Tài liệu miễn phí Cơ khí - Chế tạo máy
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Rate-dependent strength and ductility of binder jetting 3D-printed stainless steel 316L: Experiments and modeling
The observations for the binder-jetted material therefore stand in stark contrast to those for SLM-made stainless steel which can provide an even higher yield strength than the wrought material. 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.
4/5/2023 4:20:46 AM +00:00
Finite element analysis of a self-propelled capsule robot moving in the small intestine
The findings of this work are valuable to provide design guidelines and an evaluation means for the researchers and engineers who are developing medical robots for bowel examination as well as the clinical practitioners working in capsule endoscopy.
4/5/2023 4:20:37 AM +00:00
Sequential elastic adaptive NS-FE analyses for lower-bound limit load determination of plane-strain structures
The paper proposes the sequential elastic analyses run within the node-based smoothed finite element (NS-FE) framework incorporating an automatic adaptive mesh scheme to converge the lower-bound collapse load limit of plane-strain structures.
4/5/2023 4:20:30 AM +00:00
Mixed Eulerian–Lagrangian shell model for lateral run-off in a steel belt drive and its experimental validation
A non-material shell finite element model is developed and applied to the example problem of a slack steel belt moving on two rotating drums. For the first time in the open literature we demonstrate an approach for predicting the time evolution of the lateral run-off velocity of the belt in response to its geometric imperfection and angular drum misalignment.
4/5/2023 4:20:21 AM +00:00
In-silico experimentations of multimode shock response of polyurea
In the final case study, Case Study III, the applied shear wave at ultrahigh strain rate generated secondary pressure and horizontal shear waves at the edges of the loading site, which complicated the loading scenario but provided new insight into the interaction of laser-generated shock waves within the solid. The results can be used to improve the analysis of experimental data to quantify the accompanying deformation and failure mechanisms of polymers subjected to hypervelocity impacts.
4/5/2023 4:20:13 AM +00:00
Reverse-twisting of helicoidal shells to obtain neutrally stable linkage mechanisms
The reversed region increases gradually, resulting in a constant reaction moment. Analytical, numerical, and experimental analyses are presented to reveal and quantify the constant-moment behaviour. 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.
4/5/2023 4:20:01 AM +00:00
High-velocity impact on composite sandwich structures: A theoretical model
The time and velocity at each stage was separately analysed within a wide range of velocities in order to see the stage contribution to the energy-absorption. The model was validated against experimental results obtained in the literature showing a good agreement in terms of the impact-residual velocity curve.
4/5/2023 4:19:50 AM +00:00
Scaled boundary finite element method for hydrodynamic bearings in rotordynamic simulations
In this study, a semi-analytical solution of the Reynolds equation based on the Scaled Boundary Finite Element Method (SBFEM) is developed to reduce the numerical effort of the overall simulation. In contrast to a purely numerical solution, the two-dimensional pressure field is discretized in only one coordinate direction, whereas in the other direction, an analytical formulation is used.
4/5/2023 4:19:43 AM +00:00
Comparisons between beam and continuum models for modelling wheel-rail impact at a singular rail surface defect
In this paper, we compare two types of commonly used wheel-track interaction models for wheel-rail impact problems, i.e., a beam and a continuum finite element model. We first reveal the differences between the impact forces predicted by the two models due to a typical rail squat using a time-frequency analysis.
4/5/2023 4:19:34 AM +00:00
From macro- to micro-experiments: Specimen-size independent identification of plasticity and fracture properties
The plasticity and fracture initiation model are then derived using the conventional macro- and micro-experiments. It is concluded that micro-testing provides a powerful means to characterize materials whose properties are homogeneous over a few hundred microns only.
4/5/2023 4:19:26 AM +00:00
Closed-form optimal calibration of a tuned liquid column damper (TLCD) for flexible structures
Results demonstrates that the proposed calibration procedure leads to a balanced frequency response curve and thus improves the performance of the TLCD comparing with the calibration procedure ignoring background flexibility.
4/5/2023 4:19:17 AM +00:00
Uncut chip geometry determination for cutting forces prediction in orthogonal turn-milling operations considering the tool profile and eccentricity
The model accurately determines the uncut chip geometry, validated theoretically against a CAD representation of the chip with errors below 3%. Furthermore, a set of milling trials was proposed to compare the chip mass and the cutting forces estimated by the model with those measured from the trials in torus and spherical profiles.
4/5/2023 4:19:04 AM +00:00
A comparison of two damage models for inverse identification of mode Ⅰ fracture parameters: Case study of a refractory ceramic
The numerical wedge splitting tests show that in the case of brittle materials, the lower post-failure stress limit defined in the concrete damaged plasticity model resulted in energy consumption for crack propagation exceeding the defined fracture energy (114% higher in the case of a brittleness number of 4.4).
4/5/2023 4:18:57 AM +00:00
Fluid-structure interaction effects during the dynamic response of clamped thin steel plates exposed to blast loading
This work presents results from a numerical investigation on the influence of fluid-structure interaction (FSI) on the dynamic response of thin steel plates subjected to blast loading. The loading was generated by a shock tube test facility designed to expose structures to blast-like loading conditions. The steel plates had an exposed area of 0.3 m × 0.3 m and experienced large deformations during the tests.
4/5/2023 4:18:46 AM +00:00
A duplex oxide cohesive zone model to simulate intergranular stress corrosion cracking
The model showed matching results for all duplex oxide combinations in varying stress, but the inner logarithmical oxide gave higher crack growth rates than the power law. The power law with the thicker inner oxide showed good results for the change of stress intensity factor and gave the best results when the yield stress was varied. Grain misorientation effect was higher for the duplex oxides with thicker outer oxides.
4/5/2023 4:18:37 AM +00:00
Impact of weld restraint on the development of distortion and stress during the electron beam welding of a low-alloy steel subject to solid state phase transformation
The weld-induced martensitic transformation suppressed tension or promoted compression in the EB weld and heat affected zone (HAZ). A steep gradient of residual stress exists, with high tensile stress concentrated in a narrow region immediately outside the HAZ.
4/5/2023 4:18:24 AM +00:00
Model updating of a scaled piping system and vibration attenuation via locally resonant bandgap formation
This study presents a Finite Element (FE) model updating methodology of a piping system and demonstrates vibration attenuation at its resonant frequencies using tuned local resonators distributed along its length. An experimental laboratory scaled version of a prototype piping system inspired from existing piping structures in the oil and gas industry is assembled to study its dynamic behavior under laboratory conditions.
4/5/2023 4:18:13 AM +00:00
A multiscale simulation approach to grinding ferrous surfaces for process optimization
Using a molecular dynamics (MD) model, we subject a nanocrystalline carbon steel work piece to grinding by hard alumina abrasives and study material removal and surface topography. A second, much larger MD model allows us to additionally study the microstructural and stress response of a polycrystalline ferritic work piece with a grain size that qualitatively reproduces macroscopic material behavior.
4/5/2023 4:18:04 AM +00:00
Rotational snap-through behavior of multi-stable beam-type metastructures
The results demonstrate that localization analyses are a cost-effective and reliable tool for predicting ductile failure, reducing the number of mechanical tests required to calibrate the MMC fracture model compared to the hybrid experimental-numerical approach usually applied.
4/5/2023 4:17:57 AM +00:00
Calibration of the modified Mohr-Coulomb fracture model by use of localization analyses for three tempers of an AA6016 aluminium alloy
This paper presents a novel calibration procedure of the modified Mohr-Coulomb (MMC) fracture model by use of localization analyses and applies it for three tempers of an AA6016 aluminium alloy. The localization analyses employ the imperfection band approach, where metal plasticity is assigned outside the band and porous plasticity is assigned inside the band.
4/5/2023 4:17:43 AM +00:00
Low-frequency tunable topological interface states in soft phononic crystal cylinders
The low-frequency tunable topological interface states with remarkable field enhancement may find a wide range of potential applications such as tunable energy harvesters, low-pass filters and high-sensitivity detectors for biomedical applications.
4/5/2023 4:17:35 AM +00:00
Fully-coupled computational modeling of the dynamic response of 1-3 multiferroic composite structures
In this research, a fully-coupled finite element-based Multiphysics computational study was used to investigate a multiferroic composite structure comprised of a Terfenol-D magnetostrictive cylinder and a lead zirconate titanate (PZT) piezoelectric cylinder in a concentric bilayer configuration.
4/5/2023 4:17:27 AM +00:00
The investigation of primary creep regeneration for 10%Cr martensitic steel: Unified constitutive modelling
The effectiveness of the developed model for describing the sensitivity of the PCR behaviour to different loading parameters (e.g. reverse-loading magnitude and duration) and to represent the effect of PCR activation on the overall strain accumulation behaviour of the material is discussed.
4/5/2023 4:17:16 AM +00:00
Mesoscale modelling of extended bearing failure in tension-absorber joints
This paper presents the development and validation of a mesoscale composites damage model for predicting the energy absorption capability of “tension-absorber” joints. Tension-absorber joints are composite bolted joints specially designed to absorb energy in a crash via “extended bearing failure”, which involves the bolt forcing its way through the composite over a long distance.
4/5/2023 4:17:02 AM +00:00
Property-map of epoxy-treated and as-printed polymeric additively manufactured materials
The resulting average moduli and strengths were compiled onto a property-map to delineate the property-process interrelationship of 3D printed ABS, including the effect of diluted epoxy treatment and the dependency of print orientation on its mechanical behavior. In general, the property-map defines the design envelope to gauge the mechanical integrity of 3D printed ABS in different modalities and directionalities.
4/5/2023 4:16:54 AM +00:00
Fracture response of resistance spot welded dual phase steel sheets: Experiments and modeling
In addition, a simplified surrogate model for use in conjunction with coarse shell element meshes is also calibrated. Simulations are performed of all structural experiments to assess the range of validity of the detailed and simplified FE models. It is found that the detailed model captures the experimentally observed failure modes including changes in the location of fracture initiation as a function of the loading, while the simplified model is able to predict the spot weld strength with reasonable accuracy.
4/5/2023 4:16:34 AM +00:00
Dynamic response of a non-classically damped beam with general boundary conditions subjected to a moving mass-spring-damper system
In this paper a semi-analytical approach to efficiently determine the dynamic response of an Euler-Bernoulli beam with general boundary conditions crossed by a mass-spring-damper (MSD) system is presented. Based on a dynamic substructuring technique (DST), the non-classically damped beam subsystem in modal state space representation is coupled with the interacting degrees of freedom of the MSD system by applying a generalized corresponding assumption.
4/5/2023 4:16:27 AM +00:00
GPU-accelerated meshfree simulations for parameter identification of a friction model in metal machining
Results of the present investigation demonstrate that: (1) friction modeling at the tool-chip interface has a remarkable influence on the numerical simulations of machining; (2) reliability of the friction parameters is substantially interrelated with the choice and reliability of the constitutive model parameters. As a result of this work, the error of force prediction in meshfree cutting simulations can be significantly reduced by adopting an enhanced friction model.
4/5/2023 4:16:14 AM +00:00
On contact problem for the microperiodic composite half-plane with slant layering
This paper deals with the plane frictional contact problem for the microperiodic composite half-plane with slant layering. Problem was considered as a contact of a non-deformable punch pressed into the composite half-plane with normal and tangential forces at the state of limit equilibrium.
4/5/2023 4:16:05 AM +00:00
An extended separation-of-variable method for the free vibration of orthotropic rectangular thin plates
This paper proposes a method to solve for closed-form analytical solutions of the free vibration problems of orthotropic rectangular thin plates with arbitrary homogeneous boundary conditions. This proposed method is called the extended separation-of-variable method, in which the mode functions are in a separation-of-variable form, and the frequencies in two spatial directions are mathematically independent of each other.
4/5/2023 4:15:57 AM +00:00