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21.
《Advanced Powder Technology》2023,34(6):104028
The Collisional-SPH method models the combined evolution of deformation and frictional contact forces in elastoplastic granular collisions. However, there are many applications in which the granules are not spherical. In this paper, CSPH is extended to model an impact of an ellipsoidal granule on a flat deformable substrate. The CSPH spring-stiffness formulation is developed to account for the contact area eccentricity. Validation for different granule orientations and aspect-ratios are presented. The combined effect of substrate deformation and non-spherical granule shape on the contact-zone mechanics is investigated for different granule orientations and aspect ratios. It is found that the granule’s orientation and aspect ratio influences the interdependence between substrate deformation and contact-force distribution and should be accounted for in collision models. 相似文献
22.
甄莹;曹宇光;张振永;白芳;钮瑞艳 《石油学报》2024,45(7):1130-1140
为解决现有流固耦合模型建模难度高、计算效率低而无法广泛用于CO2管道裂纹扩展预测的问题,提出了一种基于减压模型的管土耦合作用下CO2管道裂纹动态扩展模拟方法。在该方法中管道断裂与流体减压间复杂的流固耦合作用由基于爆破实验及模拟所得压力数据提出的CO2三维减压模型结合加载子程序代替实现,大变形下管土耦合关系采用光滑粒子流方法描述。为验证所构建数值模拟方法的可靠性,将其用于再现管道爆破实验,同时基于该方法对半回填、无回填及完全回填状态下CO2管道韧性断裂行为进行了对比研究。结果表明,所提出的模拟方法较为可靠,两种工况下裂纹扩展速度模拟值与实验值误差分别为21.6 % 与7.6 % ,证明所构建的减压模型可有效描述裂纹扩展过程中管内压力时空演化规律,同时可避免对复杂流固耦合问题的求解,为后续超临界CO2管道断裂行为参数化研究及止裂预测模型的构建奠定了基础。研究结果表明,土壤回填效应对管道裂纹扩展长度、速度、管道整体变形等断裂行为影响显著,相较于无回填管道,完全回填管道裂纹扩展速度下降了19 m/s,且管道变形受到明显限制,有利于裂纹止裂。 相似文献
23.
I Made Wiragunarsa;Lavi Rizki Zuhal;Tatacipta Dirgantara;Ichsan Setya Putra; 《International journal for numerical methods in engineering》2024,125(7):e7431
Total Lagrangian SPH (TLSPH) offers many advantages that can overcome instability and computational time issues. However, it is not naturally applicable to problems with contact. Many problems in solid dynamics and structural analysis require contact definition. In order to use the total Lagrangian formulation, further development for the contact algorithm is required. This research proposes an algorithm to implement inter-particle contact in TLSPH using an adaptive hybrid-kernel scheme for the first time. A combination of the updated and total Lagrangian formulations at the contact surface is introduced, in which the kernel type change automatically when particles from a different body are detected. In kernel change from the updated to the total Lagrangian formulation, the gradient correction cannot be performed using a common correction method because different frames of reference are used. Therefore, a hybrid-kernel correction technique is proposed to maintain the zeroth- and first-order completeness. Then, the contact force is obtained from the inter-particle force using the conservation of momentum. The proposed method does not require a user-defined parameter that makes the application straightforward. Based on the test, the proposed method agrees well with the data available in published literature and the finite element method. Compared with the contact method in classical SPH, the proposed TLSPH shows a significant stability improvement. 相似文献
24.
C. Huang D. H. Zhang Y. X. Shi Y. L. Si B. Huang 《International journal for numerical methods in engineering》2018,113(2):179-207
The conventional SPH method has been frustrated with the low accuracy originated from the particle inconsistency. The finite particle method (FPM) is an improved SPH method with a higher‐order accuracy. However, the numerical accuracy and stability of FPM depend on the uniformity of particles. Facing the disorder particles, the conventional FPM may suffer from an ill‐conditioned corrective matrix and is difficult to conduct longtime simulations. A popular and robust particle regularization scheme is the so‐called particle shifting technology (PST), which can effectively enhance the accuracy and stability of particle methods. In the context of FPM, PST is analyzed and discussed, and a modified PST (MPST) is proposed. Modified PST saves great amount of computational cost with respect to the conventional PST and acquires better features of accuracy and stability. Finally, the coupled FPM method by combining MPST and δ‐SPH is developed to simulate a series of viscous flows. The numerical results indicate that MPST is effective in improving accuracy, stability, and efficiency of PST, and the coupled FPM is shown to be robust for simulating viscous flows and has a higher accuracy and stability. 相似文献
25.
Micro ultrasonic machining (micro-USM) is an unconventional micromachining technology that has capability to fabricate high aspect ratio micro-holes, intricate shapes and features on various hard and brittle materials. The material removal in USM is based on brittle fracture of work materials. The mechanical properties and fracture behaviour are different for varied hard and brittle materials, which would make a big difference in the processing capability of micro-USM. To study the processing capability of USM and exploit its potential, the material removal of work materials, wear of abrasive particles and wear of machining tools in USM of three typical hard and brittle materials including float glass, alumina, and silicon carbide were investigated in this work. Both smoothed particle hydrodynamics (SPH) simulations and verification experiments were conducted. The material removal rate is found to decrease in the order of glass, alumina, and silicon carbide, which can be well explained by the simulation results that cracking of glass is faster and larger compared to the other materials. Correspondingly, the tool wear rate also dropped significantly thanks to the faster material removal, and a formation of concavity on the tool tip center due to intensive wear was prevented. The SPH model is proved useful for studying USM of different hard and brittle materials, and capable of predicting the machining performance. 相似文献
26.
受全球气候变暖的影响,由极端天气引发的类似溃坝等问题发生的概率大大增加,深入研究溃坝水流的水动力特性势在必行。在分析光滑粒子流体动力学基本原理的基础上,提出了一种改进的边界处理方法,即将接近壁面的流体视为层流,在耦合动力边界附近引入层流黏性近似边界层理论。采用该方法对溃坝水流进行数值模拟,将SPH数值模拟得到的外轮廓、自由液面高度以及压力与实验结果进行了比较和分析。结果表明:改进的边界处理方法较完整地得到了水流与壁面相互作用而产生的多种复杂的物理现象,其外部轮廓与实验非常吻合;自由表面融合过程中液面间冲击的能量耗散会导致融合后的液面高度存在一些差异;不同监测点处压力随时间的变化基本落在置信区间之内。数值模拟结果与实验结果吻合度较高,验证了改进方案的可靠性和计算结果的准确性。 相似文献
27.
《Advanced Powder Technology》2019,30(12):2997-3009
During screening, a liquid stream, besides the vibration, can be applied for the acceleration of the separation. The discrete element method coupled with the smoothed particle hydrodynamics (DEM-SPH) is used to numerically analyse wet continuous screening here. Within the applied DEM-SPH a new simple model for the representation of the screening surface is suggested in this study. In this model, the influence of the screening surface on the fluid is represented using external forces, which act on the SPH particles in close vicinity of the screen. A required validation of the DEM-SPH method for the analysis of a vibrated particle-laden system is performed by comparing obtained DEM-SPH results with the results derived using the DEM coupled with finite volume method. The performed simulations of dry and wet continuous screening demonstrate that flowing water, in most simulated cases, accelerates the separation of particles. The presented study demonstrates the potential of the coupled DEM-SPH method for the analysis of wet screening processes. To our best knowledge, the simulation of wet screening using a two-way coupled numerical DEM-SPH approach not resolving the flow around individual particles is demonstrated in the scientific literature for the first time. 相似文献
28.
29.
基于SPH结合FEM的喷丸残余应力数值模拟 总被引:1,自引:0,他引:1
针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐标进行随机化处理,形成了大量丸粒冲击工件表面的随机喷丸仿真模型。通过分析确定了喷丸饱和时间,研究了喷射角度、弹丸流量对残余应力场的影响。结果表明:在喷丸参数一定的条件下,存在相应的饱和喷丸时间;研究喷丸参数对残余应力的影响时,应在喷丸达到饱和时间之后提取残余应力值;喷射角度增大,残余压应力增大;开始时弹丸流量增大,残余压应力会有所增大,但当其达到饱和值后,残余压应力不再变化。 相似文献
30.
This study aims to numerically and experimentally investigate the response of a medium strength rock material under unconfined compression loading up to failure. The unconfined compressive strength (UCS) is one of the most important parameters in characterising rock material behaviour. Hence the UCS is crucial in understanding the failure mechanism of fractured rocks. An effective approach to determine the UCS and to investigate the behaviours of rock materials under unconfined compression is essential in the majority of research fields of rock mechanics. The experimental configuration for the unconfined compression test, suggested by the protocols of the ASTM standard, has some limitations which affect the accuracy in determination of the real UCS. Among several alternative configurations proposed, the Mogi's configuration seems to be the most appropriate one. Therefore, the ASTM and Mogi's configurations were used to perform the tests on a medium strength rock material, i.e. Pietra Serena sandstone. The results using two configurations were discussed in terms of the differences. The tests were also replicated in LS-DYNA using a finite element method (FEM) coupled smooth particle hydrodynamics (SPH) technique. This technique is employed in this study due to its capabilities to cope with large deformation issues related to the rocks. An advanced material model, called the Karagozian and Case Concrete (KCC) model, is implemented in the numerical simulations. The KCC model consists of three independent fixed failure surfaces and it can consider the damage accumulation based on the current state of stress among these failure surfaces. An equation-of-state (EOS) is used in conjunction with KCC material model for decoupling the volumetric and deviatoric responses. The numerical and experimental results were finally compared with the focus on the stress–strain diagram and the failure patterns. The comparison shows that the numerical results are in good agreement with the experimental results. 相似文献