{"title":"A New Method to Find the Base Functions for the Method of Directly Defining the Inverse Mapping (MDDiM)","authors":"Ophir Nave","doi":"10.1142/S1756973718500087","DOIUrl":"https://doi.org/10.1142/S1756973718500087","url":null,"abstract":"In this paper, we apply a new algorithm called method of directly defining the inverse mapping (MDDiM) that was introduced by Liao for finding a semi-analytical solution to nonlinear system of differential equations. We apply this new method to the autoignition of a monodisperse fuel spray model. We use this technique for finding the base functions in the considered algorithm. Our results include a comparison between a numerical simulation and an analytical solutions derived from the MDDiM.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718500087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43190894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Elastic Contact of Rough Spheres Investigated Using a Deterministic Multi-Asperity Model","authors":"V. Yastrebov","doi":"10.1142/S1756973718410020","DOIUrl":"https://doi.org/10.1142/S1756973718410020","url":null,"abstract":"In this paper, we use a deterministic multi-asperity model to investigate the elastic contact of rough spheres. Synthetic rough surfaces with controllable spectra were used to identify individual asperities, their locations and curvatures. The deterministic analysis enables to capture both particular deformation modes of individual rough surfaces and also statistical deformation regimes, which involve averaging over a big number of roughness realizations. Two regimes of contact area growth were identified: the Hertzian regime at light loads at the scale of a single asperity, and the linear regime at higher loads involving multiple contacting asperities. The transition between the regimes occurs at the load which depends on the second and the fourth spectral moments. It is shown that at light indentation the radius of circumference delimiting the contact area is always considerably larger than Hertzian contact radius. Therefore, it suggests that there is no scale separation in contact problems at light loads. In particular, the geometrical shape cannot be considered separately from the surface roughness at least for approaching greater than one standard roughness deviation.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718410020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41296005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modeling Avascular Tumor Growth: Approach with an Adaptive Grid Numerical Technique","authors":"A. Amoddeo","doi":"10.1142/S1756973718400024","DOIUrl":"https://doi.org/10.1142/S1756973718400024","url":null,"abstract":"The mathematical modeling of complex biological systems leads to system of coupled nonlinear partial differential equations (PDEs). In this paper, we present a short review on the interaction of the urokinase plasminogen activator (uPA) system with a model for cancer cell in the avascular phase, faced using the moving mesh PDE/(MMPDE) numerical technique. The dynamical evolution of the system as a function of the diffusion properties of cancer cells has been considered, as well as the effect of hypoxia to the cancer evolution, introducing a model equation for the nutrient oxygen. The model parameters have been taken from the data existing in the literature, in particular to gauge the oxygen supply, data determined from in vivo experiments on human tumors have been used. The numerical results obtained simulating a one-dimensional portion of the biological tissue are consistent with the data existing in the literature. Our high-resolution computations show that cancer proliferation begins through highly irregular spatio-temporal pattern, which depends on cancer motility characteristics. In presence of hypoxia, the cancer proliferation patterns are still characterized by an inhomogeneous pattern, but other effects are present which depend on the model parameters, triggered by the oxygen.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718400024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47869547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Multiscale Approximation Method to Describe Diatomic Crystalline Systems: Constitutive Equations","authors":"P. Giovine","doi":"10.1142/S1756973718400012","DOIUrl":"https://doi.org/10.1142/S1756973718400012","url":null,"abstract":"We model the mechanical behavior of diatomic crystals in the light of mixture theory. Use is made of an approximation method similar to one proposed by Signorini within the theory of elasticity, by supposing that the relative motion between phases is infinitesimal. The constitutive equations for a mixture of elastic bodies in the absence of diffusion are adapted to the partially linearized case considered here, and the representation theorems for constitutive fields are applied to obtain the final expression of dynamical equations in the form which appears in theories of continua with vectorial microstructure. Comparisons are made with results of lattice theories.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718400012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45012621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Continuum-Discrete Multiscale Model for In-Plane Mechanical Modeling of Masonry Panels","authors":"L. Salvatori, P. Spinelli","doi":"10.1142/S1756973718400048","DOIUrl":"https://doi.org/10.1142/S1756973718400048","url":null,"abstract":"A multiscale numerical model for the in-plane mechanical behavior of masonry panels is presented. At the microscale, masonry is modeled by rigid blocks interacting through plane, deformable interfaces. These may represent actual mortar joints or virtual preferential fracture surfaces of the blocks (e.g., vertical surfaces crossing a block and connecting vertical joints in the brick rows above and below the considered one). Damage parameters control the interface transitions from a cohesive linear-elastic phase to an elastic-plastic one (modeling frictional sliding and contact) and, eventually, to a completely damaged one. At the panel scale, the material is treated as a finite-element discretized Cauchy continuum, homogenizing the periodic microstructure. The model allows reproducing the main anisotropic nonlinear behaviors of masonry by finite element simulations at a reasonable computational cost. With respect to more traditional phenomenological continuum nonlinear models, a more direct use of experimental data for the quantification of the model parameters is possible. Moreover, these parameters are fewer in number, since part of the complexity of the material is represented by the explicitly modeled microstructural geometry.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718400048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47631004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multiscale Damage Modeling on Aeronautical Composite Under Low Energy Impact","authors":"M. Buonsanti","doi":"10.1142/S1756973718400036","DOIUrl":"https://doi.org/10.1142/S1756973718400036","url":null,"abstract":"The purpose in this paper is to investigate about the behavior of aeronautics composite material subjected to a low energy impact. Low velocity impact in aircraft composite panels is a matter of concern in modern aircraft and can be used either from maintenance accidents tools or in-flight impact with debris. The proposed study considers the dynamics of impact between a small piece of granular material and a large body of composite material. The principal aim is to simulate the impact of runway debris throw-up by the landing gear against an airplane structure. In this simulation, I want to investigate on CFRP composite panels affected by granular particles at low speed in theoretical and experimental tests. The finite element analysis, initially on the macroscale and subsequently on the microscale, shows the damage inside the composite according to the experimental results, but by itself, this classic numerical approach is little suitable to investigate the complete phenomenon. Developing the question, in first step by the classical approach, appears difficult on macro and microscale relationship besides their reciprocal influence over the deformation field. To resolve the last question, I will perform the first step on macroscale FEM analysis and then reduce from the size and effects over an opportune created RVE, such that microscale main effects as local delamination can be reproduced.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973718400036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41684564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis of Fatigue Crack Growth Rate Data in an Aircraft 7175-T7351 Al-Alloy Generated at Different Accredited Laboratories with Probability Life Assessment Example","authors":"I. Černý","doi":"10.1142/S175697371850004X","DOIUrl":"https://doi.org/10.1142/S175697371850004X","url":null,"abstract":"Estimation of safety and reliability of engineering structures and components containing cracks or crack-like defects is one of the most important application field of fracture mechanics particularly in components, where limited defects can be accepted. Such design philosophy is usually called “damage tolerance”, formerly “safe life”. In such cases, safety and reliability of further operation, residual life assessment and specification of interval of damage development inspections are important issues. Existing exact knowledge on fatigue crack growth (FCG) parameters is an essential condition. Results of FCG measurement in an Al 7175-T7351 alloy of a particularly high homogeneity, carried out as a part of the Proficiency Test Program organized by Exova in France are presented in this work. Results were evaluated in terms of parameters C and m of the Paris dependence in the stable growth region. To pass the test program successfully, a particular attention was paid to improve and verify direct current potential drop (DCPD) method being used for the crack length measurement. In the paper, the results of the FCG measurements generated by different participating laboratories were analyzed. A distinct correlation between C and m values, so called “coupling”, was found and demonstrated. Some paradoxes of the assessment of laboratories were addressed, namely the fact that a laboratory assessed as unacceptable concerning one of the parameters generated much more accurate and useful data than another laboratory with a better assessment. Eventually, the results including their scatter were used to provide an example of probabilistic assessment of a simple beam residual life to show practical actual impacts of the scatter on the life assessment.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S175697371850004X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47075358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theory of a Time Domain Boundary Element Development for the Dynamic Analysis of Coupled Multiphase Porous Media","authors":"P. Maghoul, B. Gatmiri","doi":"10.1142/S175697371750007X","DOIUrl":"https://doi.org/10.1142/S175697371750007X","url":null,"abstract":"This paper presents an advanced formulation of the time-domain two-dimensional (2D) boundary element method (BEM) for an elastic, homogeneous unsaturated soil subjected to dynamic loadings. Unlike the usual time-domain BEM, the present formulation applies a convolution quadrature which requires only the Laplace-domain instead of the time-domain fundamental solutions. The coupled equations governing the dynamic behavior of unsaturated soils ignoring contributions of the inertia effects of the fluids (water and air) are derived based on the poromechanics theory within the framework of a suction-based mathematical model. In this formulation, the solid skeleton displacements ui, water pressure pw and air pressure pa are presumed to be independent variables. The fundamental solutions in Laplace transformed-domain for such a dynamic u−pw−pa theory have been obtained previously by authors. Then, the BE formulation in time is derived after regularization by partial integrations and time and spatial discretization...","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2017-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S175697371750007X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41643322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boundary Element Crystal Plasticity Method","authors":"I. Benedetti, V. Gulizzi, V. Mallardo","doi":"10.1142/S1756973717400030","DOIUrl":"https://doi.org/10.1142/S1756973717400030","url":null,"abstract":"A three-dimensional (3D) boundary element method for small strains crystal plasticity is described. The method, developed for polycrystalline aggregates, makes use of a set of boundary integral equations for modeling the individual grains, which are represented as anisotropic elasto-plastic domains. Crystal plasticity is modeled using an initial strains boundary integral approach. The integration of strongly singular volume integrals in the anisotropic elasto-plastic grain-boundary equations are discussed. Voronoi-tessellation micro-morphologies are discretized using nonstructured boundary and volume meshes. A grain-boundary incremental/iterative algorithm, with rate-dependent flow and hardening rules, is developed and discussed. The method has been assessed through several numerical simulations, which confirm robustness and accuracy.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2017-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S1756973717400030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45146870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}