Mechanical Simulation Research Articles

向日葵智能插盘晾晒机的设计与开发

In order to meet the demand for mechanisation of sunflower segmented harvesting and tray insertion for drying, an intelligent tray insertion dryer was designed and developed. The machine integrates the functions of disc picking, disc flipping, bar clipping, lifting and inserting, and uses SolidWorks for accurate mechanism design and simulation, incorporating the YOLOv5 model for efficient recognition of flower discs and the LeGO-LOAM algorithm for accurate navigation and map building. In the experiment, 81 sunflower samples were collected to analyse data on disc diameter, plant height, rod diameter and stalk diameter, and to verify the recognition accuracy of the YOLOv5 model in different directions. The results showed that the precision of disc recognition was 95.54%, accuracy was 89.94%, recall was 95.54% and F1 value was 0.89. Using the LeGO-LOAM algorithm tested at different path lengths, the root-mean-square error of the navigational build trajectory was 0.15 m, with a standard deviation of 0.10 m. This technological integration improves the operational efficiency and supports the mechanisation of sunflower insertion tray drying.

An Integrated Modeling Framework for Automated Product Design, Topology Optimization, and Mechanical Simulation

The present study introduces an integrated software approach that provides an automated product design toolkit for customized products like knives, incorporating topology optimization (TO) and numerical simulations in order to streamline engineering workflows during the product development procedure. The modeling framework combines state-of-the-art technologies into a single platform, enabling the design and the optimization of mechanical structures with minimal human intervention. In particular, the proposed solution leverages artificial intelligence (AI), shape optimization methods, and computational tools in order to iteratively optimize material utilization as well as the design of products based on certain criteria. By embedding simulation within the design optimization loop, the developed software module ensures that performance constraints are respected throughout the design process. The case studies are concentrated in designing knives, demonstrating the platform’s ability to reduce design time, enhance product performance and provide rapid iterations of structurally optimized geometries. Finally, it should be noted that this research showcases the potential of integrated modeling technologies towards the transformation of traditional design paradigms, in this way contributing to faster, more reliable and efficient product development in various engineering industries through the training and deployment of AI models in these scientific fields.

Engineering the Reaction Pathway of a Non-heme Iron Oxygenase Using Ancestral Sequence Reconstruction.

Non-heme iron (FeII), α-ketoglutarate (α-KG)-dependent oxygenases are a family of enzymes that catalyze an array of transformations that cascade forward after the formation of radical intermediates. Achieving control over the reaction pathway is highly valuable and a necessary step toward broadening the applications of these biocatalysts. Numerous approaches have been used to engineer the reaction pathway of FeII/α-KG-dependent enzymes, including site-directed mutagenesis, DNA shuffling, and site-saturation mutagenesis, among others. Herein, we showcase a novel ancestral sequence reconstruction (ASR)-guided strategy in which evolutionary information is used to pinpoint the residues critical for controlling different reaction pathways. Following this, a combinatorial site-directed mutagenesis approach was used to quickly evaluate the importance of each residue. These results were validated using a DNA shuffling strategy and through quantum mechanical/molecular mechanical (QM/MM) simulations. Using this approach, we identified a set of active site residues together with a key hydrogen bond between the substrate and an active site residue, which are crucial for dictating the dominant reaction pathway. Ultimately, we successfully converted both extant and ancestral enzymes that perform benzylic hydroxylation into variants that can catalyze an oxidative ring-expansion reaction, showcasing the potential of utilizing ASR to accelerate the reaction pathway engineering within enzyme families that share common structural and mechanistic features.

3D Stochastic Simulation of Rockfall Mechanism and Mitigation in the Batseri Zone

3D Stochastic Simulation of Rockfall Mechanism and Mitigation in the Batseri Zone

Protocols for Metallo- and Serine-β-Lactamase Free Energy Predictions: Insights from Cross-Class Inhibitors.

While relative binding free energy (RBFE) calculations using alchemical methods are routinely carried out for many pharmaceutically relevant protein targets, challenges remain. For example, open-source tools do not support the easy setup and simulation of metalloproteins, particularly when ligands directly coordinate to the metal site. Here, we evaluate the performance of RBFE methods for KPC-2, a serine-β-lactamase (SBL), and two nonbonded metal parameter setups for VIM-2, a metallo-β-lactamase (MBL) with two active site zinc ions. We tested two different ways of modeling the ligand-zinc interactions. First, a restraint-based approach, in which FF14SB zinc parameters are combined with harmonic restraints between the zincs and their coordinating residues. The second approach uses an upgraded Amber force field (UAFF) for zinc-metalloproteins with adjusted partial charges and nonbonded terms of zinc-coordinating residues. Molecular mechanics (MM) and quantum mechanics/molecular mechanics (QM/MM) simulations show that the crystallographically observed zinc coordination is not retained in MM simulations with either zinc parameter set for a series of known phosphonic acid-based inhibitors bound to VIM-2. These phosphonic acid-based inhibitors exhibit known cross-class affinity for SBLs and MBLs and serve as a benchmark for RBFE calculations for VIM-2, after validation with KPC-2. The KPC-2 free energy of binding estimates are within expected literature accuracies for the ligand series with a mean absolute error of kcal/mol and a Pearson's correlation coefficient of . For VIM-2, the UAFF approach has improved correlation from to , compared to the restraint approach. The presented strategies for handling ligands coordinating to metal sites highlight that simple metal parameter models can provide some predictive free energy estimates for metalloprotein-ligand systems, but leave room for improvement in their ease of use, modeling of coordination sites and as a result, their accuracy.

Effect of Fluorine on Formation of Hillock Defect in Copper Metallization and Methods to Remove Them

Abstract We have reduced occurrence of copper hillock defects in dynamic random access memory devices by 94% via silane and nitrogen purge, allowing fluorine adsorbed on surfaces of chambers from in situ NF3 plasma cleaning to react and be removed as gaseous SiFx. We have discovered these defects were more pronounced at grain boundaries where concentration of fluorine built up due to ion migration causing oxidation of metallic copper forming CuFx. COMSOL solid mechanic simulation confirmed that hillock formation is due to larger thermal expansion coefficient and molecular volume of CuFx causing inelastic deformation to relieve thermal stress.

Reference map technique for Lagrangian exploration of coherent structures

We explore the application of the reference map technique, originally developed for Eulerian simulation of solid mechanics, in Lagrangian kinematics of turbulent flows. Unlike traditional methods based on explicit particle tracking, the reference map facilitates the calculation of flow maps and gradients without the need for particles. This is achieved through an Eulerian update of the reference map, which records the take-off positions of fluid particles. This approach is found to be mathematically equivalent to the work of Leung (J. Comput. Phys., vol. 230, issue 9, 2011, pp. 3500–3524), who computed the flow map of simple two-dimensional flows using an Eulerian approach. We discuss important modifications necessary for its first application to complex three-dimensional turbulent flows, including the conservative, low-dissipation update of the flow map and the treatment of periodic boundary conditions. We first demonstrate the accuracy of finite-time Lyapunov exponent (FTLE) calculations based on the reference map against the standard particle-based approach in a two-dimensional Taylor–Green vortex. Then we apply it to turbulent channel flow at $Re_\tau =180$ , where Lagrangian coherent structures identified as ridges of the backward-time FTLE are found to bound vortical regions of flow, consistent with Eulerian coherent structures from the $Q$ -criterion. The reference map also proves suitable for material surface tracking despite not explicitly tracking particles. This capability can provide valuable insights into the Lagrangian landscape of turbulent momentum transport, complementing Eulerian velocity field analysis. The evolution of initially wall-normal material surfaces in the viscous sublayer, buffer layer and log layer sheds light on the Reynolds stress-generating events from a Lagrangian perspective.

The effect of maxillary premolar distalization with different designed clear aligners: a 4D finite element study with staging simulation

BackgroundMolar distalization with clear aligners (CAs) is a common treatment. However, when the molars reach their target position and the distal movement of premolars begins, the mesial movement of molars might reduce the overall efficiency of molar distalization. This study aimed to investigate tooth movement patterns under different CA designs in the premolar distalization stage using a four-dimensional mechanical simulation method.MethodsA finite element method (FEM) model encompassing the maxillary dentition, periodontal ligaments, attachments, and associated CAs was constructed. The simulation aimed to replicate a premolar distalization of 2 mm within 10 sequential steps. Buccal interradicular mini-implants were used. Three groups of CAs were designed: the conventional CA design group (Con group), the second molar half-wrap group (SMHW group) and the all-molar half-wrap group (MHW group). An iterative computational approach was employed to simulate prolonged tooth movement resulting from orthodontic forces. Additionally, morphological alterations in the CA throughout the staging process were simulated utilizing the thermal expansion method.ResultsCompared with the Con and SMHW groups, the MHW group presented significantly reduced mesial movement of the first and second molars. However, the MHW group presented the greatest displacement of canines and incisors. The distalization efficiency of premolars in the MHW group reached 95.5–96.5%, which was substantially greater than that in the Con group (84.5–85%) and the SMHW group (75–75.5%).ConclusionsThe four-dimensional mechanical simulation results indicate that during the process of premolar distalization with CA, removing the distal portion of the aligner covering the first and second molars (MHW group) can effectively reduce the mesial movement of molars. Consequently, this approach can increase the overall efficiency of molar distalization.

Quantum Mechanics/Molecular Mechanics Simulations for Chiral-Selective Aminoacylation: Unraveling the Nature of Life

Biological phenomena are chemical reactions, which are inherently non-stopping or “flowing” in nature. Molecular dynamics (MD) is used to analyze the dynamics and energetics of interacting atoms, but it cannot handle chemical reactions involving bond formation and breaking. Quantum mechanics/molecular mechanics (QM/MM) umbrella sampling MD simulations gives us a significant clue about transition states of chemical reactions and their energy levels, which are the pivotal points in understanding the nature of life. To demonstrate the importance of this method, we present here the results of our application of it to the elucidation of the mechanism of chiral-selective aminoacylation of an RNA minihelix considered to be a primitive form of tRNA. The QM/MM MD simulation, for the first time, elucidated the “flowing” atomistic mechanisms of the reaction and indicated that the L-Ala moiety stabilizes the transition state more than D-Ala, resulting in L-Ala preference in the aminoacylation reaction in the RNA. The QM/MM method not only provides important clues to the elucidation of the origin of homochirality of biological systems, but also is expected to become an important tool that will play a critical role in the analysis of biomolecular reactions, combined with the development of artificial intelligence.

A study on the structural characteristic of tire clamp using a new design method

The development of the new energy automobile industry has driven the development of the tire industry, and the development of the tire industry has put forward higher requirements for the handling and storage efficiency of tires. In this paper, through the discussion of the new tire synchronous fixture, the double parallel four-bar mechanism is introduced. The mechanism has the advantages of horizontal extension and contraction, and avoids the deviation in the vertical direction. In order to be better applied to the handling and storage of tires and further applied in other fields, this paper obtains the relationship between rod length and stroke through the kinematic analysis of double parallel four-bar mechanism, establishes a compact structure size table of common size, and carries out practical application simulation. The accuracy of size is verified by mechanical simulation. Through the relationship established in this paper and the compact structure size table, we can quickly and easily find the appropriate size of the double parallel four-bar mechanism according to the demand. Through the study of its structural characteristics, we can easily find the scene where it can be applied, so as to promote the universality of the application of the double parallel four-bar mechanism.

Bayesian modeling and mechanical simulations for fragility curve estimation of the mooring system of marine hydrokinetic devices

This work uses Bayesian modeling and mechanical model simulations through the Ansys-AQWA software to construct fragility curve estimates for marine hydrokinetic devices, more specifically, their mooring system. The fragility curves proposed here associate wind speed levels with the risk of damage to the equipment and could be used to better understand the susceptibility of these devices to damage from hurricanes. Our proposed modeling framework uses acoustic Doppler current profiler measurements from a site located off the North Carolina coast and the RM4 conversion device from the Sandia National Laboratory. By evaluating different scenarios with and without dynamic tension in mooring lines due to changes in current velocities caused by extreme wind speeds, our results indicate that the risks of damage may be significant depending not only on the average current velocity but also on the velocity variation.

Simulation of multi-stage attack and defense mechanisms in smart grids

Simulation of multi-stage attack and defense mechanisms in smart grids

Interception behaviors of mixed chlorinated hydrocarbons in groundwater by DDAC-amended LPBs: Control mechanism and CFD simulation

Low permeability barrier has emerged as a promising, cost-effective technology for anti-seepage and pollution mitigation in geotechnical engineering. However, its efficacy in organic pollution sites, particularly those contaminated with chlorinated hydrocarbons (CHCs) pales in comparison to its performance in areas contaminated by heavy metals. In order to rectify this deficiency, a novel bentonite backfill, modified with dihexadecyl dimethyl ammonium chloride (DDAC) and designated as DDAC-LPB, is proposed for use in low permeability barriers to contain CHCs in groundwater at contaminated sites. A series of rigid-wall permeability tests, mechanical properties tests, and diffusion tests were conducted to investigate the impact of CHCs solution on hydraulic conductivity, unconfined compression strength and adsorption properties of the LPB, respectively. The results reveal that LPB containing 10% DDAC modified bentonite exhibits excellent impermeability and mechanical workability, with a 2-5 fold increase in adsorption capacity, primarily driven by the hydrophobic interaction between CHCs and DDAC. Moreover, this study has innovatively applied computational fluid dynamics simulation to the field of solute transport modeling to evaluate the performance of DDAC-LPB in containing CHCs within lateral flowing groundwater. This novel approach was benchmarked against the widely embraced convection-diffusion equation modeling method, demonstrating a significant improvement in predictive accuracy. In a typical field scenario, the breakthrough time for CHCs using the DDAC-LPB technique ranged from 25.3 to 25.5 years, with a barrier thickness of 1 meter. This duration satisfactorily aligns with the expected service life of real-world projects. Overall, the DDAC-LPB has demonstrated superior performance and practical applicability in enhancing the containment of CHCs in contaminated groundwater.

Raman scattering of omphacite at high pressure: Toward its possible application to elastic geothermobarometry

Abstract Due to their widespread occurrence in several geological settings, omphacite inclusions could be used for elastic Raman geothermobarometry. However, the Raman scattering of complex silicate minerals entrapped in a host depends on both the chemical composition and elastic strain developed during the metamorphic pathway, which makes the task very challenging. Here, as a very first step to probe the potential of omphacite to be used as a mineral inclusion in elastic geothermobarometry, we report the pressure dependence of the Raman spectra of omphacite crystals with the same composition, approximately Jd43Di57, but having different symmetry because of the existence (P2/n) or absence (C2/c) of chemical order at the six- and eight-coordinated cation sites. The experimental results are complemented by ab initio quantum mechanical simulations on fully ordered omphacite (Jd50Di50). We demonstrate that the position of the well-resolved Raman peak near 688 cm–1, arising from Si-O-Si bond bending, is very sensitive to pressure but independent of the state of chemical order, which makes it promising to be utilized in Raman geobarometry. The width of this peak varies with chemical order but not with pressure and therefore can be used to constrain the temperature of inclusion entrapment, because the chemical order is indicative of the closure temperature of the cation-exchange reaction. However, further detailed analyses on the compositional variation of the Raman spectra of omphacite is required before considering omphacite-in-garnet systems to be suitable for Raman elastic geothermobarometry.

Sequential Multi-Scale Modeling Using an Artificial Neural Network-Based Surrogate Material Model for Predicting the Mechanical Behavior of a Li-Ion Pouch Cell Under Abuse Conditions

To analyze the safety behavior of electric vehicles, mechanical simulation models of their battery cells are essential. To ensure computational efficiency, the heterogeneous cell structure is represented by homogenized material models. The required parameters are calibrated against several characteristic cell experiments. As a result, it is hardly possible to describe the behavior of the individual battery components, which reduces the level of detail. In this work, a new data-driven material model is presented, which not only provides the homogenized behavior but also information about the components. For this purpose, a representative volume element (RVE) of the cell structure is created. To determine the constitutive material models of the individual components, different characterization tests are performed. A novel method for carrying out single-layer compression tests is presented for the characterization in the thickness direction. The parameterized RVE is subjected to a large number of load cases using first-order homogenization theory. This data basis is used to train an artificial neural network (ANN), which is then implemented in commercial FEA software LS-DYNA R9.3.1 and is thus available as a material model. This novel data-driven material model not only provides the stress–strain relationship, but also outputs information about the condition of the components, such as the thinning of the separator. The material model is validated against two characteristic cell experiments. A three-point-bending test and an indentation test of the cell is used for this purpose. Finally, the influence of the architecture of the neural network on the computational effort is discussed.

Impact of stress-induced precipitate variant selection on anisotropic electrical properties of piezoceramics

Precipitation hardening has been recently validated as a new mechanism for domain wall pinning and mechanical loss reduction in piezoelectrics. While anisometric precipitates have high pinning strengths, there is limited knowledge about the electrical anisotropy of the precipitation-hardened piezoceramics. In the present work, we successfully orient the precipitates in Li0.18Na0.82NbO3 piezoceramics by applying a uniaxial stress during the aging and studied its electrical anisotropy. Predicted by mechanical simulation and verified by transmission electron microscopy, it is demonstrated that the precipitate variant with its long axis perpendicular to the applied stress is energetically favored. The electrical anisotropy of the stress-assisted aged Li0.18Na0.82NbO3 is studied by applying electrical fields parallel or perpendicular to the stress axis. The domain wall contribution to permittivity is found to vary by more than a factor of two depending on orientation. In addition, the domain walls are more difficult to be activated by increasing the temperature when the electric field is perpendicular to the stress axis. Our work highlights the precipitate variant selection induced by stress-assisted aging and the related electrical anisotropy in piezoceramics. This technique enables the precipitate orientation in piezoceramics and the utilization of its anisotropy, providing fundamental insight into precipitate-domain-wall interactions and setting the ground for leveraging precipitation hardening effect in piezoceramics.

Numerical simulation of temperature distribution and residual stress in TIG welding of stainless-steel single-pass flange butt joint using finite element analysis

Abstract Controlling defects such as deformation in the weld joint and the residual or superfluous stresses due to tungsten inert gas (TIG) welding or arc welding is a major concern for many industries like aeronautical, automobiles, nuclear or atomic power plants, crude oil or fossil fuel industries where pipes are in use and circumferential welding is done. Arc welding is a metal joining process, and TIG welding is applied to many industrial sectors that require high-quality welding. Simulation has been done on single-pass TIG welding on the Flange pipe of SS316 to evaluate transient temperature, residual stresses, and distortion. First, a 3D model is developed and assembled in SolidWorks. Second, in an MSC Patran, preprocessing of the FE model is done. Finally, in MSC Marc, thermal and mechanical simulation is performed. Based on this simulation, the accuracy of welding of the flange–butt joint made of SS316 is validated. In this study, the information regarding simulation of temperature dispensation and residual or superfluous stresses is done on the flange–butt joint, and it found the stresses are compressive at the weld bead area, and along the transverse direction, stresses changed to the tensile. The experimental data show that the steep curve at 0.00 mm represents a maximum temperature near the weld path at approximately 2,352°C, and the slant curve shows the far away points from the weld path. Comparing it with FE analysis, the maximum temperature attained was around 2,539°C. An approximate deviation of 7.365% was observed. The results of the study will provide experimental and simulation analyses for the welding of pipes of stainless steel for the transportation of oil and gases in the petroleum industries.

A kinematically reasonable mechanism of tongue forward protrusion considering hyoid bone movements

The tongue has a wide variety of motor functions, which are driven by tongue muscle contractions and associated with movements of the hyoid bone (HB) connected to the tongue root. HB movement has been observed in many situations, including swallowing, breathing, and speech. However, the relationships between HB movement and tongue kinematic function have received little attention, and have not been considered in most previous biomechanical tongue modeling research, except studies of swallowing. The current study aimed to clarify the effects of HB movement on tongue kinematics during tongue forward protrusion, which is an essential tongue motor function associated with speech disorder. HB displacement during tongue forward protrusion was quantified using ultrasound imaging in four healthy controls. Furthermore, computational mechanical simulations of tongue forward protrusion were conducted with observed HB movements and active contraction of the genioglossus (GG) muscle, which is conventionally considered to be the driving muscle in tongue forward protrusion. Ultrasound imaging revealed anterosuperior HB displacement in tongue forward protrusion, with a similar magnitude in each direction (anterior: 6.3 ± 2.8 mm, superior: 5.8 ± 1.6 mm). Computational simulation demonstrated that the HB movement described above caused not only anterosuperior displacement, but also forward rotation of the tongue body, which was caused by kinematic constraints of GG. The resulting anterior displacement of the tongue tip was 1.5 times greater compared with that without HB movement. These findings indicate that the HB and associated tongue body movements play non-negligible roles in the tongue kinematics of forward protrusion.

Modeling and Visual Simulation of Bifurcation Aneurysms Using Smoothed Particle Hydrodynamics and Murray’s Law

Aneurysm modeling and simulation play an important role in many specialist areas in the field of medicine such as surgical education and training, clinical diagnosis and prediction, and treatment planning. Despite the considerable effort invested in developing computational fluid dynamics so far, visual simulation of blood flow dynamics in aneurysms, especially the under-explored aspect of bifurcation aneurysms, remains a challenging issue. To alleviate the situation, this study introduces a novel Smoothed Particle Hydrodynamics (SPH)-based method to model and visually simulate blood flow, bifurcation progression, and fluid–structure interaction. Firstly, this research consider blood in a vessel as a kind of incompressible fluid and model its flow dynamics using SPH; and secondly, to simulate bifurcation aneurysms at different progression stages including formation, growth, and rupture, this research models fluid particles by using aneurysm growth mechanism simulation in combination with vascular geometry simulation. The geometry incorporates an adjustable bifurcation structure based on Murray’s Law, and considers the interaction between blood flow, tissue fluid, and arterial wall resistance. Finally, this research discretizes the computation of wall shear stress using SPH and visualizes it in a novel particle-based representation. To examine the feasibility and validity of the proposed method, this research designed a series of numerical experiments and validation scenarios under varying test conditions and parameters. The experimental results based on numerical simulations demonstrate the effectiveness and efficiency of proposed method in modeling and simulating bifurcation aneurysm formation and growth. In addition, the results also indicate the feasibility of the proposed wall shear stress simulation and visualization scheme, which enriches the means of blood analysis.

Deciphering the Catalytic Proficiency and Mechanism of the N-Acetylglucosamine Deacetylase From Pantoea dispersa.

Glucosamine (GlcN) is a widely utilized amino monosaccharide. It is traditionally synthesized from N-acetylglucosamine (GlcNAc) via chemical processes that pose environmental threats. In pursuit of a greener alternative, our investigation explored biocatalysis with a Pantoea dispersa derived deacetylase (Pd-nagA), showcasing its efficacy as a catalyst in GlcN production. As a result, this work provides a comprehensive characterization of Pd-nagA, scrutinizes its enzymatic behavior, and delves into the deacetylation mechanism in detail. Heterologous expression methods were utilized for the production and isolation of Pd-nagA, followed by a kinetic evaluation highlighting its enzymatic activity. The complex interactions between the enzyme and its substrate were investigated by integrating classical molecular dynamics, quantum mechanics/molecular mechanics simulations, funnel metadynamics, and on-the-fly probability enhanced sampling techniques, thereby elucidating the precise deacetylation pathway. Rigorous computational analysis results demonstrated that Pd-nagA exhibited promising specificity and efficiency for GlcNAc with a high turnover rate. The catalytic residues central to the reaction were identified, and the underlying quantum reaction mechanism was detailed. Our findings suggest an approach to GlcN production using eco-friendly biocatalysis, positioning Pd-nagA at the forefront of industrial application not only because of its remarkable catalytic capabilities but also due to its potential for enzyme optimization.