Granular Matter最新文献

{"title":"Development of optimal L-PBF process parameters using an accelerated discrete element simulation framework","authors":"Marwan Aarab,&nbsp;Bram J. A. Dorussen,&nbsp;Sandra S. Poelsma,&nbsp;Joris J. C. Remmers","doi":"10.1007/s10035-024-01432-4","DOIUrl":"10.1007/s10035-024-01432-4","url":null,"abstract":"<div><p>Laser Powder Bed Fusion (L-PBF) has immense potential for the production of complex, lightweight, and high-performance components. The traditional optimization of process parameters is costly and time-intensive, due to reliance on experimental approaches. Current numerical analyses often model single-line scans, while it is necessary to model multiple fully scanned layers to optimize for bulk material quality. Here, we introduce a novel approach utilizing discrete element simulations with a ray tracing-modeled laser heat source. Our approach significantly reduces the cost and time consumption compared to conventional optimization methods. GPU acceleration enables efficient simulation of multiple layers, resulting in parameters optimized for bulk material. In a case study, parameters were optimized for AlSi10Mg in just 5 days, a process that would have taken over 8 months without GPU acceleration. Experimental validation affirms the quality of the optimized process parameters, achieving an optical density of 99.91%.</p><h3>Graphical Abstract</h3><p>Optimization using the accelerated simulation yielded an optimized parameter set within 5 days. This resulted in a\u0000part with an optical density of 99.91%.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10035-024-01432-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluctuations and failure in granular materials: theory and numerical simulations","authors":"Luigi La Ragione,&nbsp;Giuseppina Recchia,&nbsp;Felix Darve,&nbsp;Francois Nicot,&nbsp;Antoine Wautier","doi":"10.1007/s10035-024-01431-5","DOIUrl":"10.1007/s10035-024-01431-5","url":null,"abstract":"<div><p>We consider a dense aggregate of elastic, frictional particles isotropically compressed and next uniaxial strained at constant pressure. We show how failure can be predicted if fluctuations in the kinematics of contacting particles are introduced. We focus on the second order work and the possibility that at some stressed states it becomes negative under proper perturbations. Our analysis involves both a theoretical model and numerical simulations based upon the distinct element method (DEM). The theoretical model deals with contacting particles with incremental relative displacements that deviate from the average deformation in order to ensure their equilibrium. Because of this, the macroscopic stiffness tensor of the aggregate, that relates increments in stress with increments in strain, does not have the major symmetry. Consequently, in the hardening regime, we predict stressed states in which the second order work vanishes. The model seems transparent, and it makes clear and illustrative the role played by the fluctuations introduced in the kinematics of contacting particles in relation to the vanishing of second order work in an aggregate of compressed particles. The comparison with numerical simulations data supports the model.</p><h3>Graphical Abstract</h3><p>Statistical representation of the aggregate: conditional average.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10035-024-01431-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141255020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Explicit total Lagrangian material point method with implicit frictional-contact model for soft granular materials","authors":"Saeid Nezamabadi,&nbsp;Farhang Radjai","doi":"10.1007/s10035-024-01438-y","DOIUrl":"10.1007/s10035-024-01438-y","url":null,"abstract":"<div><p>We introduce a novel numerical method for the simulation of soft granular materials, in which the particles can undergo large strains under load without rupture. The proposed approach combines an explicit total Lagrangian formulation of Material Point Method (TLMPM) with the Contact Dynamics (CD) method. The TLMPM resolves particle bulk deformations whereas the CD treats contact interactions between soft particles. The efficiency and accuracy of this approach are illustrated by analyzing diametral compression of a soft circular particle and the compaction of an assembly of soft particles up to very high levels of packing fraction. We show that although the assembly undergoes a jamming transition, the particles continue to rearrange as they get increasingly distorted under load. Interestingly, as the packing fraction increases, a transition occurs to a regime fully governed by particle shape change. The evolution of the global stress as well as the connectivity of the particles as a function of the packing fraction are discussed and a predictive model relating stress to packing fraction beyond jamming transition is proposed.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Method for evaluating modulus evolution of granular materials under dynamic loading","authors":"Lihong Tong,&nbsp;Li Fu,&nbsp;Haibin Ding,&nbsp;Zuxiang Lei,&nbsp;Rui Wang,&nbsp;Changjie Xu,&nbsp;Songyan Li","doi":"10.1007/s10035-024-01434-2","DOIUrl":"10.1007/s10035-024-01434-2","url":null,"abstract":"<div><p>The softening effect has been widely accepted as the fundamental mechanical property of the granular materials, which underlies some specific phenomena such as fluidization during vibration. In this paper, a series of resonance column experiments are performed to observe the modulus softening of granular materials. A statistical softening model is subsequently proposed and its applicability is verified through a quantitative analysis of the variation of the normalized modulus by changing the external confining pressure. The average potential energy in grain contact has been found to be a power-law scaling with grain size. An evolution model is further implemented to account for the experimental findings on the evolution of modulus of the granular system subjected to different confining pressures. The modulus evolution, including softening and recovery, can be captured by the unified evolution model.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div><div><p>Shear modulus evolution</p></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micro and macro mechanical characterization of artificial cemented granular materials","authors":"Abbas Farhat,&nbsp;Li-Hua Luu,&nbsp;Alexis Doghmane,&nbsp;Pablo Cuéllar,&nbsp;Nadia Benahmed,&nbsp;Torsten Wichtmann,&nbsp;Pierre Philippe","doi":"10.1007/s10035-024-01426-2","DOIUrl":"10.1007/s10035-024-01426-2","url":null,"abstract":"<div><p>The focus of this study is the experimental characterization of cemented granular materials, with the aim of identifying the microscopic properties of the solid bonds and describing the extension to macroscopic mechanical strength of cemented samples. We chose to use artificially bonded granular materials, made of glass beads connected by solid paraffin bridges. The results of several sets of laboratory tests at different scales are presented and discussed. Micromechanical tests investigate the yield strength of single solid bonds between particles under traction, shearing, bending and torsion loading, as a function of variations in particle size, surface texture and binder content. Macro-scale tensile tests on cemented samples explore then the scale transition, including influence of confining walls through homothetic variations of the sample size. Despite the large statistical dispersion of the results, it was possible to derive and validate experimentally an analytical expression for micro tensile yield force as a function of the binder content, coordination number and grain diameter. In view of the data, an adhesive bond strength at the contact between bead and solid bond is deduced with very good accuracy and it is even reasonable to assume that the other threshold values (shear force, bending and torsion moments) are simply proportional to the tensile yield, thus providing a comprehensive 3D model of cemented bond. However, the considerable dispersion of the data at the sample scale prevents validation of the extended model for macroscopic yield stress. A final discussion examines the various factors that may explain intrinsic variability. By comparison with other more realistic systems studied in the literature in the context of bio-cementation, our artificial material nevertheless appears suitable for representing a cemented granular material. Being easy to implement, it could thus enable the calibration of discrete cohesion models for simulation of practical applications.</p></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140925722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macro- and micro-mechanical behavior of CSU-LRS-1 lunar soil simulant under true triaxial loading path","authors":"Qixin Wu,&nbsp;Yafei Jia,&nbsp;Hao Wu,&nbsp;Zihao Yuan,&nbsp;Xuhai Tang,&nbsp;Yewei Zheng,&nbsp;Haifeng Zhao","doi":"10.1007/s10035-024-01437-z","DOIUrl":"10.1007/s10035-024-01437-z","url":null,"abstract":"<div><p>In this paper, a series of true triaxial tests with different intermediate principal stress ratios are conducted on both the lunar soil simulant and the sandy soils on earth using the discrete element method. An advanced discrete element servomechanism based on polyhedral specimen configuration is implemented such that true triaxial loading paths can be implemented under low confining pressure without introducing severe stress concentration. The high frictional angle and apparent cohesion of the lunar simulant are captured by employing a highly efficient contact model that fuses rolling resistance and van der Waals forces. The employed micro-scale parameters are calibrated based on the triaxial test results of the CSU-LRS-1 lunar soil simulant. The simulation results show that the lunar soil simulant exhibits lower shear strength with an increasing intermediate principal stress ratio. Generally, although the lunar soil simulant has a greater void ratio than that of sandy soils, the former exhibits significantly stronger shear-induced dilatancy and higher shear strength. The evolution of the load-bearing structure is quantified through a contact-normal-based fabric tensor. The interplay between internal structure evolution and external loadings can well explain the difference in mechanical behavior between lunar soil simulant and sandy soils on earth.</p></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140925673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A viscoelastic bonded particle model to predict rheology and mechanical properties of hydrogel spheres","authors":"Michael Mascara,&nbsp;Chandan Shakya,&nbsp;Stefan Radl,&nbsp;Arno Mayrhofer,&nbsp;Christoph Kloss","doi":"10.1007/s10035-024-01429-z","DOIUrl":"10.1007/s10035-024-01429-z","url":null,"abstract":"<p>The use of hydrogels has exponentially increased in recent years in many fields, such as biology, medicine, pharmaceuticals, agriculture, and more. These materials are so widely used because their mechanical properties change drastically with the different chemical compositions of the constituent polymer chains, making them highly versatile for different applications. We introduce a numerical simulation tool that relies on the Discrete Element Method to reproduce and predict the behavior of hydrogel spheres. We first use a benchmark test, namely an oscillatory compression test on a single hydrogel, to calibrate the model parameters, obtaining a good agreement on the material’s rheological properties. Specifically, we show that the normal modified storage and loss moduli, E’ and E”, obtained in the simulation match the experimental data with a small relative error, around 3%, for E’ and 11% for E”. This result aligns with recent work on numerical modeling of hydrogels, introducing a novel approach with bonded particles and a viscoelastic constitutive relation that can capture a wide range of applications thanks to the higher number of elements. Moreover, we validate the model on a particle-particle compression test by comparing the simulation output with the contact force in the compression direction, again obtaining promising results.</p>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140889145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of basal friction on granular column collapse","authors":"Yucheng Li,&nbsp;Deheng Wei,&nbsp;Ningning Zhang,&nbsp;Raul Fuentes","doi":"10.1007/s10035-024-01436-0","DOIUrl":"10.1007/s10035-024-01436-0","url":null,"abstract":"<div><p>The collapse behaviour of granular materials is influenced by many factors, such as aspect ratio and inter-particle friction. However, the specific impact of basal to grain friction on column collapse remains poorly understood. In this study, we systematically analyse the effect of basal friction on gravity-driven granular column collapse using a validated smoothed particle hydrodynamics (SPH) model. The results show that such the basal friction coefficient does influence deposit geometry, deposit morphology, and energy conversion. To predict the run-out distance, we propose a modified formula that incorporates the basal friction coefficient, considering two extreme cases, i.e., <i>μ</i> = 0 and + ∞. The basal friction also exerts an influence on the final height, with higher friction coefficients resulting in greater final heights. As the friction coefficient increases, the aspect ratio corresponding to the maximum final height also increase. However, we observe a convergence of the effect of basal friction on the final height when <i>μ</i> &gt; 0.5. Furthermore, the competition mechanism between the initial column aspect ratio and basal friction coefficient reveals two transition zones between the three main deposit regimes (regime I, regime II, and regime III). This suggests that the deposit regime can be influenced by basal friction. Additionally, an analysis of energy conversion supports many of the conclusions provided in the text and exhibits the interplay between pressure gradient and base friction. Our findings show the clear influence of basal friction on the collapse behaviour of granular materials and therefore should be carefully considered in future studies.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140828570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on modified pre-disintegrated carbonaceous mudstone triaxial test and binary medium model","authors":"Hong-yuan Fu,&nbsp;Hai-tao Yang,&nbsp;Hao Wu,&nbsp;Ling Zeng,&nbsp;Er-lu Wu,&nbsp;Yan Wang","doi":"10.1007/s10035-024-01435-1","DOIUrl":"10.1007/s10035-024-01435-1","url":null,"abstract":"<div><p>In order to eliminate the undesirable characteristics of carbonaceous mudstone roadbed fillers, cement and fly ash are used to modify the pre-disintegrated carbonaceous mudstone, and the stress–strain relationship of pre-disintegrated carbonaceous mudstone before and after modification are analyzed by a series of conventional unconsolidated undrained triaxial compression tests at different confining pressures and different ages. Based on the microscopic modification mechanism of carbonaceous mudstone and the concept of binary medium model, the products from hydration reaction of pre-disintegrated carbonaceous mudstone, cement, and fly ash are regarded as bonded elements, and the pre-disintegrated carbonaceous mudstones without hydration reaction are regarded as frictional elements, and the binary medium model of modified pre-disintegrated carbonaceous mudstone is established. The results show that the stress–strain curve of pre-disintegrated carbonaceous mudstone is strain-hardening type, and the stress–strain of pre-disintegrated carbonaceous mudstone modified by fly ash and cement is strain-softening type, and the mechanical properties of modified pre-disintegrated carbonaceous mudstone are significantly improved. The deformation and damage mechanism of modified carbonaceous mudstone is investigated by applying the concept of binary medium model from a mesoscopic perspective, and the stress-bearing mechanism of bonded elements and frictional elements in external loading and stressing processes are analyzed. Finally, the measured data reveals that the binary medium model can simulate both the stress–strain softening characteristics of modified pre-disintegrated carbonaceous mudstone and the stress–strain hardening characteristics of organic material-modified expansive soils reasonably well.</p></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140810532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A network-based investigation on static liquefaction of sheared granular materials","authors":"Wanda Cao,&nbsp;Jiangzhou Mei,&nbsp;Xiaojuan Yang,&nbsp;Wei Zhou,&nbsp;Xiaolin Chang,&nbsp;Gang Ma","doi":"10.1007/s10035-024-01433-3","DOIUrl":"10.1007/s10035-024-01433-3","url":null,"abstract":"<div><p>Granular materials may undergo static liquefaction under undrained shearing, which is related to many natural hazards, such as landslides. Despite great efforts, the overall process of static liquefaction remains largely unclear. Numerical undrained shear tests on granular assemblies are performed using the discrete element method, and network-based methods are introduced to investigate the evolution of the contact network. The occurrence of static liquefaction is attributed to the collapse of the contact network induced by contact loss. The weak subnetwork is broken before reaching the liquefaction point, while the strong contact subnetwork remains relatively unchanged. The failure of the strong subnetwork is further investigated by the mechanical features of two important mesoscopic structures, namely force chains and contact loops. The buckling events with buckling ratio exceeding the envelope line and the transition from small loops to large loops significantly destroy the stability of force chains, which causes the failure of force chains and eventually the occurrence of static liquefaction. The relationship of macroscopic stress with microscopic and mesoscopic structures is also identified. The evolution of node degree and global efficiency versus macroscopic stress presents a two-stage development mode, and the buckling events accelerates the transition of the development mode. Our analysis elucidates the occurrence of static liquefaction from microscopic and macroscopic perspectives, which are essential for better prediction and modeling of the catastrophic failures under undrained loading path of granular materials.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49323,"journal":{"name":"Granular Matter","volume":"26 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140810741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}