Improved ball-on-elastic-pad and ball-on-hole tests for silicon die strength

Punching shear is a type of failure of reinforced concrete slabs subjected to localized forces. This failure has been examined by many researchers experimentally, analytically or numerically. Empirical equations based on tests observations are nowadays the basis of the existing design codes. The work described herein presents 3D Finite elements method (FEM) analysis of three slab-column connections also tested experimentally to investigate the three fundamental geometries: central, side and corner column. The sensitivity of the FEM response to input parameters such as material constitutive laws is studied. Concrete constitutive models are described in detail, including their effects on the accuracy of FEM analysis. The comparison between FEM results, experimental tests, code provisions and a new model for punching based on the compression chord capacity model is presented. As a conclusion, an estimation of the model uncertainties related to FEM analyses of punching failures without shear reinforcement is discussed.

The three phase flux reversal machine (FRM) is a doubly salient permanent magnet machine with concentrated windings. This study proposes the distributed winding for this machine. This winding (i.e. full pitch winding) offers high-power density and improves the efficiency. The permanent magnet (PM) flux linking the stator winding has effectively two or four pole flux pattern, which depends on the number of stator poles and independent of number of rotor poles. Finite element method (FEM) analysis is performed on the concentrated stator pole winding FRM (CSPFRM) and proposed full pitch winding FRM (FPFRM) to obtain induced EMF, flux linkages and inductance of the winding. The inductance of both machines is also obtained using winding function approach and compared with FEM results. The effect of armature reaction is compensated by capacitive series compensation to improve the voltage regulation. FEM analysis is also carried out on both the compensated generators to evaluate the power density. Speed of the flux pattern and that of the rotor is different in FRM. The ratio of these two speeds is termed as fictitious 'electrical gear'. FRM and permanent magnet synchronous machine (PMSM) have sinusoidal terminal voltage and surface mounted PMs. The power density of both machines is compared using the concept of fictitious 'electrical gear'. To verify the above analysis, a 6/14 pole FRM with distributed and concentrated winding is designed and fabricated. The experimental results are in close agreement with simulated results.

The finite element method (FEM) analysis of elastic-plastic deformation was applied to examine the effect of surface texture controlling of dies by means of hybrid-shot (double shot by two different kinds of particles) treatment on the galling property applied to high tensile strength steel sheets. The FEM analysis results showed that the apparent friction coefficient, which was calculated from pressing load and the drawing force, increased with each increase in the pressing load. The experimental results from the drawing tests with lubricant oil showed that the friction coefficient of the die after hybrid-shot treatment decreased slightly with the increase of the pressing load. On the other hand, the friction coefficient of the die without shot treatment, (i.e. nearly flat surface), slightly increased with the increase of the pressing load due to the digging effect. These findings reveal that the effect of surface texture of dies was caused not only by the elastic-plastic deformation but also by the oil lubrication condition. The FEM analysis was therefore performed by taking into account the digging effect as well as the micro-oil pool effect. The experimental result in the case of hybrid-shot dies corresponds well to the FEM result by adopting the virtual oil model where the oil segment was defined as an elastic solid body.

This chapter introduces some principles and methods for designing modal test plans based on finite element method (FEM) results. The number of points in FEM is closed, generally in the thousands. From the FEM results, many orders of modal frequencies and vibration shapes can be obtained. However, in a modal test, only the foremost orders are concerned; thus, the number of measured points is limited, generally in the tens. There are 2–4 exciting points for a multi input multi output (MIMO) test, whereas 1 exciting point is practical for a single input single output (SIMO) test when the modes are not closed. When the number of foremost orders and measured points are fixed, it is not practical to automatically compute the position of the total measured points from the FEM results for several reasons. First, the computing work is very complex and time-consuming. Second, for the best mathematical results, some key points may be lost and some points that cannot be measured are included. Most importantly, none of these point are able to construct a regular plane, so the result is unacceptable aesthetically. The practical approach is to design an initial plan in which the position is measured manually according to common experience and the space is evenly distributed. By computing the maximum value of the un-diagonal elements of the modal assurance criterion (MAC) matrix and observing the modal shape animation of the simplified results, some measured positions can be modified. If some points need to be deleted in the initial base, this task can be completed automatically by dividing all measured positions into two groups: points that are allowed to be deleted and points that cannot be deleted. After the positions of all measurements are fixed, the number of exciting points and their positions can be obtained automatically according to the exciting energy distribution of different orders in each position.

The intensity and rigidity of cross-roll pipe straightener frame are analyzed with the Finite Element Method (FEM) and the stress of the frame is tested. The FEM results are compared with experimental results and the accuracy and rationality of FEA results are verified. The analysis results have significant guidance to design and transformation the structural type of cross roll straightener and its frame.

The strength and stiffness of 4300 rolling mill housing affect the quality of plate much. In presented research a problem that belongs to the stresses, deformations and modal analysis topic was investigated. The finite element method (FEM) and the electrical measuring method were used for the investigation. Modeling, meshing, loading and analysis on the housing are finished by Pro/E and Ansys 10.0. The dangerous point locates on the chamfer of upright and low carriage. The FEM results are larger than those of measuring by comparison. Natural frequencies and main vibration modes of the housing from first to fifteenth step are found. The dynamic bending and twisting deformation are the main factors which affect the dynamic characters of rolling mill. The middle of upright is the weakest position. The results of this article supply the basis for understanding the working state, maintenance and design of the 4300 rolling mill housing.

The interlaminar properties of a bond joint of stacked layers in a carbon fibre-reinforced composite with a thermoplastic matrix were evaluated under static loading. The un-precracked tension specimen with an external reinforcing layer was analysed in detail in the area of a bond joint. A detailed finite element method (FEM) analysis was performed to evaluate the influence of the bond joint shape on the interlaminar cohesive forces, which are simulated using the cohesive zone model (CZM). Simple lap and tapered joints were analysed. Continuum and shell elements were utilized in the FEM analysis, and the delamination results obtained using both solutions were compared to each other; however, no significant influence of the bond joint shape on the delamination onset was observed. The FEM analysis was supported using an experimental test on an un-precracked specimen made from prepreg with a carbon fibre fabric and a polyphenylene sulphide (PPS) matrix.

Cathodic protection (CP) anode bed grounding resistance calculating formulae, given by CP standards, are reviewed firstly. Underground assumptions and limitations of these grounding calculating formulae are analyzed, which means formula method may encounter problems when designing anode beds in high soil resistivity area. Based on finite element analysis (FEA) method, a new grounding resistance calculation method is suggested, which is can be treated as more suitable and flexible for anode bed grounding resistance calculation in high soil resistivity condition. The main steps of FEA method, geometric model building, meshing, boundary condition and solver setting, and grounding resistance calculating according to Ohmic law, are clearly presented. In order to introduce the FEA method in detail, a realistic anode bed design program for Northwestern China area, where soil resistivity is always very high, is demonstrated. Based field soil resistivity survey data by Wenner 4-pin method, the candidate anode bed site, named Station A, is regarded as optimal site, and Barnes’ soil layer analysis method is used to predict soil resistivity distribution in depth direction. Both formula method and FEA method are used to calculate grounding resistance. The following comparison results show that formulae from COR-GS-023, GB21448-2008, РД 153-39.4-039-99 standards and FEA method give out almost the same grounding resistance results under the assumption of uniform soil resistivity, which also, from another angle, verifies the correctness of FEA method. But for FEA method, designers can include realistic soil resistivity distribution function and any anode rod layout plan in calculation model. So, FEA method can be treated as a more flexible tool to calculate CP anode bed grounding resistance.

Prediction of the interpass temperature of a wire arc additive manufactured wall: FEM simulations and artificial neural network

The aim of this work is to carry out a study about wheel-rail and wheel-roller interaction. The final objectives are the determination of the hertzian contact ellipse, the maximum contact pressure and the pressure distribution in the contact zone, as well as the von Mises stress in the wheel for their application in the design of bogie test rigs. In order to accomplish this task, two models have been developed: an analytical one based on the Hertz contact theory, and a numerical one using finite elements method. Analytical model is implemented over MATLAB. By this way, it is fast and easy to test and analyze the wheel-rail, wheel-roller and wheel-2 rollers interaction: different roller radii and two loading cases: 50 and 100 kN per wheel. For the numerical model, it has been designed in CREO Parametric the same elements tested in the analytical model. Then these components have been simulated by means of finite elements in CREO Simulate, refining the mesh in the contact zone. Contact analyses have been performed in the same conditions as the previous model, and contact areas, pressures and stresses are obtained.

Springs are fundamental components in mechanical systems, crucial for ensuring the safety and functionality of mechanisms. Timoshenko’s stiffness formula accounts for both bending and torsional energy effects, providing accurate results for small deformations. However, when the deformation becomes large, the spring stiffness becomes a nonlinear problem due to the changing inclination angle and radius during deformation. In this study, we derive a formula for the cylindrical spring stiffness under nonlinear large deformation by considering two assumptions: the invariability of the polar angle at any point and spring wire length during deformation. This formula incorporates the effects of inclination and radius changes on the spring wire. We analyze the stiffness of the cylindrical spring with different initial inclinations using the finite element method (FEM). FEM results were compared with those obtained from Timoshenko’s formula, Hiroyuki’s formula, and the derived formula. For small deformations, the FEM results matched well with all three formulas. However, for nonlinear large deformations, the calculated results from Timoshenko’s formula showed a discrepancy of up to 32.58% compared to the FEM results. The modified Hiroyuki formula also exhibited slightly poorer agreement with the FEM results than the formula proposed in this paper. On the other hand, our derived formula demonstrated excellent agreement with the FEM results for nonlinear large deformations. Therefore, our stiffness formula for cylindrical springs is recommended for mechanical engineering spring design applications involving nonlinear large deformations.

To gain a better insight into the deformation and failure of reinforced sand retaining walls subjected to the vertical load from the crest and their associated reinforcing mechanisms, the model experimental results from well-controlled fully-instrumented load tests of full-scale reinforced sand retaining wall with sand backfill are simulated by making use of a nonlinear elasto-plastic finite element model considering strain localization. In the finite element method (FEM) analysis, the effects of the following factors for the filled sandy soil are taken into account: (a) the non-linear pre-peak work-hardening and post-peak work-softening; (b) effects of stress history and stress path; (c) the confining pressure dependency and strength anisotropy; (d) the stress-dilatancy characteristics; and (e) strain localization into a shear band(s) with a width proportional to the particle size. The load-settlement relationship obtained from FEM analysis is generally in good agreement with the physical experimental result. It is also found that the progressive failure with a development of shear bands and the horizontal earth pressure on the back of facing and the tensile force in the reinforcement layers can be reasonably simulated by the proposed FEM analysis.

Natural stone-paved roads have been generally used to preserve historical regions due to its architectural aesthetic aspect and environmental impact. However, there are limitations of travelling speed and traffic volume owing to the defects caused by the increased traffic loading and volume. To deal with these hindrances, ultra-rapid-hardening cement for both jointing and laying course materials in rigid small element pavement was considered. The objective of the present study was to continuously evaluate and compare the long-term performance of the suggested bound stone pavement throughout the various test criteria such as skid resistance and Falling Weight Deflectometer tests. The skid resistance outcome was met to the requirement and the response of deflection was measured following by related test method. To compare rut depth, the Finite Element Method (FEM) analysis was performed by modelling with material properties and by creating the loading cycle for imitating the Accelerated Pavement Testing (APT). The maximum deflections of asphalt, concrete block, stone A and stone B were calculated to 17.7, 6.1, 6.3, and 3.6 mm, respectively. Compared to the final outcomes of APT and FEM analysis, there was a difference ranging from 2.1 to 2.3 mm in bound stone pavement B and A, respectively.

This research was carried out to investigate the strain hardening in an aluminum alloy worksheet caused by punch/die shearing by means of microhardness measurement and finite element method (FEM) analysis. To examine the strain-hardened zone at the sheared edge of a worksheet, a 0.36 mm thick AA4047 aluminum alloy cut by punch/die shearing was subjected to microhardness measurements. In addition, a two-dimensional FEM model was developed and used to simulate the shear cutting of the aluminum alloy worksheet. The fundamental shear cutting parameters, punch/die clearance, cutting tool wear, and friction at the worksheet/tool interfaces were numerically varied and simulated. From the investigation results, the strain-hardened zone was observed by hardness measurement. The size of the zone significantly varied under different cutting parameters. From the simulated stresses at the sheared zone, the variation of the width of the strain-hardened zone with respect to cutting parameters was determined by the maximum principal stress on the worksheet being sheared.

Ultrasonic rotary motor which has hexadecagon shape stator was proposed. Stator of the hexadecagon ultrasonic motor was composed of an elastic ring and ceramics. The elastic ring had sixteen sides and sixteen angular points. Eight ceramics were attached on the outer surface of the eight sides of the ring. When two sinusoidal voltages which have 90 degree phase difference were applied to each four ceramics, elliptical displacements of inner surface of the ring were obtained. These elliptical displacements of the inner surface rotated the shaft rotor through the frictions. The proposed hexadecagon ultrasonic motor was designed and analyzed by using the finite element method (FEM). Based on the FEM results, the rotational speed of the fabricated motor was measured by changing the driving frequency and voltage. As FEM results, large displacements at contact points of the stator could be obtained from thinner elastic ring and also thinner ceramics. Rotational speed of 61 [rpm] was obtained from the fabricated motor by applying 10 [V] of alternating voltages.