Begell House Inc.
Composites: Mechanics, Computations, Applications: An International Journal
CMCA
2152-2057
4
1
2013
NEW METHODS FOR BONDING FRP STRIPS ONTO MASONRY STRUCTURES: EXPERIMENTAL RESULTS AND ANALYTICAL EVALUATIONS
1-23
10.1615/CompMechComputApplIntJ.v4.i1.10
Paolo
Foraboschi
University IUAV di Venezia, ex Convento delle Terese, Dorsoduro 2206; 30123 − Venice, Italy
Alessia
Vanin
University IUAV di Venezia, ex Convento delle Terese, Dorsoduro 2206; 30123 − Venice, Italy
perforated walls
masonry walls
FRP studs
vacuum bonding
in-plane behavior
debonding
The paper presents and analyzes the results of an experimental research on masonry walls tested first in unreinforced condition and then in FRP reinforced condition. The specimens were three real-scale perforated brick walls. The experimentation consisted in collapse testings under increasing lateral load and constant vertical load. The reinforced condition consisted in strengthening the masonry walls with Carbon Fiber-Reinforced-Polymeric strips bonded onto the masonry surface. The CFRP reinforcement was applied by using three different techniques. The first technique involved epoxy bonding of strips (common application). The second technique involved the bonding of strips with epoxy resin and strengthening the bond with studs (FRP studs embedded into the masonry and connected with the strips). The third technique consisted in the epoxy bonding of strips under vacuum (i.e., using a special vacuum-packed system to push the resin into the masonry as deep as possible). This research aimed at investigating the differences in the structural behaviors of tested perforated masonry walls due to these three different CFRP application techniques. Actually, the experimental results prove that the application technique influences both the load-carrying capacity and the ultimate horizontal displacement of the perforated tested masonry walls. The comparison between the experimental results and code provisions showed that, as regards the debonding of CFRP strips, the latter underestimate the former excessively.
DEVELOPING A METHOD FOR IDENTIFICATION OF INTEGRAL NONLINEAR MODELS OF VISCOELASTIC MEDIA BASED ON A NONLINEAR DAMPING FUNCTION
25-43
10.1615/CompMechComputApplIntJ.v4.i1.20
Yuri G.
Yanovsky
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradsky
Ave., Moscow, 125040, Russia
Yu. A.
Basistov
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradsky
Ave., Moscow, 125040, Russia
viscoelastic media
nonlinear behavior
integral models
identification
damping function
regularization
Nonlinear models of the behavior of viscoelastic media, which are based on Maxwell, Jeffries, and Voigt−Kelvin elements, are discussed. These elements are linear, while the nonlinearity function is introduced artificially by changing the stress value. Such models can be of some theoretical interest, but are useless from practical aspect, because algorithms of their identification and their nonlinearity functions are unknown. In the authors' opinion, the most promising are some integral models, in particular, a version where nonlinearity of the material function is factored to the nonlinear damping function and deformation-independent material function. Since methods of assessment of the relaxation spectrum, inherent in such model and the damping function, remain open, this gives the opportunities for further theoretical development of such approximation. The authors propose an original method for identification of such model for finite deformation conditions, which is based on analysis of relaxation spectra of viscoelastic media under the conditions of finite deformations using the method of bit-linear approximation of the nonlinear function, developed by the authors in the past. The damping function is estimated based on the experimental data, using a nonlinear regression for the minimum mean-root-square error and an algorithm for regularization of the problem. Adequacy of the proposed method of identification has been tested in full-scale experiments using a real viscoelastic medium, i.e., an elastomer uncured composite based on a natural rubber matrix, filled with hydrocarbon black.
DISPERSION OF ELASTIC MODULUS AND THE COEFFICIENT OF THERMAL EXPANSION OF 2.5D-C/SiC COMPOSITES
45-63
10.1615/CompMechComputApplIntJ.v4.i1.30
Xuming
Niu
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, CHINA
Zhigang
Sun
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, CHINA
Chunyuan
Kong
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, CHINA
Yingdong
Song
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, CHINA
2.5D-C/SiC composites
elastic modulus
coefficient of thermal expansion
pertinence
Monte Carlo method
dispersion
In this work, we investigate dispersion of the elastic moduli and the coefficient of thermal expansion (CTE) of 2.5 dimension-C/SiC ceramic matrix composites (2.5D C/SiC CMCs). A parameterized double-scale model for 2.5D-C/SiC CMCs, in which the elastic moduli and CTE predicted are found to be in good agreement with experimental results, was proposed. Then, by combining this model with a numerical simulation method, the relationship between the microparameters, elastic moduli, and the CTE could be carried out. Then, the influence of the microparameters on the elastic moduli and CTE was investigated. Finally, the dispersion of the the elastic moduli and CTE was studied by the Monte Carlo method. The analysis results show that the span of warp, the volume fraction of the fibers, and the ratio of microporosity have a significant influence on the strength properties of 2.5D-C/SiC CMCs. The elastic moduli and CTE of 2.5D-C/SiC CMCs change with a variety of microparameters. Meanwhile, a series of experiments have been performed to study the distribution of the elastic moduli and CTE of 2.5D-C/SiC CMCs. Both the experimental and theoretical distributions of the elastic moduli and CTE with a variety of microparameters fit well with the normal distribution.
AlSiC-BASED METAL MATRIX COMPOSITES FOR POWER ELECTRONIC DEVICES
65-74
10.1615/CompMechComputApplIntJ.v4.i1.40
E. N.
Kablov
Federal State Unitary Enterprise "All-Russian Research Institute of Aviation Materials", State Research Center of the Russian Federation, Moscow, Russia
D. V.
Grashchenkov
Federal State Unitary Enterprise "All-Russian Research Institute of Aviation Materials", State Research Center of the Russian Federation, Moscow, Russia
B. V.
Shchetanov
Federal State Unitary Enterprise "All-Russian Research Institute of Aviation Materials", State Research Center of the Russian Federation, Moscow, Russia
A. A.
Shavnev
Federal State Unitary Enterprise "All-Russian Research Institute of Aviation Materials", State Research Center of the Russian Federation, Moscow, Russia
A. N.
Nyafkin
Federal State Unitary Enterprise "All-Russian Research Institute of Aviation Materials", State Research Center of the Russian Federation, Moscow, Russia
S. M.
Vdovin
Ogarev Mordovia State University, Saransk, Russia
K. N.
Nishchev
Ogarev Mordovia State University, Saransk, Russia
V. V.
Chibirkin
OJSC Electrovypryamitel, Saransk, Russia
V. V.
Eliseev
OJSC Electrovypryamitel, Saransk, Russia
L. A.
Emikh
OJSC Electrovypryamitel, Saransk, Russia
metal matrix composites
porous preform
volume fraction
thermal expansion coefficient
thermal conductivity
density
specific heat capacity
bending strength
IGBT module
The influence of monomodal and bimodal powder composition on the volume fraction of the reinforcement phase in AlSiC MMC is discussed. The influence of Si on wettability of the matrix alloy during infiltration of porous preforms is substantiated. The main thermophysical and mechanical properties of AlSiC MMC are investigated.
MODELING OF VISCOUS FLUID FILTRATION IN POROUS MEDIA WITH CYLINDRICAL SYMMETRY
75-96
10.1615/CompMechComputApplIntJ.v4.i1.50
Viktoria L.
Savatorova
Central Connecticut State University, 1615 Stanley Str., New Britain,
CT 06050, USA
Alexander N.
Vlasov
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradsky Ave., Moscow, 125040, Russia
periodic porous structures with symmetry
polar coordinates
homogenization
Darcy's law of filtration
effective permeability
pressure distribution
fluid velocity
Multiscale homogenization was applied in modeling the Darcy filtration of viscous incompressible fluid in cylindrical geometry. In the 2D case, components of permeability tensors were Ñоnsidered to be periodical over both radius and angle. Averaged equations were derived for the case of a large inner radius of the cylinder. The derivation of the effective components of permeability tensor was reduced to the solution of the cell problems. Numerical simulations of pressure distribution and velocity of the fluid were performed for the case of r-periodicity of permeability tensor components.