Papers by Keyword: FEM Analysis

Abstract: This study investigates the deformation behaviour of the CM247LC superalloy through a combination of physical experimentation and computational analysis. High temperature deformation was conducted at 600°C, 800°C, and 1000°C with a strain rate of 0.001 s⁻¹ and 50% of deformation. This research integrates microstructural analysis and mathematical equations to enhance understanding of the alloy's response under varying conditions. The findings reveal that at 600°C, the superalloy exhibits high flow stress and significant ultimate strength due to limited dynamic recovery (DRV) and restricted dynamic recrystallization (DRX). The increase in yield strength from 708 MPa at 600°C to 814 MPa at 800°C is attributed to effective precipitation strengthening from the γ' phases, corroborated by FEM simulations that show higher average yield strength values ranging from 875 MPa to 900 MPa at 800°C. Microstructural analysis indicates the role of finely dispersed carbides at lower temperatures and their coarsening at higher temperatures, which affects the material's strain-hardening behaviour and softening mechanisms. While physical simulations provide empirical data on mechanical properties and microstructural changes, FEM simulations predict stress-strain distributions and identify potential instability regions.

Abstract: The purpose of the suppressor is to partially eliminate the sound effect after firing and to mask the muzzle flame (essential for power components). When fired, the temperature rises approximately seven to ten degrees with each shot, assuming uniform temperature conditions of 21 °C. Given this knowledge, the suppressor can reach temperatures of 150 °C to 280 °C after firing one or two 30-round magazines. Assuming active training of the force or sport shooters, the suppressor will reach temperatures of 540 °C Celsius during continuous firing in an army combat situation, with temperatures in excess of 1000 °C. Already temperatures exceeding 280 °C during firing significantly affect the degradation of the suppressor material by thermal expansion through wear and tear, clogging by sediments in the case of frequent use of suppressors, massive deterioration by high temperature pressures and a significant reduction of the effect. Thermal deformation also has a significant effect, which can cause twisting or bending of the material, which can result in contact of the projectile with the suppressor and deflection of the projectile, in the worst case resulting in rupture of the suppressor and fragmentation of the projectile. Current knowledge, studies, professional articles published by the shooting public, representing the opinions and knowledge of the force components, sport shooters as well as hunters point to the lack of functionality, durability effectiveness of suppressors and point to defects, shortcomings during active use.

Abstract: This study addresses the reinforcement of corroded API 5L X42 pipelines using Glass Fiber Reinforced Polymer (GFRP) composite wraps, focusing on optimizing fiber orientation to enhance burst pressure performance. Pipeline corrosion poses significant risks to structural integrity and safety in the oil and gas industry. Experimental burst pressure testing, and Finite Element Method (FEM) were conducted to evaluate unidirectional (0/0/0), bidirectional (0/90/0) and multi-axial (0/45/-45) GFRP wraps. The FEM model, validated against experimental data, showed minimal error with 1.16%. Major findings show that the bidirectional had a maximum stress (501.29 MPa) and burst pressure (44.72 MPa) higher than the unidirectional and multi-axial. Better stress distribution given by the bidirectional structure helped to lower stress concentrations. These results show that pipeline repair techniques can be much improved by orienting fibers correctly. This study found that it helpful in field application of composite repair techniques for corroded subsea pipes.

Abstract: In cold forging, the temperature difference between the workpiece and the tool is small and thus deformation analysis is rarely coupled with thermal analysis. However, the friction coefficient of zinc phosphate coating with metal soap has a large temperature dependence. Consideration of the effects of workpiece and tool temperature change on the friction coefficient is thus expected to improve the analytical accuracy of cold forging. Thermally coupled cold forging analysis requires thermal conductivity, specific heat, heat transfer coefficient between the workpiece and the tool, in addition to the temperature dependence of flow stress and friction coefficient. The heat transfer coefficient between workpieces coated with zinc phosphate with metal soap and tools is investigated in this paper. Cold backward extrusion was performed with a 50% reduction of area, and the temperature history in the punch was measured with a thermocouple. The forging speed was 1, 3, and 10 spm. FEM analysis was performed to simulate the experiment by considering the temperature dependence of flow stress and friction coefficient. The heat transfer coefficient was estimated at 20 kW/(m2•°C) by comparing the experimental result and calibration curves.

Abstract: The application of Glass Fibre Reinforced Thermoplastics (GFRTP) is expected to reduce the weight of automobiles. In order to use GFRTP for automotive parts, it is essential to apply Computer Aided Engineering (CAE) technology. Until now, prepreg sheets with thermosetting resin matrix are assumed to be used for materials in simulation software. When FRTP is applied for materials in simulation software, it is required to grasp the characteristics of FRTP under moulding temperature. In our previous study, a system capable of evaluating the tensile properties of FRTP laminates at moulding temperatures had been developed and their tensile properties had been evaluated. Bending stiffness under moulding temperature is also required for simulation software. While bending stiffness can be determined using Young's modulus for isotropic materials, thermoplastic prepregs have large anisotropy, especially at moulding temperature. In this study, a system that enables self-weight deflection test of thermoplastic resin laminate under moulding temperature was developed and self-weight deflection characteristics of plain weave GFRTP were evaluated. The analysed results in which the bending stiffness under the moulding temperature of GFRTP was taken into account, gave the most suitable results to the experimental results.

Abstract: The Sanctuary of “Santa Maria delle Grazie” at Fornò is in the countryside near Forlì (Italy). The first edification time was in 1450, the today's configuration was reached at the beginning of the sixteenth century, due to various modifications: from static necessities to changes in tastes related to the time, as well as natural disasters and war damage. From a structural point of view, the Sanctuary is constituted by two masonry cylinders, without horizontal floors in elevation: the exterior cylinder around 33m diameter and 15m in height, with four semicircular niches protruding outwardly; the interior cylinder, the oldest temple, about 14m diameter and 20m tall, covered by a dome supported by an octagonal masonry structure. The space between the two circular structures is covered with a wooden roof resting on thirty-six main wooden beams. In the last years the Sanctuary has been subjected to numerous studies, surveys and analysis, including FEM structural analysis. In the latest studies we have assumed the Guidelines (2011) for the "Evaluation and Reduction of Seismic Risk of Cultural Heritage.". In the present work, following the entry into force of the new Italian rules NTC2018 and, more recently (February 2019), of the Explanatory Circular, which among other topics introduced significant changes in the field of existing buildings and in particular in the non-linear analysis mode, we have made a new update of the structural analysis and designed a series of works for restoration and anti-seismic improvement (also dehumidification works to mitigating the effects of decay caused by soaking on the mechanical characteristics of the masonry).

Abstract: The results of modeling of the influence of layers thickness of the Ni-Cr-Al composite on value of thermal stresses on its interlayer boundaries after diffusion annealing are presented. It is shown that the cooling of the AD1-Cr20Ni80 composite after annealing, which provides formation of a DZ at its interlayer boundary, consisting of three interlayers (CrAl₇, NiAl₃ + CrAl₇ and Ni₂Al₃ + CrAl₇), leads to spontaneous separation of the aluminum layer,due to the action of tensile stresses, exceeding the zone strength of the interlayer boundaries (CrAl₇) - (NiAl₃ + CrAl₇), and at k> 0.3 - (NiAl₃ + CrAl₇) - (Ni₂Al₃ + CrAl₇) with the ratio of layers thickness of aluminum and the alloy Cr20Ni80 - k <0.3, which leads to the formation of layered Cr20Ni80 / ( Ni₂Al₃ + CrAl₇) / (NiAl₃ + CrAl₇) or Cr20Ni80 / (Ni₂Al₃ + CrAl₇) coatings.

Abstract: Mechanical behavior of a rubber bushing of a stabilizer of a passenger car is studied in this article. An analysis of behavior of the bushing loaded in the axial direction is performed. An identification of the critical points in the bushing body and, especially, in the interface between the bushing and the stabilizer bar for later optimization of the whole system of the stabilizer fixing in the car construction is the aim of this work. An advanced FEM system including such effects as a strongly nonlinear strain/stress relation of material of the bushing (hyperelasticity), large displacements, large deformations, and contact between the bushing and the stabilizer bar was used for the numerical analysis.

Abstract: This paper describes a production process for experiment and finite element method (FEM) analysis of cold forming of SUS304 pipe. These large diameter pipes such as φ114.3 mm are used for a plant as a flow channel of gas and liquid. The connection of pipes are generally welded at the plant. However, the other connecting method are required from a viewpoint of making the plant environment worse by welding. Therefore, flaring process of large diameter pipes were proposed. This flaring process is one of a method of pipe flange forming. The formed pipes were connected used with loose flange. Flaring process was generally hot process, thus it has some problem such as becoming complex of forming machine and accuracy of dimension. In this study, cold flaring process of SUS304 pipe was proposed to satisfy these requisitions. Experiment and FEM analysis of cold flaring process were performed to clarify the optimum forming conditions for the flat length of connecting surface such as a diameter of punch, punch stroke and taper angle of dies. As a result, a gap between punch and die was needed to match the pipe wall thickness.

Abstract: The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the cracked area show that the crack was initiated by excessive accumulation of sulfide inclusions with an unfavourable banded structure that formed in the steel. An EDS analysis identified MnS involved in the crack mechanism.Moreover, an FEM simulation of the pressure distribution and an annulus model of axial loading were used to analyse the stress and strain values arising in the press casing under compression. It was found that normal compressive stresses in direction Z were much larger in the region where the crack occurred, which means that the press casing mechanical manufacturing process creates the largest stresses in the fillet radius area. On the other hand, the effect of sulphide inclusions in the material were also considered as a cause of failure.It is concluded that both these factors – equivalent stresses and the high level of sulphide inclusions in the steel structure have an impact on the press casing failure.