Có 60+ tài liệu thuộc chủ đề "Mechanical sciences"
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Calibration of the modified Mohr-Coulomb fracture model by use of localization analyses for three tempers of an AA6016 aluminium alloy. Subsequently, localization analyses are used to establish the failure locus in stress space for proportional loading conditions and thus to determine the parameters of the MMC fracture model. By this approach, the valid- ity of the failure strain is confined...
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The design of mechanical metastructures is a rapidly emerging field, because of the potential to create unusual mechanical properties, such as ultra-high stiffness but lightweight [1–5. For exam- ple, arranging unit cells in a re-entrant pattern can result in a negative Poisson’s ratio of the macroscopic metastructure [14. tuneable me- chanical behavior, can be achieved by such metastructures. In light...
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We discuss which aspects of the grinding process or the work piece quality may be optimized using the adopted approaches, and we show that although our simulations span almost four orders of magnitude in length, the obtained material removal rates agree well. Mostly, grind- ing processes are optimized towards geometric shape of the work piece and its surface quality. Thereby,...
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The updated reduced order model is then used to investigate the creation of locally resonant bandgaps centered at the first three resonant frequencies of the structure by embedding tuned resonant cantilever beams with tip masses along the length of the piping system. Vortex Induced Vibration (VIV) can produce fa- tigue in the pipelines which in turn can lead to cyclic...
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Increasing the extent of the tack weld reduces the tensile stress, while increasing number of distantly distributed narrow tack welds does not help. The weld-induced martensitic transformation suppressed tension or promoted compression in the EB weld and heat affected zone (HAZ). These methods require understanding of the relations between thermal cycles, SSPT, microstructures and mechanical properties. Furthermore, it is still...
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Cohesive zone model Fracture mechanics Diffusion Duplex oxide Multi-physics Finite Element Model. The purpose is to investigate the crack growth effect due to different rate, compositions and kinetics of the duplex oxide. The finite element model is based on a coupling between cohesive zone formulation, slip-oxidation model and a diffusion model. The environmental properties in the slip-oxidation were obtained from...
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That is, the motion of the reflecting surface reduces the pressure acting on it. A basic understanding of the influence. and a possible interaction of the dynamic response with the positive phase of the load. However, exploiting this mitigation effect in the blast-resistant design requires a thorough under- standing of the governing physics in the problem.. and (3) use existing...
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The fictitious crack model has been used for simulation of the fracture process of refractories and concrete materials.. The present study investigates the effect of the lower post-failure stress limit of the softening law in the fictitious crack model by comparing an in-house developed subroutine for damaged elasticity model with the concrete damaged plasticity model implemented in Abaqus. The numerical...
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The model accurately determines the uncut chip geometry, validated theoretically against a CAD representation of the chip with errors below 3%. The experimental validation results correlate in both tests presenting in the case of the mass errors below 3.5% and the cutting-forces errors around 12%. 𝐹 𝑥𝑝ℎ𝑛 ( 𝜙 ) Phased force signal in X coordinate of the 𝑛 𝑡ℎ...
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An analogue 2-DOF model accounting for background flexibility is developed, which turns out to be a generalization of the classic 2-DOF model. The root locus analysis is performed to derive the optimal frequency ratio of the TLCD by the equal modal damping ratio criterion. Most of the studies were based on the classic 2-degree-of-freedom (2-DOF) structure-TLCD model, where one DOF...
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“macro-specimens ” which includes the measurement of the forces in the kilonewton range and displacements in the millimeter range. [15] made use of tensile specimens with 20 × 20 𝜇m cross-sections to characterize the strength and ductility of lath martensite, as well as to reveal the effects of the block and packet grain boundaries. Other examples of the use of...
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Both the magnitude and frequency content of the impact force need to be correctly modelled because they are closely related to the formation, deterioration and detection of such irregularities. The appropriate modelling of structural flexibility of the wheel-track system is of major concern for wheel-rail impact problems due to their high frequency na- ture [ 1 , 2. The second...
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𝜁 axial local coordinate of the FEM. 𝜂 circumferential local coordinate of the FEM or SBFEM. 𝜃 angular circumferential coordinate (rad) 𝜃 𝜀 angular position of the minimum gap (rad) 𝜆 eigenvalue. 𝜉 axial local coordinate of the SBFEM. 𝛼 within the circumferential range of the groove. ̄𝛼 outside the circumferential range of the groove Abbreviations. In Section 3 ,...
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The division of the stages was based on the physical interpretation of the perforation process involving reasonable hypotheses and simplifications. The model was validated against experimental results obtained in the literature showing a good agreement in terms of the impact-residual velocity curve.. In this sense, the determination of the presence of affected areas by the mentioned mechanisms has led to...
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Prototypes of the concept are employed in exemplary linkages to demonstrate the ability to create a large variety of neutrally stable compliant linkages, which require extremely low actuation forces and exhibit large ranges of motion.. Therefore, a significant part of the investigations on compliant mecha- nisms has been directed towards realising revolute joints [21–25] that mimic as much as possible...
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The results are presented in three case studies, where a different type of shock wave was emphasized in each case while focusing on the regions at the leading and trailing edges of the shock wavefront. Generally, the wavefront interacted with the accompanying and reflected waves, resulting in compromising the purity of the sought-after loading condition, especially during the return trip...
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𝑅, 𝐻, 𝐿 geom drum radius, centre-to-centre distance and cir- cumference of the drive. 𝜔, 𝑇 drum angular velocity and time period of a full revolution of the belt drive. 𝒊 , 𝒋 , 𝒌 basis vectors of the global Cartesian system. 𝑠, 𝜁 axial and lateral material coordinates of the reference configuration. 𝒈 , 𝒏 𝑔 , 𝒕 𝑔...
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Sequential elastic adaptive NS-FE analyses for lower-bound limit load determination of plane-strain structures. The NS-FE method simply adopts the low-order displacement functions, whilst the mesh adaptive algorithm employs the newest-bisection criteria with the novel modulus variation error indicators. The collapse load solution converges to the lower-bound limit at modest computing efforts, where the final NS-FE layout (namely fine meshes over...
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In addition, the mesentery was also considered as the intestinal boundary to restrict the mobility of the intestine. A typ- ical cross-section of the small-bowel wall is presented in Fig. (Colour online) (a) Cross-section of the intestinal wall. (b) Structure of the intestinal villi and crypt. (c) Peristalsis of the small intestine. (e) Segmentation of the small intestine.. (a) Physical...
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The observed stress-strain curve of the binder-jetted material always lies below that of wrought stainless steel 316L with a 50% lower initial yield stress and a 30% lower ultimate strength. From a mechanism point of view, the low mechanical properties of the binder-jetted material may be explained by the high initial porosity which is reminiscent of cast metals.. The known...