These laws were determined via nanoindentations and appropriate results evaluation. [Copyright &y& Elsevier]

Abstract: Bending has significant importance in the sheet metal product industry. Moreover, the springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of the manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (high strength low alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties are discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. The final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. This makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius, which can reduce the springback without cracking and damage of product. [Copyright &y& Elsevier]

Abstract: In nanoindentation procedures, due to indenter tip form deviations from its ideal geometry and the limited indentation depth, the contact region between the indenter and the specimen cannot be accurately determined. In this way, up to now, the hardness values are approximated by means of empirical methods with restricted accuracy, in a wide range of applications. In the frame of the present paper, the contact area between the indenter and the specimen during loading and unloading nanoindentation phases are defined through FEM supported calculations, thus enabling the hardness determination after various methods. The material constitutive laws required in these calculations are predefined by means of nanoindentations and a FEM-based evaluation of the corresponding results, considering the actual indenter tip geometry. In order to check the validity of the developed hardness determination procedure, various materials and coatings were tested through nanoindentations and their Vickers HV and indentation hardness H IT were computed and experimentally verified versus the indentation depth, by means of SEM-supported observations of the occurring impressions. Using the described methodology, coating thickness and substrate material effects on the film hardness can be predicted. Corresponding examples are illustrated in the present paper. [Copyright &y& Elsevier]

Abstract This paper presents an original optimization strategy implemented into milling operations performed on aerospace parts made of Inconel 718 superalloy. The optimization strategy includes the determination of more accurate constitutive material model (the J-C modified model) and adaptive control of the maximum values of the cutting force. It can be noted the constitutive material model was derived based on original experimental data obtained in the Laboratory for Aerospace Industry. The second task supports the CNC control program in the real time mode based on the changes of the effective feed rate when the values of the cutting force exceed the threshold values. According to the production outputs the optimization procedure applied leads to the improvement of the machining stability of thin-walled parts, the increase of the productivity and the reduction of machining costs. As a result, some important machining operations can be performed under High Performance conditions. [ABSTRACT FROM AUTHOR]

This paper presents a validated finite element modeling approach for simulating shear cutting, needing a minimal amount of experimental characterization. Only one uniaxial tensile test and one force–displacement relationship from a punching experiment are needed for calibration, with maintained prediction accuracy compared to more experimentally demanding approaches. A key ingredient is the observation that the Lode angle parameter is close to zero in the fracture region, postulating that the fracture strain only depends on stress triaxiality, with one free calibration parameter. The true stress–strain behavior is provided from inverse modeling of the tensile test, whereas the fracture model is calibrated using the punching test. The model is verified for different materials by comparing force–displacement curves for punching experiments not used in the calibration. The prediction error for the intrusion is below 4%. A validation is made for two setups. The local residual stresses are measured using Focused Ion-Beam Digital Image Correlation (FIB-DIC). The simulated values are within the experimental bounds. Cut edge morphology and plastic strains obtained by nano-indentation mappings are compared to simulation results, showing a decent agreement. For trimming, the cut edge morphology prediction performance decreases at 17% cutting clearance while it is maintained over the whole range for punching. The predicted hardness values have a mean absolute percentage error below 7.5%. Finally, the effect of element size and remeshing is discussed and quantified. The minimal experimental characterization and simulation effort needed, enables an efficient optimization of the cutting process in the industry. [ABSTRACT FROM AUTHOR]

In this paper, the finite element method (FEM) is used in order to develop a simulation of the mechanical performance of timber rounded dovetail connections between joists and beams under a fire event. The simulation is developed using the commercial FEM software ANSYS, and it is validated using the results of several experimental tests. These experimental tests were performed on spruce specimens as per the European regulations, and lasted for 30 min. The numerical simulation was developed using the methodology supported by the European regulations (Eurocode 5), and consisted of a transient thermal and static structural coupled system. Numerical results show a good agreement with the experimental ones, so ANSYS and the described methodology prove to be good tools to simulate the performance of timber dovetail connections under a fire event. Traditional failure criteria, which are useful at room temperature, such as Tsai-Wu one, are used in the simulation in order to predict the failure time, but it was demonstrated that this failure criterion is useless at high temperatures, as the ones reached under a 30-min fire event. [ABSTRACT FROM AUTHOR]

The focus of this paper is the dynamic shear characteristics of titanium alloy Ti-6Al-4V at large strain rates. Dynamic load testing of titanium alloy Ti-6Al-4V are performed by the split Hopkinson pressure bar (SHPB) at different strain rates, which involve the SHPB compression test and the SHPB shear test. The material behaviour during the tests are measured and recorded. The strain rates for the compression and shear tests range from 5.0 × 10 2 s −1 to 9.0 × 10 3 s −1 and 1.0 × 10 4 s −1 to 3.0 × 10 5 s −1 , respectively. The effect of competing mechanisms—strain rate hardening and thermal softening—on the adiabatic shear band is analysed. A size effect on shear band width is also found. According to the results, a modified Johnson–Cook (J–C) constitutive model is applied to tests at an ultrahigh strain rate. Furthermore, a finite element method (FEM) simulation is conducted to validate different aspects of the methodology. The SHPB shear test is confirmed as a process of pure shear. A comparison of the shear stress-strain curves from the mechanical tests and simulation show good agreement based on the modified J-C constitutive model. [ABSTRACT FROM AUTHOR]

Light-emitting diode (LED) drivers are widely regarded as the weakest link in the solid-state lighting systems. This paper proposes an improved thermal modelling process for the mission profile based lifetime prediction of reliability critical components in a LED driver for the outdoor lighting application. A converter-level finite element simulation (FEM) simulation is carried out to obtain the ambient temperature of electrolytic capacitors and power MOSFETs used in the LED driver, which takes into account the impact of the driver enclosure and the thermal coupling among different components. Therefore, the proposed method bridges the link between the global ambient temperature profile outside of the enclosure and the local ambient temperature profiles of the components of interest inside the driver. A quantitative comparison of the estimated annual lifetime consumptions of MOSFETs and capacitors are given based on the proposed thermal modelling process, and the datasheet thermal impedance models and the global ambient temperature. [ABSTRACT FROM AUTHOR]

This paper presents the layout of the about-ground weighbridge. There is requirement on the implementation of this device in order to re-measure the weight of the vehicles used for transportation of the steel waste collected to the collecting yard. The weighbridge is used wherever the vehicles must be weighed in order to not exceed the maximum permissible weight established in the legislation with regard to the transport of the goods by road. The advanced CAD / CAE systems used in the design and optimization contributed to carried out a number of modifications of the steel structure, reaching an ergonomic installation, weight saving, greater strength and rigidity of the structure when loaded. [ABSTRACT FROM AUTHOR]

In this paper, different apertures of superhydrophilic porous TiO 2 films are fabricated by sol-gel method with PEG2000 additive. The drag reduction effect of the films is investigated through experiment of falling-ball method and FEM simulation. The larger PEG2000 content, the bigger size and the more regular and homogeneous of the pores. The joint action of anatase crystal, hydroxyl groups and water molecules absorbed on the surface and porous structure causes the superhydrophilicity. The resistance test shows that when the addition amount of PEG2000 changes from 0.25 g to 2 g, the drag reduction efficiency increases from − 17.9% to 8.6% and − 16.8% to 9.4% with 12 mm and 25 mm diameter balls. The drag reduction mechanism can be obtained from Finite Element Method simulation. The result shows that vortexes are formed in the pore which can reduce the frictional drag by lowering the velocity gradient and giving a frictional driving force. Meanwhile, an “extra press drag” is formed between the front and back wall. If the degree of friction drag reduction is greater than the degree of press drag increase, the film will show the effect of drag reduction overall. [ABSTRACT FROM AUTHOR]

In this paper we propose a new Finite Element Modeling (FEM) strategy to simulate fretting wear profiles, taking account of the presence of a third body layer evolving over time. To validate this approach, the simulations were compared to experimental results on a gross slip Ti-6Al-4V cylinder/plane interface. A simple experimental procedure based on adequate superimposition of worn surface profiles allowed the estimation of individual cylinder and plane friction energy wear rates and quantification of the thickness of the third body embedded within the interface. A third body conversion factor, expressing the proportion of worn thickness transferred to the third body layer at a given position in the fretted interface was developed. The various quantitative variables were introduced in a coupled Matlab-Python-Abaqus algorithm where the worn thickness of counterfaces was simulated using a friction energy wear approach while the third body layer was progressively established by loading a “bell” thickness profile. The constant ( γ ) and parabolic distribution ( γ x ) of third body conversion factors were examined. Quantitative comparison with experimental results confirmed the interest of this new numerical strategy. Maximum wear depth, which was underestimated by nearly −80% using the wear model without taking account of the third body, was perfectly predicted, with error less than 10%, using the γ x third body model. Comparison with longer tests, up to 30,000 fretting cycles, confirmed the stability of the approach which, in addition to providing very good prediction of fretting scar profiles allows more conservative prediction of fretting crack risk. [ABSTRACT FROM AUTHOR]

When high speed machining polycrystalline metal, severe plastic deformation usually undergoes in the machined surface layer, accompanied by the microstructural variation of the crystallographic orientation. In the present paper, the machined surface plastic deformation and microstructural texture evolution during high speed machining of titanium alloy Ti-6Al-4V were investigated using finite element method (FEM) simulation. Firstly, a two dimensional FEM model was established, and was validated in terms of cutting forces and chip shape characteristics with experimental results of orthogonal machining. The plastic deformation on the machined surface was analyzed on the basis of finite element simulation. Results revealed that the plastic shear strain was much larger than the other strains in different directions. In addition, the variation of plastic shear strain and strain rate versus cutting time was obtained. When the feed rate was constant, the strain decreased and the maximum strain rate increased as cutting speed increased. Finally, the machined surface texture was simulated and analyzed using the Viscoplastic Self-consistent (VPSC) program based on the variation of plastic shear strain and strain rate, combined with polycrystalline plasticity theory. The machined surface texture evolution during machining was expressed by pole figures and orientation distribution function (ODF) diagrams. And the cylinder texture was identified from the pole figures. Four typical shear textures, including Y, C 1 , C 2 , and B fiber textures, were obtained from the ODF diagrams. Meanwhile, the orientation density of texture decreased with the increasing of cutting speed. [ABSTRACT FROM AUTHOR]

This paper describes the implementation and assessment of the predictive performance of a two dimensional mixed-mode fracture smeared crack model (MMFSCM) in a finite element method (FEM) based software. The referred constitutive model is based on the integration of the aggregate interlock and fibre pullout resisting mechanisms to simulate the behaviour of Fibre Reinforced Concrete (FRC) in both fracture mode I and II. The models used to simulate the contribution of each resisting mechanism predict the normal and shear stresses at the crack level based on the crack opening and sliding displacements. For this purpose, two aggregate interlock models and three fibre pullout models are used. The appraisal of this approach is conducted by simulating two numerical case studies consisting of a three-point notched beam bending test (3PNBBT) for assessing the structural behaviour in mode I, and shear panel tests to appraise the predictive performance of the model in mode II. In addition, modifications to the original formulation of the fibre pullout models are proposed, and a multi-linear branch model is also developed and implemented in order to facilitate the use of inverse analysis tools for defining the mode I behaviour. The numerical simulations have predicted with good accuracy the experimental responses, both in mode I and mode II, capturing not only the peak loads but also the evolution trend of the post-peak responses of the analysed scenarios. The modifications proposed to the fibre pullout models enhanced the overall predictive performance of the MMFSCM. The multi-linear branch model exhibited excellent performance, capturing the experimental response with very good accuracy in all 3PNBBT simulations. • Two-dimensional integrated mixed-mode smeared crack model for simulating FRC. • Aggregate interlock and fibre pullout models used to simulate the fracture process of FRC. • Implementation of the proposed constitutive model in a FEM based software. • Improvements were implemented in the fibre pullout models for increasing their predictive performance. • The good predictive performance of the MMFSCM is demonstrated by using experimental data. [ABSTRACT FROM AUTHOR]

The micro-milling process of brittle materials involves macro-scale tool and nano-scale cracks. This multi-scale coupling problem makes it difficult to accurately predict the milling morphology using conventional methods. In this paper, a novel method is proposed to predict the milled surface quality of brittle materials by the combined method of analytical model and finite element method (FEM) simulation. In the proposed method, the chip thickness model for inclined ball end mills was established. Thus, the multi-scale coupling milling process of fused silica was discretized into several nano-scale local cutting processes to accurately calculate the crack. The chip thickness, as the dominant factor to influence cracks of brittle materials, not only can be used to solve the multi-scale coupling problem, but can predict the crack distribution on the milling groves. In this paper, an instantaneous chip thickness model for inclined ball end mills was established. Then, the chip thickness and cutting force under different tool inclination angles were analyzed. Next, the chip thickness of serial characteristic positions were used as the cutting depth, and the nano-scale local simulations was carried out at several characteristic positions on the cross section of the milled grooves. At last, the milling experiments were carried out under different inclination angles and feed rates to verify the effectiveness of the proposed method. Besides, the collapse phenomenon on the upper surface and side surface was observed and discussed. [ABSTRACT FROM AUTHOR]

Flip anchors are a kind of ground anchor that rotate and open in the ground to attain pull-out resistance without the use of grout. Compared to ordinary grouted ground anchors, flip anchors can be driven into the existing ground quickly and are suitable for the emergency reinforcement of slopes. However, little research has been done on the slope reinforcement effect of flip anchors. In this paper, experiments on a model slope reinforced by plate anchors or flip anchors were conducted. During the experiments, vertical loading with a rigid loading plate was applied to the shoulder of the model slope to investigate its stability. Experiments were firstly conducted with and without model plate anchors under a plane strain condition. Then, experiments were conducted using actual flip anchors under a three-dimensional condition. In these experiments, the depth of the anchor plates, h , and the installation state of the anchor heads of the flip anchors (open or closed anchor head condition) were varied. After the experiments, corresponding numerical simulations (FEM) were conducted, and a subloading t ij model was applied to describe the soil behaviour. The numerical method used in this research successfully reproduced the reinforcing effect of the flip anchors. According to the test and calculated results, compared with the cases without reinforcement and with plate anchors, the effectiveness of the flip anchors for slope stability was verified. Moreover, the flip anchors installed under the closed anchor head condition required a larger displacement to produce a reinforcing effect than the anchors installed under the open anchor head condition. [ABSTRACT FROM AUTHOR]

This paper studies thickness and hardness of workpiece hardened surface layer, case of C45 steel orthogonal cutting, as function of cutting regime parameters and geometry of cutting tool. Simulations of orthogonal cutting using DEFORM 2D™ software are performed for different values of cutting speed, cutting depth, rake angle of the cutting tool and tool point radius, in order to determine the hardened workpiece surface layer thickness. Next, an experimental plan is set to validate simulations by means of cutting forces and hardness measurements. Taylor type new mathematical models of workpiece surface layer for stress, thickness, cutting forces and hardness are determined. [ABSTRACT FROM AUTHOR]

FEM simulation is known for its ability to simulate various cutting conditions in machining process and hence significantly reduce the number experimental trial to achieve the actual optimum cutting condition. This paper presents the capability of dynamic and non-dynamic cutting tool options that are available in the Third Wave AdvantEdge FEM software. The dynamic option was utilised for identifying the turning parameters for dimple structure fabrication and analysis of machining response such as cutting force and cutting temperature generated. The selected ranges of frequency which can be set in the dynamic assisted tooling for turning (DATT) along with other cutting parameters were simulated using dynamic cutting tool option resulted in stable wave shape that suitable for dimple fabrication. Furthermore, the simulation result also shows that cutting temperature and cutting force generated are smaller with a dynamic cutting tool than the non-dynamic cutting tool option. The dynamic cutting tool option in the Third Wave AdvantEdge was found to be very helpful and effective in determining a suitable range of cutting conditions and therefore, reducing the number of experiments for producing a dimple structure using the turning process. [ABSTRACT FROM AUTHOR]

The objective of this research is to define an optimized strategy for wire arc additive manufacturing (WAAM) process with a numerical tool. In this paper, a three-dimensional scaled steel plate model (120 mm × 24 mm × 6 mm) is built for numerical simulations to replace the expensive physical WAAM experiments. A series of thermo-metallo-mechanical analyses is conducted by using ABAQUS CAE user subroutines in which, thermal, metallurgical and mechanical models for gas metal arc welding (GMAW) process are implemented. Groups of variables in WAAM process namely wire melting current, voltage and torch moving speeds, as well as interval layer cooling coefficients, are chosen as input parameters of the artificial neural network (ANN). The two targeted values are hardness and ultimate strength of the steel plate model, which are obtained by fully coupled thermo-metallo-mechanical simulations or by quick results from commercial software JmatPro, and by real measurements on the test samples of WAAM experimental plates. In this primary study, Taguchi algorithm is used for data preparations of the numerical experiments. The tests are fulfilled with Neural Networks (NN) tool in MATLAB. A typical three-layer feedforward network is used for general works. The developed models show good prediction capability for hardness and ultimate strength. The ANN algorithm presents high potential in bidirectional modeling to develop the WAAM strategy tool. It is possible to realize the inverse modeling from properties obtained by fractions of phase volume to WAAM processing parameters. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent studies, some structures with alternating positive and negative Poisson's ratio have been proposed, which provides a new direction for structural design. The novelty of this paper is that the proposed structure can not only have different Poisson's ratio signs under tension and compression, but also adjust the Poisson ratio under tension or compression separately. The Poisson's ratio of the proposed cell structure under tension and compression is studied by FEM simulation and experiments. The results show that the Poisson's ratio under tension and compression has the opposite sign, and the value of the Poisson's ratio under tension or compression can be changed separately by adjusting the geometric parameters. The unique deformation law of the proposed structure does not depend on the material properties. 2D and 3D cellular structures composed of 2D unit cell arrays maintain these unique features. The proposed structure makes use of the self-contact effect, which provides a fresh perspective for the adjustability of the structural Poisson's ratio and structural design. • A novel cellular structure that can switch the sign of Poisson's ratio with loading state was proposed. • Poisson's ratio of designed 2D unit structure in either tension or compression can be adjusted independently. • The unique deformation law of the proposed structure is independent of the material properties. • 2D and 3D cellular structures composed of 2D unit cell arrays maintain these unique features. [ABSTRACT FROM AUTHOR]

The paper presents a measurement of temperature in a steelmaking furnace with an oxygen refining process, specifically in a tandem furnace. Knowledge of the temperature is important for optimizing the manufacturing process and extending of the life cycle of the inner furnace lining. Conditions in the furnace are very demanding; the temperature may temporarily exceed 2000 °C and exhibits changes of 60 °C s −1 . The atmosphere in the furnace is mainly oxidizing and its chemical composition is very variable. In the atmosphere there are also present liquid and solid compounds which act chemically and abrasively on the lining and on the sensor. These conditions make it impossible to use a suction pyrometer, contactless optical or acoustic measurement methods. It was decided to use a thermocouple in a protective tube. The sensor was inserted into the furnace through a steel bushing with water cooling. For the first measurement the type B thermocouple in Al 2 O 3 protective tube inside an outer shielding tube made from SiC was used. The second sensor used the type C thermocouple in a special thick-walled protective tube made from sintered SiC. The sensor does not measure the temperature of the gas itself, since it is affected by radiation of the surrounding areas. Conditions for heat transport from the furnace to the sensor are variable and difficult to determine; therefore, the accurate identification of the atmosphere temperature is not possible. Limit values of the temperature interval of the atmosphere were determined, for hypothetical cases of athermanous and ideally diathermic atmospheres. [ABSTRACT FROM AUTHOR]

The Tapered Double Cantilever Beam (TDCB) is the common specimen to study self-healing thermosetting polymers. While this geometry allows characterising the mode I fracture toughness without taking into account the crack length, the experiments show an important dispersion and unstable behaviour that must be taken into account to obtain accurate results. In this paper, finite element simulations have been used to understand the experimental behaviour. Static simulations with a stationary crack give the local stresses and the stress intensity factors at the crack tip when the TDCB is under load. In addition, the eXtended Finite Element Method (XFEM) has been used to make quasi-static crack propagation simulations. The results indicate that the crack tip has a curved profile during the propagation, advancing more at the edges than at the centre. The crack propagation begins when the applied load reaches a critical value. The unstable crack propagation noted in the experiments can be reproduced by introducing an unstable behaviour in the simulations. Finally, the sensitivity of the critical load has been studied as a function of the friction between pin and hole, tolerance of geometrical dimensions, and cracks out of the symmetric plane. The results can partially explain the dispersion of the experimental data. [ABSTRACT FROM AUTHOR]

The paper presents numerical simulations of punching shear in a reinforced concrete slab-column configuration formerly tested in the laboratory. A brief description of the test program at the University of Waterloo is reported. For the simulation, a symmetric quarter of the test configuration is employed. Full three-dimensional finite element discretized geometry is considered together with elastic–plastic reinforcement embedded as truss elements in concrete. Two regularized numerical models of concrete, formulated within elastic–plastic-damage theories, are applied. The first one, called gradient damage, is refined by an additional averaging equation where gradient enhancement involves an internal length scale. In the second one, called rate-dependent damaged plasticity model, a viscoplastic strain rate is introduced. The results for the first model implemented in FEAP and the second model from ABAQUS are discussed in detail. Different issues of numerical simulation to properly predict punching shear behaviour in the slab-column configuration are presented. [ABSTRACT FROM AUTHOR]

Abstract: Dynamic behavior of the forging machines is necessary to explore due to the increasing of speeds on large forging hydraulic presses for open die forging. The paper describes the modal analysis of two selected presses, which represent the most common designs of hydraulic presses for forging. The first press is with double-column frame CKV 50 with the force 50MN and the second one is with four-column frame CKV 170 with the force 170 MN. Further are described the simulations of oscillation, which was excited by time-dependent work force. Results of analysis are compared with measurement in the real operation. [Copyright &y& Elsevier]

Abstract: Vertical crankshaft forging presses are designed for precision die forging and calibrating large series, large dimensions and power demanding forgings. Forming is carried out in several die cavities with increasing complexity, for example, intended for the aerospace and automotive industries. Transfer of vertical forging press workforce is realized between crankshaft and ram through the inserted connecting rod and coupling or sliding joint. The accuracy of these presses is directly related to their stiffness. Designers are therefore looking for ways to increase the stiffness. One of the possibilities is to increase the rigidity of the transmission of power from the crankshaft to the forging. The subject of this paper is comparing the conventional press with power transmission using the crank mechanism and the press with yoke mechanism. [Copyright &y& Elsevier]

• Prediction of leakage current of a 20 kV polymeric insulator in the presence of real conditions of asymmetric non-uniform fan-shaped contamination by considering effective parameters associated with each shed such as electrical conductivity, segmental angle and thickness of contamination layer. • Proposing a hybrid finite element method (FEM) combined with the method of moment (MOM) to calculate leakage current with lower error values than the FEM simulation method compared to the actual values obtained from experimental test. • Perform experimental tests to validate the data obtained for training using neural network. • Reduce the error of insulator leakage current prediction values by multiplying the trained data. The accumulation of environmental pollution in symmetrical and asymmetrical categories conditions can lead to the aging of polymeric insulators through leakage current enhancement. In this paper, real asymmetric contamination, namely fan-shaped, is investigated accurately. However, the main approaches are that the real configuration of fan-shaped pollution is not normally uniform, and asymmetrically non-uniform fan-shaped pollution is detected. In particular, the segment angle, thickness, and electrical conductivity of the contamination layer are three major effective parameters in the insulation analysis of a fan-shaped polluted insulator. Finite element method (FEM) simulation and the proposed hybrid FEM combined with the method of moment (MOM) of a 20 kV polymeric insulator under asymmetric non-uniform fan-shaped contamination through leakage current calculations illustrate that variation in non-uniformity of related parameters of contamination layer are so crucial in the insulation situation of insulator. Also, leakage current is predicted using an artificial neural network (ANN) in processing obtained data from proposed methods, by applying effective parameters of non-uniform fan-shaped contamination. Experimental tests have been performed to validate the results and evaluate the leakage current of the fan-shaped polluted insulator. The results of the predicted values show that the difference is less than 5% compared to the actual values. [ABSTRACT FROM AUTHOR]

Abstract: The cutting material polycrystalline cubic boron nitride (PCBN) is ideally suited for machining of difficult-to-cut materials. It exhibits properties such as high hardness and high chemical stability at elevated temperatures. However, due to the occurrence of tribo-oxidation and abrasion during machining of hardened steels abrupt tool failure is common. The deposition of coatings offers a possibility to protect the PCBN substrate. Initial research results indicate that nanocomposite coated cutting tools show a significantly improved tool life and process behavior in hard machining. This paper describes the results of machining tests with uncoated and nc-AlTiN/a-Si3N4 and nc-AlCrN/a-Si3N4 nanocomposite coated PCBN tools with regard to the tool life and wear form. Additionally, the wear mechanisms abrasion and tribo-oxidation were investigated in model wear experiments. Furthermore, FEM cutting simulations were used to investigate the thermal interaction between substrate and coating. [Copyright &y& Elsevier]

In this paper, we present 3D finite element modeling and simulation of a CMOS MEMS single axis convective accelerometer. We describe the sensor architecture and present a sensor geometry model to be used in 3D FEM simulations. Differences between 3D and previously published 2D simulations are discussed. This work investigates 3D effects which give the opportunity to better predict not only sensor sensitivity but also power dissipation. Experimental sensitivity values and 3D FEM ones are compared for two different sensor geometries and two different heater temperatures. For a prototype having a heater-cavity border distance of 340µm and a heater length of 230µm, maximum sensitivity point is obtained for detectors localized at a distance of 125µm from heater center. This distance should be moved to 90µm if a 50µm heater length is used. So, detectors should be placed closer to the heater than the usually used mid distance. Moreover, optimal detectors location shifts closer to the heater as heater length shrinks. We also show that if heater length is reduced by 80% (from 230 to 50µm), then both electrical power and sensitivity decrease by 63% and 55%, respectively. So, best efficiency is obtained for shorter heaters. In addition, detector's length decrease is found to have a significant effect on sensitivity, with an increase of 58% and 87% using heater lengths of 230µm and 50µm, respectively. Here, detector's length decreased from the total side bridge length to a fraction of this length equals to 2.5%. Optimal length is obtained when detectors are implemented on the same side bridge fraction as that used to implement the heater on the central bridge. [ABSTRACT FROM AUTHOR]

Abstract: In deepwater S-lay operations, the combined influences of stinger curvature, axial tension and roller support force can induce very large plastic deformation in the pipe. Dynamic loads from vessel motion and pipe sliding down the stinger lead the cyclic plastic deformation. This paper investigates the cyclic plastic stress history of the overbend pipe subjected to the dynamic pipelaying loading. The dynamic roller support forces are obtained through an innovative large scale hybrid substructure experiment constructed to simulate the pipe-stinger impact behavior. The measured roller forces are used to verify a 3D finite element analysis results developed with ABAQUS/Standard to observe the dynamic pipe stress history. The results confirm that the roller support can induce stress concentration in the pipe and the combined dynamic pipelaying loadings can cause extensive cyclic plastic deformation. [Copyright &y& Elsevier]

Abstract: While alloy materials is irradiated by the high-intensity pulsed ion beams (HIPIB), the temperature distributions surrounding the primary heated regions used numerical analysis has been studied extensively over the past few years. Compared with the temperature distributions induced by HIPIB, few information is known about the temperature distributions on alloy materials used in practice as it is irradiated by the pulsed ion beams which possess characteristics of lower energy density and longer pulse width. The main reason is that the interaction between the alloy materials and the pulsed ion beams is only a few microseconds. It is difficult to detect temperature changes on alloy materials used in practice through traditional test. Ablation, melting, defects of microstructure on alloy materials are always used to validate the results of numerical analysis about the temperature distributions indirectly. In order to evaluate the temperature distributions directly, the dynamic thermal-dependent temperature behavior of the low-temperature alloy irradiated by the pulsed ion beams is investigated by experimental observation and finite element method (FEM) simulation in this paper. The temperature profiles generated from the interaction of μs-size between the alloy materials and the pulsed ion beams are evaluated by coupling characteristics of the low melting point and the pulsed ion beams. The FEM simulation results of the maximum temperature agree well with the experimental results on the surface of the low-temperature alloy. Results gained show that the maximum temperature on the surface of the low-temperature alloy irradiated by the pulsed ion beams can be applied to deduce the maximum temperature on alloy materials used in practice. [Copyright &y& Elsevier]

Abstract: In this paper, a three-dimensional finite element model is developed to simulate thermal history magnesium-based alloys during laser beam welding. Space–time temperature distributions in weldments are predicted from the beginning of welding to the final cooling. The finite element calculations were performed using Cast3M code with which the heat equation is solved considering a non-linear transient behaviour. The applied loading is a moving heat source that depends on process parameters such as power density, laser beam dimensions and welding speed, and it is associated to moving boundary conditions. Experiments were carried out to determine temperature evolution during welding and to measure the laser weld width. By comparing the thermal model answers with the measurements, it is found that numerical simulations results are in a good agreement with the experimental data. [Copyright &y& Elsevier]

Abstract: This paper reports the results of an experimental and numerical investigation on the non-linear behaviour and load-carrying capacity of CFRP-strengthened cold-formed steel lipped channel columns, devoting special attention to their local-plate and/or distortional buckling behaviours. A preliminary GBT-based study concerning the column elastic buckling behaviour is performed, focusing on determining the (i) sheet location (web, flanges and/or lips) and (ii) carbon fibre orientation (longitudinal, transverse or inclined) that optimize the strengthening procedure (enhanced buckling behaviour vs. cost). Then, an experimental programme comprising a total of 19 short and long fixed-ended lipped channel columns is described. The columns were strengthened with carbon fibre sheets (CFS) bonded at different outer surface locations (web, flanges or lips) and having the fibres oriented either longitudinally or transversally — since the aim of the study is to assess the influence of the CFS on the column structural response, bare steel specimens were also tested. The experimental results, which consist of non-linear equilibrium paths (applied load vs. axial shortening) and ultimate strength values (most of them associated with local-plate and/or distortional failure mechanisms), are subsequently used to calibrate and validate geometrically and physically non-linear numerical analyses based on shell finite element models and carried out in the code Abaqus. Finally, on the basis of both the experimental and numerical results obtained, some relevant conclusions are drawn concerning the most effective CFS location and fibre orientation to strengthen lipped channel steel columns affected by local-plate and/or distortional buckling. [Copyright &y& Elsevier]

Abstract: An experimental–numerical procedure for predicting the recrystallized structure in aluminum extrusion is presented here, altogether with its validation. The whole plan is carried out in three steps: in the first step, the evolution of microstructure of an AA6060 alloy during deformation was studied by means of small-scale laboratory test, the processing parameters being chosen in order to reproduce the typical industrial conditions. In the second step, the analysis of microstructure evolution after the heat treatment (550°C for 30min and 180°C for 10h) was analyzed, the obtained informations being used in order to fit a recrystallization model to be implemented inside the Deform FEM code environment. Finally, in the third step, the obtained informations are applied to extrusion tests presented in another papers by the authors (Schikorra, M., Donati, L., Tomesani, L., Tekkaya, A.E. 2007a. Microstructure analysis of aluminum extrusion: grain size distribution in AA6060, AA6082 and AA7075 alloys, J. Mech. Sci. Technol. 21, 1445–1451); the simulation results are compared and discussed with the experimental grain size distribution analyzed on the extruded rest. [Copyright &y& Elsevier]

Abstract: The present paper proposes a fabrication method of microneedles with various tip angles made of biodegradable polymer (polylactic acid, referred to herein as PLA). It was confirmed by the finite element method (FEM) simulation that the stress concentration occurs more severely at the tip area, as the needle becomes thin, and the tip angle becomes sharp. Photomasks for silicon cavities (negative dies for micromolding) with various tip angles are designed. The fabrication process involves etching a groove on the surface of a silicon die, molding the polymer into this groove, and then releasing it. The resistance force during inserting a fabricated needle to an artificial skin of silicone rubber was investigated. Effectiveness of sharp tip angle and thin shank for easy insertion is confirmed. Imitating the mosquito''s proboscis, the effectiveness of vibrating needle, and giving surface tension to the object surface was also confirmed. The combined needles like the mosquito''s proboscis, which are composed of a central straight needle and two outer jagged ones, are assumed. The effectiveness of these needles for easy insertion is three dimensionally investigated by the FEM simulation. Based on the result, the insertion mechanism of the mosquito''s proboscis is discussed. [Copyright &y& Elsevier]

Abstract: In the ISO 14577-4 standard various procedures for estimating the indenter area functions and the frame compliance Cf are proposed. Recently, a FEM-supported method performing a stepwise, trial and error simulation of nanoindentation, enabled the determination of materials stress–strain laws and moreover the precise mathematical description of an equivalent indenter tip geometry. An evolution of this method is presented in this paper, allowing the definition of the exact indenter inclination angle and of the indenters’ area functions as well (TiGAF algorithm: Tip Geometry & Area Function). Various materials, including coatings, Silicon (100), glass BK7, fused silica, tungsten, steel, etc were tested by nanoindentations and the related results were used to determine the indenter area functions, according to the aforementioned procedures by the TiGAF algorithm and after ISO14577-4 (method 3). A comparison of the obtained results revealed a good agreement. Furthermore, an effort to approach the stress–strain curves of a TiAlN coating, by assuming various indenter tip geometries, was realized by employing appropriate FEM-based techniques. The application of indenter tip geometries diverging from the determined one by the TiGAF algorithm led to significant deviations of the different stress–strain characteristics from the nominal ones. [Copyright &y& Elsevier]

Abstract: In this paper we describe a new accelerometer using ferroelectric material having a large dielectric constant, such as bulk PZT (ɛ r =2600). The measuring principle is detection of the capacitance change caused by the dielectric mass movement in the fringe electrical field. Considering practical fabrication, ferroelectric material is used for the substrate instead of the suspended proof mass. Since capacitance is increased electrically, and not mechanically, it is expected that the sensitivity will be considerably increased while retaining mechanical stiffness. This has the advantage of preventing touch down of the proof mass, and increasing the allowable measuring range of acceleration. The basic principle and the effectiveness of the proposed sensor are confirmed by both the theoretical calculation using an approximate model, and the finite element method (FEM) simulation. A practical sensor device was fabricated with basically only surface micromachining. A preliminary characterization was carried out under atmospheric pressure, confirming linearity between the sensor output and the input acceleration. The sensitivity is increased considerably (∼1000) compared to our previous sensor using polymer Parylene material having a comparatively low dielectric constant (ɛ r =3.15). [Copyright &y& Elsevier]

Abstract: A 100MeV H-compact cyclotron is being designed in China Institute of Atomic Energy (CIAE). It will provide a 75–100MeV, 200–500μA proton beam for various applications, including serving as a driving accelerator for RIB generation. In this paper, the basic magnet structure, 3D numerical simulation, magnetic material, mechanical design, deformation, imperfection field. will be described in detail respectively. In addition the preparation for construction will be discussed. [Copyright &y& Elsevier]