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Investigation of droplet collision characteristics with moving film and its comparison with stationary film: unsteady and 3D CLSVOF method 研究液滴与运动薄膜的碰撞特性及其与静止薄膜的比较:非稳态和三维 CLSVOF 方法
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-17 DOI: 10.1007/s11012-024-01878-z
Pouyan Adibi, Seyed Ahmad Kamalnadian, Kazem Mohammadzadeh

This research deals with a numerical study of a drop impacting a moving film as a transient three-dimensional and its comparison with static film. For the modeling, the CLSVOF (Coupled Level Set and Volume of Fluid) method has been used for drop impact analysis. The parametric effects of film Reynolds number (830 < Ref < 4478), non-dimensional film thickness (0.25 < h* < 0.75), drop Weber number (249 < We < 1762), non-dimensional time (0.5 < τ < 4.0), and impact angle (0°, 30°, and 60°), on the interface evolution, was investigated. Further, the results have been compared to drop-impacting static film obtained by previous researchers, whereby in most cases consists of the results with drop-impacting static film have been observed. However, the drop impacting the moving film indicated a different behavior in some cases because of the unique effect of the moving film movement. Doubling the film velocity as well as a 57% reduction in the drop velocity, caused an 8.3% and 6.66% increase in the crown asymmetry and suppression of the downstream crown. The crown slip toward the downstream flow was observed in all cases. Doubling the fluid film velocity, on average, reduced the crown height by 18.5% and increased its diameter by 10.48%. However, its effect on the crater diameter was negligible (1%). An increase in the film thickness from 0.5 mm to 1 mm (h* from 0.25 to 0.5), fed the upstream crown, and on average, increased its height by 10.57%. At a low impact velocity of 3 m/s (We = 249), the crown diameter was, on average, 26.7% larger than its diameter at the velocity of 7 m/s (We = 1358). By increasing the drop impact angle to 60 degrees and overcoming the effect of the fluid film velocity, the crown behavior was the same as its behavior with the drop impact on the static film. Finally, to predict the upstream crown height, downstream crown height, crown diameter, and crater diameter, four novel five-variable correlations (depending on τ, θ, Ref, We, and h*) are developed. It is concluded that a good agreement exists between the numerical data, and correlation results.

本研究涉及液滴撞击运动薄膜的瞬态三维数值研究及其与静态薄膜的比较。在建模过程中,采用了 CLSVOF(液位和流体体积耦合)方法进行液滴冲击分析。研究了薄膜雷诺数(830 < Ref < 4478)、非维薄膜厚度(0.25 < h* < 0.75)、液滴韦伯数(249 < We < 1762)、非维时间(0.5 < τ < 4.0)和冲击角(0°、30° 和 60°)对界面演变的参数影响。此外,还将研究结果与之前研究人员获得的液滴撞击静态薄膜的结果进行了比较,在大多数情况下,观察到的结果与液滴撞击静态薄膜的结果一致。然而,由于移动薄膜运动的独特效果,液滴撞击移动薄膜在某些情况下显示出不同的行为。将薄膜速度提高一倍以及将液滴速度降低 57%,分别导致了 8.3% 和 6.66% 的树冠不对称和下游树冠的抑制。在所有情况下,都观察到树冠向下游流动方向滑移。将流膜速度增加一倍,平均可使冠高度降低 18.5%,直径增加 10.48%。然而,它对火山口直径的影响可以忽略不计(1%)。流体膜厚度从 0.5 毫米增加到 1 毫米(h* 从 0.25 增加到 0.5),为上游岩冠提供了动力,平均增加了 10.57% 的高度。在 3 米/秒(We = 249)的低冲击速度下,树冠直径比 7 米/秒(We = 1358)时的直径平均大 26.7%。通过将液滴撞击角增大到 60 度并克服流体膜速度的影响,水冠的行为与液滴撞击静态膜时的行为相同。最后,为了预测上游树冠高度、下游树冠高度、树冠直径和凹坑直径,建立了四种新的五变量相关关系(取决于 τ、θ、Ref、We 和 h*)。结论是数值数据与相关结果之间存在良好的一致性。
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引用次数: 0
Compound control method for reliability of the robotic arms with clearance joint 提高带间隙接头机械臂可靠性的复合控制方法
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-16 DOI: 10.1007/s11012-024-01881-4
Yaodong Fu, Xiuting Sun, Zigen Song, Jian Xu

This study provides a reliability improvement control method for robotic arms with clearance joints. Firstly, the dynamical model of a six-DOF robotic arm with joint clearance is established, and the Archard model is utilized to describe joint wear, considering its effect on clearance evolution. The kinematic and dynamic characteristics of the robotic arm with clearances are analyzed concerning the contact and operation state variations. Then, the influence of clearance wear on the operational reliability of the robotic arm is studied as joint wear in the robotic arm contains interval uncertainty. To provide the uncertainty factors caused by the interval, we introduce Chebyshev functions to describe the dynamic response uncertainty and reliability. The non-probabilistic reliability index is given to evaluate the reliability of the robotic arm based on the stress intensity interference theory. Lastly, to improve operational accuracy and reliability, a novel compound control strategy containing collision force feedforward and PD feedback is carried out. It is compared with the traditional PD control strategy. Also, the sensitivity and robustness of the proposed compound control strategies are discussed. The results show that the proposed control strategy can effectively enhance the dynamics precision and reliability of the robotic arm, with satisfactory robustness. This study provides the control method for joint-worn robotic arms with undesired joint clearance, having significant potential applications for guaranteeing mission reliability in the fields of aerospace and industrial robotics.

本研究为具有间隙关节的机械臂提供了一种提高可靠性的控制方法。首先,建立了带关节间隙的六自由度机械臂动力学模型,并利用 Archard 模型描述关节磨损,同时考虑其对间隙演变的影响。分析了带有间隙的机械臂在接触和运行状态变化方面的运动学和动力学特性。然后,研究了间隙磨损对机械臂运行可靠性的影响,因为机械臂中的关节磨损包含间隔不确定性。为了提供由间隙引起的不确定性因素,我们引入了切比雪夫函数来描述动态响应的不确定性和可靠性。基于应力强度干涉理论,我们给出了非概率可靠性指数来评估机械臂的可靠性。最后,为了提高操作精度和可靠性,采用了一种包含碰撞力前馈和 PD 反馈的新型复合控制策略。它与传统的 PD 控制策略进行了比较。此外,还讨论了所提出的复合控制策略的灵敏度和鲁棒性。结果表明,所提出的控制策略能有效提高机械臂的动力学精度和可靠性,并具有令人满意的鲁棒性。这项研究为具有非期望关节间隙的关节磨损机械臂提供了控制方法,在保证航空航天和工业机器人领域任务的可靠性方面具有重要的潜在应用价值。
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引用次数: 0
Multiscale topology optimization of anisotropic multilayer periodic structures based on the isogeometric analysis method 基于等几何分析方法的各向异性多层周期结构的多尺度拓扑优化
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-14 DOI: 10.1007/s11012-024-01873-4
Jianping Zhang, Jiahong Chen, Jiangpeng Peng, Yi Qiu, Zhijian Zuo, Zhiqiang Zhang

A multiscale topology optimization model of anisotropic multilayer periodic structures (MPS) is proposed using the isogeometric analysis (IGA) method. The integrative design of multiscale structures was realized in two stages: the distribution optimization of multilayer periodic materials, which determines the types, distribution, and volume fraction of microstructures, and parallel topology optimization, which optimizes the macrostructure and various microstructures simultaneously. To implement the multilayer periodic constraint, the relative density and sensitivity of the IGA control points were equally redistributed. The correctness and advantages of the proposed model were confirmed by comparing its results with those obtained using finite element methods, and the optimal IGA microstructures displayed smoother boundaries. In addition, the multiscale MPS of the cantilever was 3D printed, confirming the practicality of the proposed model. The influences of the regularization scheme, multilayer periodic constraints, and Poisson's ratio factor on the results of the multiscale multilayer periodic optimization were explored, and recommendations for proper values of these parameters were provided to enhance the structural stiffness.

利用等几何分析(IGA)方法提出了各向异性多层周期结构(MPS)的多尺度拓扑优化模型。多尺度结构的综合设计分两个阶段实现:一是多层周期材料分布优化,即确定微结构的类型、分布和体积分数;二是并行拓扑优化,即同时优化宏观结构和各种微结构。为了实现多层周期约束,IGA 控制点的相对密度和灵敏度被平均重新分配。通过与使用有限元方法得出的结果进行比较,证实了所提模型的正确性和优势,而且优化的 IGA 微结构显示出更平滑的边界。此外,悬臂的多尺度 MPS 已实现 3D 打印,证实了所提模型的实用性。研究还探讨了正则化方案、多层周期约束和泊松比系数对多尺度多层周期优化结果的影响,并就这些参数的适当取值提出了建议,以增强结构刚度。
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引用次数: 0
CFD and ray tracing analysis of a discrete nozzle for laser metal deposition 用于激光金属沉积的离散喷嘴的 CFD 和射线追踪分析
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-10 DOI: 10.1007/s11012-024-01876-1
Jon Lambarri, Jon Gabirondo-López, Telmo Echániz, Silvio Schmalfuß, Maria José Tobar

Blown powder laser metal deposition (p-LMD) is an advanced additive manufacturing technique that creates metal components by fusing metal powder particles with a substrate using a high-power laser source. This study explores the interactions between laser energy, powder flow, and gas dynamics within a three-channel nozzle configuration for a p-LMD processes, using an innovative three-step CFD–ray tracing model. Experimental techniques, including scanning electron microscopy for powder characterisation, radiometry for emissivity calibration, Pitot tube anemometry for gas flow velocity, and particle image velocimetry for particle velocity measurements, calibrate and validate the model. Employing ray tracing, the study evaluates the consequences of reflected and scattered light on the effective laser field seen by the powder cloud during the LMD process. Significant findings include the identification of optimal gas flow rates for effective shielding of the interaction volume and the impact of varying mass flow rates on laser beam attenuation and particle heating.

吹粉激光金属沉积(p-LMD)是一种先进的增材制造技术,它通过使用高功率激光源将金属粉末颗粒与基体熔化来制造金属部件。本研究采用创新的三步 CFD 射线跟踪模型,探索了 p-LMD 过程中三通道喷嘴配置内激光能量、粉末流动和气体动力学之间的相互作用。实验技术包括用于粉末特征描述的扫描电子显微镜、用于发射率校准的辐射测量法、用于气体流速测量的皮托管风速测量法和用于颗粒速度测量的颗粒图像测速法,这些技术对模型进行了校准和验证。该研究采用光线追踪技术,评估了在 LMD 过程中反射光和散射光对粉末云所见有效激光场的影响。重要发现包括确定了对相互作用体积进行有效屏蔽的最佳气体流速,以及不同质量流量对激光束衰减和粒子加热的影响。
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引用次数: 0
Design and performance investigation of a sliding-mode adaptive proportional–integral–derivative control for cable-breakage scenario 针对电缆断裂情况的滑动模式自适应比例-积分-派生控制的设计与性能研究
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-09 DOI: 10.1007/s11012-024-01875-2
Vincenzo Di Paola, Stéphane Caro, Matteo Zoppi

Controlling a cable-driven parallel robot (CDPR) when a cable breaks is challenging. In this paper, a sliding mode adaptive PID control is designed to ensure a safe guidance of the load when a cable fails. Indeed, regardless when a cable breaks, this control makes it possible enchanting the guidance of the load inside the remaining wrench feasible workspace. In other words, it allows reducing the load oscillation and then increasing the safety of the recovery manoeuvre. Performances are evaluated through simulations by considering a spatial CDPR and comparing the results with a PID control.

在电缆断裂时控制电缆驱动并联机器人(CDPR)是一项挑战。本文设计了一种滑动模式自适应 PID 控制,以确保电缆断裂时负载的安全引导。事实上,无论电缆何时断裂,该控制都能在剩余的扳手可行工作空间内引导负载。换句话说,它可以减少负载的摆动,从而提高恢复操作的安全性。通过考虑空间 CDPR 并将结果与 PID 控制进行比较,对性能进行了模拟评估。
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引用次数: 0
Theoretical calculation methods of stable bearing capacity for thin-walled shells with corrosion and variable temperature 腐蚀和变温薄壁壳体稳定承载力的理论计算方法
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-09-02 DOI: 10.1007/s11012-024-01811-4
Cheng Huijuan Liu, Giuseppe Lacidogna

Thin-wall shells (steel plates, steel cylindrical shells, steel spherical shells, etc.) are widely used in many engineering fields such as construction, machinery, chemical industry, navigation, and aviation because of their light weight and high strength. Their failure modes under static pressure or impact dynamic load are mostly buckling instability, and the failure is very sudden, often causing structural failure or even catastrophic accidents without obvious symptoms. In this framework, the significance of this paper is that it considers the influence of external environment corrosion on steel shells' bearing capacity using plate and shell classical stability theory, and investigates the stable bearing capacity of thin-wall steel shells in view of corrosion impact. By this approach, a theoretical calculating method for the time-varying stable bearing capacity of plate and shell thin-walled steel members under the simultaneous action of corrosion and temperature changes is obtained, providing a useful theory for complex engineering practices such as corrosion and temperature changes, including fire actions. Noted that for this method with no analytical solution found, its numerical solutions are given in the appendixes.

薄壁壳体(钢板、钢制圆柱形壳体、钢制球形壳体等)由于重量轻、强度高,被广泛应用于建筑、机械、化工、航海、航空等众多工程领域。它们在静压或冲击动载荷作用下的失效模式多为屈曲失稳,且失效非常突然,往往在没有明显症状的情况下造成结构失效甚至灾难性事故。在此框架下,本文的意义在于利用板壳经典稳定理论,考虑外部环境腐蚀对钢壳承载能力的影响,研究腐蚀影响下薄壁钢壳的稳定承载能力。通过这种方法,获得了板壳薄壁钢构件在腐蚀和温度变化同时作用下的时变稳定承载力理论计算方法,为腐蚀和温度变化等复杂工程实践(包括火灾行动)提供了有用的理论。注意到对于未找到解析解的该方法,其数值解在附录中给出。
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引用次数: 0
Network-based and sheet-based Gyroid lattice structures with different gradient directions: manufacture, mechanical response and energy absorption 具有不同梯度方向的网状和片状 Gyroid 晶格结构:制造、机械响应和能量吸收
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-08-31 DOI: 10.1007/s11012-024-01874-3
Bo Hao, Zhiming Zhu, Li Zhang

To investigate the effect of gradient direction on mechanical properties and energy absorption capability of Gyroid lattice structures (GLSs), network-based and sheet-based lattice structures (G1-N768, G2-N768, G1-S768, G2-S768) of different gradient directions with an average porosity of 70% were established. The Al-Si10-Mg samples were manufactured through selective laser melting (SLM). Through compression tests and finite element analysis (FEA), the energy absorption, deformation behavior, and mechanical properties of the GLSs were evaluated. The data exhibited good consistency, and the deviations of yield strength, elastic modulus, plateau stress, densification strain and energy absorption could be controlled at about 10%. The results indicated that whether it is network-based or sheet-based GLSs, by changing the gradient direction, the deformation behavior could be transformed from layer-by-layer deformation (G1-GLSs) to uniform deformation (G2-GLSs), and thus realize the regulation of mechanical properties. At the same time, due to different topological configurations, stretch-dominated sheet-based GLSs (G1-S768, G2-S768) exhibited higher energy absorption capability and mechanical properties than bending-dominated network-based GLSs (G1-N768, G2-N768), and the energy absorption, yield strength and elastic modulus increased by 93.7%, 80.8% and 66.7%, respectively. In addition, the introduction of the Johnson–Cook model has effectively simulated the failure behavior of GLSs. This paper can offer theoretical guidance for the subsequent performance regulation and application of functionally graded GLSs.

为了研究梯度方向对Gyroid晶格结构(GLSs)机械性能和能量吸收能力的影响,我们建立了不同梯度方向的网状和片状晶格结构(G1-N768、G2-N768、G1-S768、G2-S768),其平均孔隙率为70%。铝-硅-10-镁样品是通过选择性激光熔融(SLM)制造的。通过压缩试验和有限元分析,对 GLS 的能量吸收、变形行为和机械性能进行了评估。数据显示出良好的一致性,屈服强度、弹性模量、高原应力、致密化应变和能量吸收的偏差均可控制在 10% 左右。结果表明,无论是网状 GLS 还是片状 GLS,通过改变梯度方向,都可以将变形行为从逐层变形(G1-GLS)转变为均匀变形(G2-GLS),从而实现对力学性能的调控。同时,由于拓扑结构的不同,拉伸为主的片状 GLS(G1-S768、G2-S768)比弯曲为主的网状 GLS(G1-N768、G2-N768)具有更高的能量吸收能力和力学性能,能量吸收率、屈服强度和弹性模量分别提高了 93.7%、80.8% 和 66.7%。此外,Johnson-Cook 模型的引入还有效地模拟了 GLS 的失效行为。本文可为功能分级 GLS 的后续性能调节和应用提供理论指导。
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引用次数: 0
Eccentric contraction response of stimulated skeletal muscle fascicle at the various strain rates and stimulation timing 不同应变率和刺激时间下受刺激骨骼肌筋膜的偏心收缩反应
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-08-30 DOI: 10.1007/s11012-024-01872-5
Dat Trong Tran, Liren Tsai

Muscle injuries are the most common sports injuries in eccentric contraction. There are many factors that could influence the severity of muscle injuries, including strain, strain rate and stimulation. This study evaluated the interaction of these factors on the biomechanical properties of the muscle–tendon bundle and their role in injuries. A Hopkinson bar system, an MTS machine and an electrical pulse generator were utilized to collect eccentric contraction response data of over 150 frog muscle–tendon samples at strain rates ranging from 0.01 to 300 s−1. The results have shown that the maximum eccentric stress has increased and peaked at the strain rate of about 150 s−1. That peak value has then maintained at the following strain rates. In contrast, Young’s modulus reduced as the strain rate changed from 50 to 300 s−1. That trend was in contrast to unstimulated muscle bundles. In addition, strain rate has significantly influenced stimulated tendon–muscle bundle fracture. Samples tend to rupture at a minor strain of about 3.5% with strain rates over 200 s−1. Because of the increasing stiffness of the muscle area at high strain rates, increased strain in the tendon region resulted in frequent injuries in the tendon area. On the other hand, a maximum stress reduction was detected when the muscle bundles were stimulated at muscle strain greater than 0.2. The results showed that improper timing of stimulation could increase muscle injury. The study shows that the stimulation and strain rate dramatically impact muscle–tendon properties and the risk of injury.

肌肉损伤是偏心收缩运动中最常见的运动损伤。影响肌肉损伤严重程度的因素有很多,包括应变、应变率和刺激。本研究评估了这些因素对肌肉-肌腱束生物力学特性的相互作用及其在损伤中的作用。研究人员利用霍普金森棒系统、MTS 机和电脉冲发生器收集了 150 多个蛙类肌肉-肌腱样本在 0.01 至 300 s-1 应变速率下的偏心收缩响应数据。结果显示,最大偏心应力在应变率约为 150 s-1 时增加并达到峰值。在随后的应变速率下,该峰值一直保持不变。相反,当应变速率从 50 s-1 变为 300 s-1 时,杨氏模量降低。这一趋势与未受刺激的肌肉束相反。此外,应变速率对刺激肌腱-肌束断裂有显著影响。应变速率超过 200 s-1 时,样本往往会在约 3.5% 的小应变下断裂。由于在高应变率下肌肉区域的硬度增加,肌腱区域的应变增加导致肌腱区域频繁受伤。另一方面,当肌肉应变大于 0.2 时刺激肌束,可检测到最大应力降低。结果表明,刺激时机不当会增加肌肉损伤。这项研究表明,刺激和应变率会极大地影响肌肉肌腱的特性和受伤风险。
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引用次数: 0
A continuum model for in-plane analysis of masonry: an approach based on failure mode classification 砌体平面分析连续体模型:基于失效模式分类的方法
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-08-30 DOI: 10.1007/s11012-024-01864-5
G. Bertani, L. Patruno, A. M. D’Altri, G. Castellazzi, M. Cervera, S. de Miranda

In this paper, a multi-failure continuum model for in-plane analysis of masonry structures is introduced. The model is based on a recently-proposed single-surface multi-failure strength domain, and is here implemented in an elasto-plastic framework to perform nonlinear incremental static analyses on masonry walls. As a key feature of the model, the activated failure mechanism(s) can be identified and the corresponding plastic strains evolution computed. In particular, the distinction between crushing failure, joint failure (horizontal, vertical, and diagonal) and mixed joint-block failure is guaranteed by means of specific weights assigned to each failure mode. This amounts to a classification procedure which selects the active failure modes based on the information provided by the stress state. As a further novelty of this work, ad hoc nonassociated flow rules are then chosen to characterize each failure mode independently, so allowing a straightforward tracking of their nonlinear evolution. Well-known numerical examples are used to show the capability of the approach. From these, the proposed continuum model appears accurate and the tracking of the plastic strains related to the considered failure modes allows a straightforward interpretation of the results.

本文介绍了一种用于砌体结构平面分析的多失效连续模型。该模型以最近提出的单面多破坏强度域为基础,在弹塑性框架内实施,对砌体墙进行非线性增量静力分析。该模型的一个主要特点是,可以识别激活的破坏机制,并计算相应的塑性应变演变。特别是,通过为每种失效模式分配特定权重,可确保区分挤压失效、接缝失效(水平、垂直和对角线)和接缝-块体混合失效。这相当于一种分类程序,可根据应力状态提供的信息选择有效的失效模式。作为这项工作的另一个新颖之处,还选择了特别的非关联流动规则来独立描述每种失效模式,从而可以直接跟踪它们的非线性演变。我们使用著名的数值实例来展示这种方法的能力。从这些例子中可以看出,所提出的连续体模型是准确的,对与所考虑的失效模式相关的塑性应变的跟踪可以直接解释结果。
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引用次数: 0
Navigating speed–accuracy trade-offs for multi-physics simulations 多物理场仿真的速度-精度权衡导航
IF 2.7 3区 工程技术 Q3 MECHANICS Pub Date : 2024-08-25 DOI: 10.1007/s11012-024-01867-2
Zohreh Moradinia, Hans Vandierendonck, Adrian Murphy

This paper introduces a novel approach aimed at addressing persistent challenges inherent in conventional multiphysics modeling methodologies. Existing techniques, such as numerical modeling and analytical calculations, often suffer from time-consuming and computationally intensive processes, leading to inefficiencies, particularly in intricate simulations. The proposed methodology employs regression machine learning algorithms as a black-box solution to anticipate errors and execution times in multiphysics simulations. Diverging from conventional methods, this approach streamlines the exploration of simulation options, providing discernible choices for balancing speed and precision. The efficacy of the methodology is exemplified through successful applications to heat transfer and fluid–structure interaction problems, illustrating its adaptability across diverse scenarios. Notably, the approach upholds the integrity of physics equations and simulation convergence while markedly reducing the trial-and-error efforts and computational burdens associated with traditional methodologies. In summary, the proposed approach emerges as an innovative and promising solution to augment the accuracy, efficiency, and dependability of multiphysics simulations.

本文介绍了一种新方法,旨在解决传统多物理场建模方法中固有的难题。现有的技术,如数值建模和分析计算,往往存在耗时和计算密集的问题,导致效率低下,尤其是在复杂的模拟中。建议的方法采用回归机器学习算法作为黑盒解决方案,以预测多物理场仿真中的错误和执行时间。与传统方法不同的是,这种方法简化了仿真选项的探索,为平衡速度和精度提供了明确的选择。该方法在传热和流固耦合问题上的成功应用充分体现了它的功效,说明了它在各种情况下的适应性。值得注意的是,该方法在保持物理方程完整性和仿真收敛性的同时,显著减少了与传统方法相关的试错工作和计算负担。总之,所提出的方法是一种创新而有前途的解决方案,可提高多物理场仿真的精度、效率和可靠性。
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引用次数: 0
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