MODELING OF ALKALI-SILICA REACTION IN A TWO-PHASED MATERIAL MODEL

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Zarina Itam ◽  
Hazran Husain
Keyword(s):  
Material Properties ◽  
Mesoscale Model ◽  
Damage Model ◽  
Material Model ◽  
Silica Content ◽  
Alkali Silica Reaction ◽  
Complex Phenomenon ◽  
Damage Propagation ◽  
Element Technique ◽  
The Relationship

Alkali-silica reaction causes major problems in concrete structures due to the rapidity of its deformation. Factors that affect ASR include the alkali and silica content, relative humidity, temperature and porosity of the concrete, making the relationship a complex phenomenon to be understood. Hence, the finite element technique was used to build models to study the damage propagation due to ASR. Seeing that ASR initializes in the mesoscopic regions of the concrete, the damage model for ASR at the mesoscale level is studied. The heterogeneity of the mesoscale model shows how difference in material properties between aggregates and the cementitious matrix facilitates ASR expansion. With this model mesoscopic, two-phased material model, the ASR phenomenon under thermo-chemo-hygro-mechanical loading can be understood.

scholarly journals Attenuation of waves in a viscoelastic peridynamic medium

2019 ◽  
Vol 24 (11) ◽  
pp. 3597-3613 ◽  
Author(s):  
S. A. Silling
Keyword(s):  
Attenuation Coefficient ◽  
Material Properties ◽  
Cutoff Frequency ◽  
Material Model ◽  
One Dimensional ◽  
Spatial Nonlocality ◽  
Dissipative Material ◽  
The Time Domain ◽  
The Relationship ◽  
Theoretical Results

The effect of spatial nonlocality on the decay of waves in a dissipative material is investigated. The propagation and decay of waves in a one-dimensional, viscoelastic peridynamic medium is analyzed. Both the elastic and damping terms in the material model are nonlocal. Waves produced by a source with constant amplitude applied at one end of a semi-infinite bar decay exponentially with distance from the source. The model predicts a cutoff frequency that is influenced by the nonlocal parameters. A method for computing the attenuation coefficient explicitly as a function of material properties and source frequency is presented. The theoretical results are compared with direct numerical simulations in the time domain. The relationship between the attenuation coefficient and the group velocity is derived. It is shown that in the limit of long waves (or small peridynamic horizon), Stokes’ law of sound attenuation is recovered.

scholarly journals Experimental and Numerical Investigations of High-Speed Projectile Impacts on 7075-T651 Aluminum Plates

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2736 ◽  
Author(s):  
Jae-Wook Jung ◽  
Sang Eon Lee ◽  
Jung-Wuk Hong
Keyword(s):  
High Speed ◽  
High Strain ◽  
Damage Model ◽  
Computational Cost ◽  
Material Model ◽  
Constitutive Relationship ◽  
Mesh Dependency ◽  
Element Size ◽  
Aluminum Plates ◽  
The Relationship

Simulation of the material failure under high strain rate conditions is one of the most difficult problems in the finite element analyses, and many researchers have tried to understand and reproduce dynamic material fracture. In this study, we investigate a failure criterion that minimizes the mesh dependency at high strain rates and incorporates the criterion into the Johnson-Cook constitutive relationship by developing a user-defined material model. Impact tests were performed using a gas-gun system in order to investigate the response of the 7075-T651 aluminum plate in high-speed collision. On the other hand, numerical simulations are carried out by considering various element sizes and the relationship between element size and failure strain is inversely obtained using numerical results. By accommodating the relationship into the damage model and implementing in the user-defined material model, mesh dependency is significantly reduced, and sufficient accuracy is achieved with alleviated computational cost than the existing damage model. This study suggests an element size-dependent damage criterion that is applicable for impact simulation and it is expected that the criterion is useful to obtain accurate impact responses with a small computational cost.

Microscopic Damage Model for Fibrous Composites Considering Randomness in Constituent Materials

2020 ◽  
Vol 1015 ◽  
pp. 51-56
Author(s):  
Hoang Tien Dat ◽  
Ngoc Kien Nguyen ◽  
Van Truong Nguyen ◽  
Hoang Thi Hai Yen ◽  
Daichi Kurita
Keyword(s):  
Volume Fraction ◽  
Damage Model ◽  
Material Model ◽  
Short Fiber ◽  
Homogenization Method ◽  
Fibrous Composites ◽  
Damage Propagation ◽  
Plastic Composite ◽  
Heterogeneous Microstructures ◽  
Behaviour Simulation

For the multiscale damage behaviour simulation of advanced materials with hierarchical and random heterogeneous microstructures such as fibrous composites by finite element method, the mathematical homogenization method has been extended to the stochastic nonlinear multiscale method. A first-order perturbation based stochastic homogenization method was developed to calculate the microscopic strain, as well as the homogenized macroscopic properties considering randomness in the mechanical properties of constituent materials. Based on the calculated stochastic microscopic strain, the damage simulation framework was proposed for fibrous composites. For a demonstrated application, a numerical example of a single short fiber reinforced plastic composite was carried out. The damage propagation in the interphase between fiber and matrix was predicted in a stochastic way considering the physical random parameters for the interphase material model. The influences of the randomness on damage volume fraction and damage propagation of the interphase were discussed.

The Plastic Ratcheting of Thin Cylindrical Shells Subjected to Axisymmetric Thermal and Mechanical Loading

1987 ◽  
Vol 109 (4) ◽  
pp. 387-393 ◽  
Author(s):  
S. Karadeniz ◽  
A. R. S. Ponter ◽  
K. F. Carter
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Mechanical Loading ◽  
Material Properties ◽  
Thermal Loading ◽  
Cylindrical Shells ◽  
Temperature Fields ◽  
Mechanical Loads ◽  
Element Technique ◽  
The Relationship

The paper discusses the relationship between material properties and structural ratcheting for thin cylindrical shells subjected to severe thermal loading. The need to understand this problem arises in the design of Sodium Cooled Fast Reactors. A sequence of shakedown solutions are presented using a finite element technique [13]. It is shown that for tubes subject to moving temperature fields, ratcheting can occur even when no mechanical loads are applied and the material strongly cyclically hardens. Only small movements are required. Stationary thermal cycling is less likely to produce ratcheting. The calculations are compared with two sets of experimental data, which serve to confirm these conclusions.

Damage Initiation and Evolution of Panicum Miliaceum Seeds Under Compression

2017 ◽  
Author(s):  
Benjamin P. J. Hasseldine ◽  
Chao Gao ◽  
Yaning Li
Keyword(s):  
Material Properties ◽  
Material Model ◽  
Progressive Damage ◽  
Jigsaw Puzzle ◽  
Panicum Miliaceum ◽  
Damage Initiation ◽  
Nanoindentation Testing ◽  
The World ◽  
The Relationship ◽  
Damage Initiation And Evolution

Panicum Miliaceum (common millet) is an ancient crop and spread widely across the world. The high survivability and adaptability of this species is attributed to the unique structure of the seedcoat. Recently, it was found the seedcoat has a fascinating complex microstructure with star-shaped epidermis cells, articulated together via wavy suture interfaces, to form a compact jigsaw puzzle-like layer. To explore the damage initiation and evolution during quasi-static uniaxial compression, finite element simulations were performed for full seeds, and single seedcoat and kernels. A parametric study was conducted for the seedcoat and kernel to explore the relationship between material properties and damage. The material properties of the seedcoat and kernel were obtained by nanoindentation testing. A Hashin progressive damage material model was used to capture damage evolution of the seedcoat, combined with a damage plasticity model for the kernel. The simulation results show the capabilities in modeling the damage of seeds.

scholarly journals Calculators as Facilitators of Understanding Computational and Mathematical Contexts

2019 ◽  
Vol 1 (1) ◽  
pp. 177-183
Author(s):  
Jan Guncaga ◽  
Lilla Korenova ◽  
Jozef Hvorecky
Keyword(s):  
Soft Skills ◽  
Real Life ◽  
Theoretical Background ◽  
Learning Processes ◽  
Complex Phenomenon ◽  
Learning To Learn ◽  
Life Problems ◽  
The Subject ◽  
The Relationship

AbstractLearning is a complex phenomenon. Contemporary theories of education underline active participation of learners in their learning processes. One of the key arguments supporting this approach is the learner’s simultaneous and unconscious development of their ability of “learning to learn”. This ability belongs to the soft skills highly valued by employers today.For Mathematics Education, it means that teachers have to go beyond making calculations and memorizing formulas. We have to teach the subject in its social context. When the students start understanding the relationship between real-life problems and the role of numbers and formulas for their solutions, their learning becomes a part of their tacit knowledge. Below we explain the theoretical background of our approach and provide examples of such activities.

scholarly journals Development of Elastoplastic-Damage Model of AlFeSi Phase for Aluminum Alloy 6061

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 954
Author(s):  
Hailong Wang ◽  
Wenping Deng ◽  
Tao Zhang ◽  
Jianhua Yao ◽  
Sujuan Wang
Keyword(s):  
Aluminum Alloy ◽  
Constitutive Model ◽  
Material Properties ◽  
Damage Model ◽  
Scratch Test ◽  
Aluminum Alloy 6061 ◽  
Ultra Precision ◽  
Simulation Results ◽  
Alloy 6061 ◽  
Elastoplastic Damage

Material properties affect the surface finishing in ultra-precision diamond cutting (UPDC), especially for aluminum alloy 6061 (Al6061) in which the cutting-induced temperature rise generates different types of precipitates on the machined surface. The precipitates generation not only changes the material properties but also induces imperfections on the generated surface, therefore increasing surface roughness for Al6061 in UPDC. To investigate precipitate effect so as to make a more precise control for the surface quality of the diamond turned Al6061, it is necessary to confirm the compositions and material properties of the precipitates. Previous studies have indicated that the major precipitate that induces scratch marks on the diamond turned Al6061 is an AlFeSi phase with the composition of Al86.1Fe8.3Si5.6. Therefore, in this paper, to study the material properties of the AlFeSi phase and its influences on ultra-precision machining of Al6061, an elastoplastic-damage model is proposed to build an elastoplastic constitutive model and a damage failure constitutive model of Al86.1Fe8.3Si5.6. By integrating finite element (FE) simulation and JMatPro, an efficient method is proposed to confirm the physical and thermophysical properties, temperature-phase transition characteristics, as well as the stress–strain curves of Al86.1Fe8.3Si5.6. Based on the developed elastoplastic-damage parameters of Al86.1Fe8.3Si5.6, FE simulations of the scratch test for Al86.1Fe8.3Si5.6 are conducted to verify the developed elastoplastic-damage model. Al86.1Fe8.3Si5.6 is prepared and scratch test experiments are carried out to compare with the simulation results, which indicated that, the simulation results agree well with those from scratch tests and the deviation of the scratch force in X-axis direction is less than 6.5%.

Material Properties and Design Aspects of Folding Bicycle Frame

2011 ◽  
Vol 264-265 ◽  
pp. 777-782 ◽  
Author(s):  
M.A. Maleque ◽  
M.S. Hossain ◽  
S. Dyuti
Keyword(s):  
Material Properties ◽  
Raw Material ◽  
New Materials ◽  
Materials Properties ◽  
Advantages And Disadvantages ◽  
Bicycle Frame ◽  
Successful Design ◽  
Future Direction ◽  
The Relationship ◽  
Comprehensive Study

successful design of folding bicycle should take into account the function, material properties, and fabrication process. There are some other factors that should be considered in anticipating the behavior of materials for folding bicycle. In order to understand the relationship between material properties and design of a folding bicycle and also for the future direction in new materials with new design, a comprehensive study on the design under different conditions are essential. Therefore, a systematic study on the relationship between material properties and design for folding bicycle has been performed. The advantages and disadvantages matrix between conventional bicycle and folding bicycle is presented for better understanding of the materials properties and design. It was found that the materials properties of the folding bicycle frame such as fatigue and tensile strength are the important properties for the better performance of the frame. The relationship between materials properties and design is not straight forward because the behavior of the material in the finished product could be different from that of the raw material. The swing hinge technique could be a better technique in the design for the folding bicycle frame.

Evaluating Mechanical Properties of Ceramics by Relative Methods

2007 ◽  
Vol 336-338 ◽  
pp. 2406-2410
Author(s):  
Yi Wang Bao ◽  
Xiao Xue Bu ◽  
Yan Chun Zhou ◽  
Li Zhong Liu
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Ceramic Coatings ◽  
Relative Method ◽  
Tempered Glass ◽  
Theoretic Analysis ◽  
Surface Strength ◽  
Indirect Approach ◽  
Before And After ◽  
The Relationship

A relative method, defined as indirect approach to evaluate the material properties via the relationship between unknown properties and a known property, is proposed to estimate some properties that could not be measured by the traditional methods for ceramics. Experiments and theoretic analysis based on the relative method were carried out in this study to estimate the properties in following aspects: determining the temperature dependence of elastic modulus of some machineable ceramics by comparing the deflections; obtaining the modulus and strength of ceramic coatings supported by substrates, from the variation in properties of the rectangular beam samples before and after coating; estimating the residual stresses in tempered glass by comparing the change in the surface strength after strengthening.

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