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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]

[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 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]

• 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]

• Finite element simulation of miniaturized housing structure for 3D packaged MEMS thermal wind sensor model. • Experiments are also done firstly, an agreement between simulation and experiment is obtained. • Provide a reference for the design and manufacture of MEMS thermal wind sensor miniaturization package. [Display omitted] This paper, for the first time, investigates the effects of miniaturized housing structure with various parameters on micro-electro-mechanical systems (MEMS) thermal wind sensors by simulation and experiments. Pillar diameter, number, height and curve-shaped top cover with different radian are considered to find out their influence on sensors performance. In the simulation, finite element method (FEM) software COMSOL is applied to simulate the 3D packaged sensor model. Then sensors with different housing parameters are tested in the wind tunnel based on thermal calorimetric principle, which uses flow-induced temperature gradient between symmetrically distributed thermistors to represent wind speed. An agreement between simulation and experiment is obtained, and the results demonstrate that the device's performance can be improved with smaller pillar diameter, more pillar number, and smaller pillar height. Moreover, the curved roof is designed, which provides a possibility for high wind speed measurement. [ABSTRACT FROM AUTHOR]

• A comprehensive simulation conducted to explore laser-ultrasonic waves in CFRP. • Derivations of temperature and thermal force fields due to laser absorption. • Investigations on the effect of oblique laser incidence. • Revealing the directivity of Lamb wave amplitude. • Experimental verification to guarantee the accuracy of the simulation results. Laser-ultrasonic waves are used in nondestructive inspections because they can be excited on arbitrarily shaped surfaces by irradiation of a pulsed laser from a distance. During the non-contact scanning of a laser, the waveform of excited ultrasonic wave is changed because the incident angle varies substantially. The change of the waveform will be more obvious for carbon fiber reinforced plastics (CFRP) laminates that have anisotropic properties. In order to guarantee the inspection, in this paper, we investigated the generation of ultrasonic waves in CFRP laminates by a laser irradiation with various incident angles and azimuth angles. Firstly, we constructed a simulation model: the thermal force field caused by the laser absorption is derived from a heat conduction equation, and it is introduced into an FEM software for analyzing the propagation behavior of generated ultrasonic waves. Then, the simulation result is compared with an experiment result. Through the FEM analysis, we found that the amplitude of the excited waves has an obvious directivity because of the strong anisotropy in the thermo-elastic property of the CFRP. In addition, the change in propagation behavior in the case of a small incident angle of 30° was found to be inconspicuous. However, when the incident angle of the laser beam is larger than 60°, the directivity pattern changes depending on the azimuth angle. Thus, it is important to control the incident angle and direction when a laser ultrasonic inspection is applied to CFRP structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Analysis of non-uniformly distributed loads' effects on SAW sensor's response. • A novel 2-D segmentation method to calculate SAW sensor's response under multiple patterns of load's distribution. • FEM simulation of R-SAW modes with and without SiO 2 load. • Fabrication of a series of two-port R-SAW resonators with different load patterns. To accurately calculate the response of surface acoustic wave sensors with non-uniformly distributed loads, a two-dimensional segmentation method suitable for various load distribution patterns was established with the idea of channelization. In this method, the sensitive area of the sensor was divided into several channels in the direction of the aperture, and each channel was cut apart into several cells along the direction of acoustic wave propagation. Finally, the two-dimensional analysis of the non-uniform distributed load was completed since each cell was analyzed and cascaded. A Rayleigh surface acoustic wave (R-SAW) sensor was used to simulate and experiment in this paper. The results showed that the responses of SAW sensors under loads with the non-uniform distributions were simulated accurately by using a two-dimensional segmentation method. [ABSTRACT FROM AUTHOR]

The trend of electrification and miniaturization brings the reliability of interconnects to the forefront. The solder joints are subjected to thermo-mechanical mismatch due to the Joule heating and electromigration (EM)-induced degradation under high current stressing conditions. However, most of the studies are limited to lab test samples or lab test conditions, which lack transferability in engineering applications. In this paper, automotive electronic components are studied subjected to field-like current pulse conditions. The work aims to understand the field-relevant failure modes of solder joints exposed to high current stressing via experimental and numerical investigations. Shunt components with and without Ni plating are analyzed in power cycling tests. A polarity effect is observed in the growth of intermetallic compounds (IMCs). The thickness of IMC at the anode exhibits an approximately linear growth with current stressing time, whereas the thickness of IMC at the cathode remains almost unchanged or slightly decreased. Ni, as diffusion barrier, serves to restrain Cu consumption from the terminals of shunts and also reduces Cu mass transport into and within the solder. The net Cu flux at the interface and in the solder is discussed to analyze the IMC growth kinetics. The shunts with Ni plating undergo less EM of Cu and yield longer lifetime. Voids and crack formation are detected in computer tomography (CT) scans and cross-sectional analysis by scanning electron microscopy (SEM). Finite element method (FEM) is implemented to simulate thermo-electro-mechanical fields of the assembly under power cycling test conditions. The distribution of divergence of material flux density corresponds well with the location of voids formation and provides good estimation for the lifetime. • Field-relevant failure mode of solder joints under high current loads is reproduced and investigated. • A polarity effect is observed in the growth of intermetallic compounds and shunts with Ni plating yield a longer lifetime. • Simulation is performed to characterize electromigration and thermo-mechanical fatigue of the solder joint. • Lifetime of the solder is proportional to the inverse value of divergence of material flux density. • With longer stressing time, the strain in solder joint will be increased owing to voids formation and coalescence of voids. [ABSTRACT FROM AUTHOR]

• Fibrous network materials are found to be insensitive to the crack when the crack length is less than a critical length. • The critical length of crack is three times as much as the average length of fiber segments. • Fiber re-orientation contributes to the enhancement of the crack resistance of the fibrous network materials. A 3D numerical model is established to characterize the fibrous network materials and the fracture behavior is investigated through the finite element method (FEM) analysis. The numerical results show that fibrous network material is insensitive to the crack when the crack length is less than a critical value, which is three times as much as the average length of fiber segments in the fibrous network. In addition, the toughening mechanism of the fibrous network material is revealed based on the FEM simulations. Due to the damage accumulation of bonds near the crack tip, the fibers around the crack tip are reoriented and become perpendicular to the crack path, which can further inhibit the crack propagation, and the deformation mode changes from bending-dominated deformation to tensile-dominated deformation, with the loading capacity of the fibrous network materials enhanced. The results in this paper demonstrate that the fibrous network materials show damage-tolerance to the small crack under the critical crack length, and the fibrous network formed by brittle fibers can exhibit ductile behaviors by controlling the microstructure and relative density, which is useful for the design and optimization of fibrous network materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]

This paper aims to model and simulate tool wear in drilling of Inconel 718 under two different cooling conditions, using an innovative numerical procedure. Although tool wear models can be implemented in most of finite element analysis (FEA) software to calculate the tool wear rate, there is a great limit due to the inability of all these software to update the geometry of the worn tool. In order to overcome this limitation, a subroutine able to modify the tool geometry based on a given tool wear model was developed and implemented in DEFORM 3D, an implicit FEA software. Experimental tests were performed to measure tool wear in drilling using conventional metal working fluids (MWF) and liquid nitrogen (LN 2) cooling. Experimental data were used to calibrate the tool wear model and to validate the drilling models. A comparison between simulated and measured results demonstrated the suitability of the developed drilling model to predict tool wear under both MWF and LN 2 cooling conditions. Therefore, the developed model can be efficiently used to evaluate the influence of the cutting conditions (including cooling conditions) on tool wear, minimizing the number of expensive and time-consuming tool wear tests. Image 1 • Development of an algorithm for tool geometry updating. • Tool wear simulation in drilling with tool geometry update. • Analysis of tool wear effect on machined surface. • Simulation of cryogenic cooling and conventional metal working fluids. • New procedure combining numerical and analytical models in one strategy. [ABSTRACT FROM AUTHOR]

• A simple method is proposed to obtain section resultant forces in 2D elements based on an interpolated stress field. • A novel membrane element is investigated in simulations of reinforced concrete shear walls. • Using 2D membrane elements with coarse mesh grids to model wall structures is possible. Numerical simulation of reinforced concrete (RC) shear walls is a challenging task, due to the intricate underlying mechanics and the difficulty in balancing computational cost and accuracy. In the previous work, a general–purpose four–node quadrilateral drilling element named as GCMQ has been developed by the authors. This new element performs well with coarse meshes and provides engineers an option to efficiently simulate planar problems, such as shear walls subjected to in-plane loadings. Meanwhile, GCMQ can recover nonlinear distribution of stress field so that section resultant forces can be explicitly integrated. In this paper, GCMQ is validated via numerical simulations of several RC shear wall specimens with different reinforcement schemes and geometries. Compared to experimental results, numerical models show that GCMQ can accurately simulate in-plane response such as pushover backbones with a relatively low cost for both short and slender walls. With proper material models, it is also possible to recover other quantities such as damage distribution patterns. Since GCMQ is essentially a microscopic finite element, convergence is guaranteed, local response can also be obtained with mesh refinement. GCMQ could be used as a good tool for future modelling of shear walls and similar structures. [ABSTRACT FROM AUTHOR]