scholarly journals An Estimation Approach for the Effective Elastic Modulus of Lightweight Bulk Filling Material with Compressible Inclusions and Imperfect Interfaces

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3563 ◽  
Author(s):  
Chengxuan Li ◽  
Jianguo Wang ◽  
Fakai Dou
Keyword(s):  
Elastic Modulus ◽  
Volume Fraction ◽  
Effective Elastic Modulus ◽  
Confining Pressure ◽  
Imperfect Interface ◽  
Expanded Polystyrene ◽  
Filling Material ◽  
Curing Time ◽  
Elastic Interface ◽  
Reinforced Clay

In this study, an approach is developed to estimate the density and effective elastic modulus of a lightweight bulk filling material made up of expanded polystyrene (EPS) and cement-reinforced clay (matrix). First, a representative volume element (RVE) is composed of cell A (an EPS and matrix) and cell B (matrix only). Then, an elastic interface is introduced to describe the discontinuity of displacement at the interface between EPS beads and matrix. Third, an Eshelby compliance tensor is modified in cell A to include the effects of imperfect interface and the compressibility of EPS beads. Finally, the approach for the density and effective elastic modulus of the EPS beads mixed cement-reinforced clay is verified with experimental data. The compressibility ratio of lightweight clay is compared under different confining pressures and curing times. It is found that the imperfect interface has salient impacts on the effective elastic modulus with the increase of volume fraction of inclusions. The interface parameters (α and β) vary with curing time and confining pressure. At the same curing time, the parameter α is almost constant regardless of confining pressure but the parameter β changes with confining pressure. The compressibility ratio is smaller for longer curing time if the confining pressure is constant.

scholarly journals Physical and Mechanical Properties of a Bulk Lightweight Concrete with Expanded Polystyrene (EPS) Beads and Soft Marine Clay

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1662 ◽  
Author(s):  
Jianguo Wang ◽  
Bowen Hu ◽  
Jia Hwei Soon
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Content ◽  
Mass Density ◽  
Physical And Mechanical Properties ◽  
Confining Pressure ◽  
Expanded Polystyrene ◽  
Triaxial Tests ◽  
Filling Material ◽  
Confining Pressures

The variation of physical and mechanical properties of the lightweight bulk filling material with cement and expanded polystyrene (EPS) beads contents under different confining pressures is important to construction and geotechnical applications. In this study, a lightweight bulk filling material was firstly fabricated with Singapore marine clay, ordinary Portland cement and EPS. Then, the influences of EPS beads content, cement content, curing time and confining pressure on the mass density, stress–strain behavior and compressive strength of this lightweight bulk filling material were investigated by unconsolidated and undrained (UU) triaxial tests. In these tests, the mass ratios of EPS beads to dry clay (E/S) were 0%, 0.5%, 1%, 2%, and 4% and the mass ratios of cement to dry clay (C/S) were 10% and 15%. Thirdly, a series of UU triaxial tests were performed at a confining pressure of 0 kPa, 50 kPa, 100 kPa, and 150 kPa after three curing days, seven curing days, and 28 curing days. The results show that the mass density of this lightweight bulk filling material was mainly controlled by the E/S ratio. Its mass density decreased by 55.6% for the C/S ratio 10% and 54.9% for the C/S ratio 15% when the E/S ratio increased from 0% to 4% after three curing days. Shear failure more easily occurred in the specimens with higher cement content and lower confining pressure. The relationships between compressive strength and mass density or failure strain could be quantified by the power function. Increasing cement content and reducing EPS beads content will increase mass density and compressive strength of this lightweight bulk filling material. The compressive strength with curing time can be expressed by a logarithmic function with fitting correlation coefficient ranging from 0.83 to 0.97 for five confining pressures. These empirical formulae will be useful for the estimation of physical and mechanical properties of lightweight concretes in engineering application.

Bounds for Elastic Moduli of Multiphase Short-Fiber Composites

1984 ◽  
Vol 51 (3) ◽  
pp. 540-545 ◽  
Author(s):  
S. Nomura ◽  
T.-W. Chou
Keyword(s):  
Elastic Modulus ◽  
Aspect Ratio ◽  
Correlation Functions ◽  
Volume Fraction ◽  
Perturbation Expansion ◽  
Effective Elastic Modulus ◽  
Fiber Composites ◽  
Short Fiber ◽  
Spherical Particles ◽  
Upper And Lower Bounds

This paper examines upper and lower bounds of the effective elastic modulus of unidirectional short-fiber composites. The short-fibers are modeled by aligned ellipsoidal inclusions of the same aspect ratio but not necessarily the same size. We adopt a perturbation expansion of the composite local strain field by using the Green function tensor. Explicit expressions of the effective elastic modulus are derived up to the third-order term by use of the information on the correlation functions. The variational method is then employed to optimize the bounds of the effective modulus in a closed form. Numerical examples of the bounds as functions of the fiber aspect ratio and the fiber volume fraction are given for a glass/epoxy system. The present approach predicts narrower bounds than those of Hashin and coworkers for the limiting cases of spherical particles and continuous fibers since their bounds corresponds to a model that take the correlation functions up to the second order into account.

Numerical Simulation for Mechanical Behavior of Carbon Black Filled Rubber Composites Based on Plane Stress Model

2012 ◽  
Vol 476-478 ◽  
pp. 2543-2547
Author(s):  
Qing Li ◽  
Xiao Xiang Yang
Keyword(s):  
Elastic Modulus ◽  
Carbon Black ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Effective Elastic Modulus ◽  
Volume Element ◽  
Stress Model ◽  
Rubber Composites ◽  
Particle Volume ◽  
Filled Rubber

In this paper, Representative Volume Element with random distribution pattern has been built and applied to study and analyze the macro mechanical properties of the carbon black filled rubber composites by the micromechanical finite element method. And numerical simulations under uniaxial compression have been made by two-dimensional plane stress model. The periodic boundary conditions are imposed on each Representative Volume Element in order to ensure the compatibility of the deformation field. The dependence of the macroscopic stress-strain behavior and the effective elastic modulus of the composites, on particle distribution pattern, particle volume fraction and particle stiffness has been investigated and discussed. It is shown that the stiffness of the composite is increased considerably with the introduction of carbon black filler particles, and the effective elastic modulus of the composite is increased with the increase of the particle volume fraction.

Novel cellular perlite–epoxy foams: Effect of density on mechanical properties

2016 ◽  
Vol 53 (4) ◽  
pp. 425-442 ◽  
Author(s):  
Haleh Allameh-Haery ◽  
Erich Kisi ◽  
Thomas Fiedler
Keyword(s):  
Elastic Modulus ◽  
Failure Modes ◽  
Shear Failure ◽  
Volume Fraction ◽  
Volcanic Glass ◽  
Effective Elastic Modulus ◽  
High Volume ◽  
Density Range ◽  
Longitudinal Splitting ◽  
Closed Cell

A novel type of economical lightweight foam with density from 0.15 to 0.45 g/cm3 was made from a high volume fraction of expanded volcanic glass (perlite) in an epoxy matrix. The compressive strength, effective elastic modulus, and modulus of toughness of the foams all increased with the foam density. The strength increased linearly, peaking at 1.7 MPa whereas the effective elastic modulus and modulus of toughness increased at parabolically increasing and decreasing rates, respectively. The specific compressive stress of the newly developed foam in the density range of 0.3–0.44 g/cm3 is comparable with foams made from alumina, aluminium–silicon carbide, closed cell phenolic resin, and closed cell polypropylene. Post-test SEM observations coupled with photogrammetry during the tests revealed three different failure modes: longitudinal splitting, shear failure, and compression failure were present over the whole density range. The material was found to be a good candidate for the stiffening cores within sandwich panels.

Effect of Fiber Waviness and Cluster on Effective Elastic Properties of Fiber-Reinforced Composites

2015 ◽  
Author(s):  
Bincheng Huang ◽  
Lingyu Sun ◽  
Ligang Wang ◽  
Tongguang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Volume Fraction ◽  
Effective Elastic Modulus ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Fiber Waviness ◽  
Bridging Model ◽  
Element Method

Carbon fiber-reinforced polymers (CFRPs) are widely applied in lightweight automotive design due to their high specific stiffness and strength. However, it is difficult to achieve an ideal performance due to defects from manufacturing process. For example, fiber waviness and cluster are two typical manufacture defects in the process of Liquid Composite Molding (LCM). The effective elastic modulus of CFRPs with fiber waviness is studied by finite element method, and the stress-transfer mechanisms between the fibers and matrix is explained theoretically, the modified bridging model, which correlates the stress state in fibers with that in matrix. Additionally, the influence of fiber cluster on the effective elastic modulus of CFRPs is also investigated by finite element method. When the volume fraction of fibers in matrix is higher than 20%, the fiber waviness will decrease the longitudinal modulus E11 greatly, but also increase the transverse modulus E22 slightly. For CFRPs with cured fibers, the proposed modified bridging model has higher prediction accuracy than the rule of mixture. When the cluster degree is less than 1%, the effective elastic modulus of CFRPs with fibers distributed randomly will not be influenced obviously. For straight fibers, the reinforcement effect on elastic modulus E11 and shear modulus G12 decreases slightly with increasing cluster degree.

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

scholarly journals Measurements of sea-ice flexural stiffness by pressure characteristics of flexural-gravity waves

2013 ◽  
Vol 54 (64) ◽  
pp. 51-60 ◽  
Author(s):  
Aleksey Marchenko ◽  
Eugene Morozov ◽  
Sergey Muzylev
Keyword(s):  
Elastic Modulus ◽  
Gravity Waves ◽  
Water Depth ◽  
Water Pressure ◽  
Field Measurements ◽  
Effective Elastic Modulus ◽  
Flexural Stiffness ◽  
Flexural Gravity Waves ◽  
Using Data ◽  
Relative Errors

Abstract A method to estimate the flexural stiffness and effective elastic modulus of floating ice is described and analysed. The method is based on the analysis of water pressure records at two or three locations below the bottom of floating ice when flexural-gravity waves propagate through the ice. The relative errors in the calculations of the ice flexural stiffness and the water depth are analysed. The method is tested using data from field measurements in Tempelfjorden, Svalbard, where flexural-gravity waves were excited by an icefall at the front of the outflow glacier Tunabreen in February 2011.

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