scholarly journals Fatigue Modeling for Carbon Fiber/Epoxy Laminated Composites Considering Voids’ Effect

2021 ◽  
Vol 2101 (1) ◽  
pp. 012075
Author(s):  
Haolong Liu ◽  
Xuming Su ◽  
Hongtae Kang
Keyword(s):  
Experimental Data ◽  
Present Model ◽  
Laminated Composites ◽  
Experimental Tests ◽  
Stiffness Reduction ◽  
Initiation And Propagation ◽  
Stiffness Model ◽  
The Matrix ◽  
Static Tensile ◽  
Carbon Fiber Epoxy

Abstract In this article, experimental tests under static tensile loadings and tension-tension cyclic loadings were conducted for T300/924 unidirectional laminated composites at different porosity levels. On the basis of the experimental tests, a physical-based residual stiffness model for porous CFRP composites was put forward. The present model describes the deterioration of composites under cyclic loading in perspective of the initiation and propagation of cracks in the matrix, and is capable of capturing the effect of voids on fatigue behaviors of the composites. Lastly, the stiffness degradations of laminates with different void contents under various stress levels were predicted, and the predicted stiffness reduction as well as fatigue life of the material agreed well with the experimental data.

scholarly journals Mechanical Response and Damage of Woven Composite Materials Reinforced with Fique

2018 ◽  
Vol 774 ◽  
pp. 143-148 ◽  
Author(s):  
Octavio Andrés González-Estrada ◽  
Germán Díaz ◽  
Jabid E. Quiroga Mendez
Keyword(s):  
Experimental Data ◽  
Mechanical Behaviour ◽  
Structural Engineering ◽  
Mechanical Response ◽  
Experimental Tests ◽  
Woven Composites ◽  
Reinforced Composites ◽  
Woven Composite ◽  
The Matrix ◽  
Voxel Model

In this paper, we present the experimental and numerical modelling for the mechanical behaviour of woven composites reinforced with fique (furcraeaselloa) fibre, for different fique fibre woven configurations embed in an R744 epoxy matrix. The woven configurations are taken from commercial models and their mechanical properties validated by experimental data. We perform experimental tests using ASTM D3039 for the tensile response. We obtain values for Young’s modulus, ultimate strength, and deformation of unidirectional and woven reinforced composites. Scanning electron microscopy (SEM) is used for the fractographic analysis of the reinforced specimens. For the numerical model of the woven composite, we use the Texgen software to define the finite element voxel model and to estimate orthotropic mechanical parameters. Then, we determine the equivalent elastic properties of the composite, according to the materials and the fibre-matrix relations. We compare and validate the numerical results with the experimental data. We obtain stress and strain fields for the yarns and the matrix. The objective of this work is to establish a baseline of the mechanical behaviour of these natural reinforced composites to propose applications for structural engineering.

scholarly journals New Concept in Bioderived Composites: Biochar as Toughening Agent for Improving Performances and Durability of Agave-Based Epoxy Biocomposites

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 198
Author(s):  
Bernardo Zuccarello ◽  
Mattia Bartoli ◽  
Francesco Bongiorno ◽  
Carmelo Militello ◽  
Alberto Tagliaferro ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Low Cost ◽  
Experimental Tests ◽  
Short Fiber ◽  
Molding Process ◽  
Environmental Friendliness ◽  
Synthetic Materials ◽  
The Matrix ◽  
Static Tensile

Biocomposites are increasingly used in the industry for the replacement of synthetic materials, thanks to their good mechanical properties, being lightweight, and having low cost. Unfortunately, in several potential fields of structural application their static strength and fatigue life are not high enough. For this reason, several chemical treatments on the fibers have been proposed in literature, although still without fully satisfactory results. To overcome this drawback, in this study we present a procedure based on the addition of a carbonaceous filler to a green epoxy matrix reinforced by Agave sisalana fibers. Among all carbon-based materials, biochar was selected for its environmental friendliness, along with its ability to improve the mechanical properties of polymers. Different percentages of biochar, 1, 2, and 4 wt %, were finely dispersed into the resin using a mixer and a sonicator, then a compression molding process coupled with an optimized thermomechanical cure process was used to produce a short fiber biocomposite with Vf = 35%. Systematic experimental tests have shown that the presence of biochar, in the amount 2 wt %, has significant effects on the matrix and fiber interphase, and leads to an increase of up to three orders of magnitude in the fatigue life, together with an appreciable improvement in static tensile strength.

Tensile Testing of Hybrid Composite Joints

2014 ◽  
Vol 575 ◽  
pp. 452-456 ◽  
Author(s):  
Giuseppe Lamanna ◽  
Raffaele Sepe ◽  
A. Pozzi
Keyword(s):  
Tensile Testing ◽  
Failure Process ◽  
Testing Machine ◽  
Experimental Tests ◽  
Lap Joints ◽  
Stacking Sequence ◽  
Single Lap Joints ◽  
Universal Testing ◽  
Static Tensile ◽  
Carbon Fiber Epoxy

In the present paper, results of experimental tests carried out on hybrid (bonded/bolted) and adhesive composite single-lap joints are showed. The laminate adherends were made by unidirectional carbon fiber/epoxy with symmetric stacking sequence. In particular, the tests were carried out to evaluate strength and failure mode of the different joints. These joints were subjected to quasi-static tensile displacement and tests were conducted using a universal testing machine. The maximum tension load that the specimen can bear is determined and the failure process is correlated to the lay-up of the composite and joint type.

Micromechanical prediction of damage due to transverse ply cracking under fatigue loading in composite laminates

2017 ◽  
Vol 36 (5) ◽  
pp. 377-395 ◽  
Author(s):  
Bjian Mohammadi ◽  
Milad Rohanifar ◽  
Davood Salimi-Majd ◽  
Amin Farrokhabadi
Keyword(s):  
Experimental Data ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Crack Density ◽  
Strain Energy Release ◽  
Fatigue Loading ◽  
Matrix Cracking ◽  
Finite Element Software ◽  
Stiffness Reduction ◽  
The Matrix

To predict the matrix microcracking of laminated composites under fatigue loading, a novel energy based model is presented in the framework of micromechanics. For this purpose, strain energy release rate (SERR) of microcracks which had been derived previously for the whole laminate, is developed for a lamina, and then is calculated using a stress transfer-based stiffness reduction method. The advantages of the proposed method include its capability to predict the matrix cracking of general lay-ups based on the local stresses and stiffnesses of each plies separately and not being limited to a special stacking sequence. In order to predict micro-cracking propagation of composites under cyclic loading, the coefficients of the modified Paris law are extracted using the available experimental data of crack density–cycle curves. Then using multi-scale modelling and continuum damage mechanics concept, the proposed algorithm is implemented in ANSYS finite element software, as a new user defined material (Usermat). The static progress of failure on [45/−45]s laminate is simulated and the obtained results are compared with the existing experimental data in a good agreement. Finally, the results of implemented fatigue algorithm for different cross-ply laminates under different stress levels are obtained and compared with the available experimental data.

Finite Poroelasticity with Surface Effect

2014 ◽  
Vol 670-671 ◽  
pp. 646-650
Author(s):  
Chao Jun Li ◽  
Ji Li Feng
Keyword(s):  
Experimental Data ◽  
Porous Material ◽  
Present Model ◽  
Surface Effect ◽  
Pore Surface ◽  
Permeability Change ◽  
The Matrix ◽  
Adsorption Of Co ◽  
Thermodynamic Pressure ◽  
Good Agreement

This paper presents a consistent theoretical framework for describing the finite poroelasticity with surface effect. The underlying concept of additional pressure that is thought of as an equivalent thermodynamic pressure applying on the pore surface is used to detail the pore pressure. A nonlinear porosity laws is proposed for the finite deformation of porous material. With surface effect consideration, the corresponding constitutive equations are developed. The present model for both the swelling of the matrix and the permeability change of coal induced by adsorption of CO2 and CH4 are presented under different pressure conditions. It is shown that the predictions from the model are good agreement with the experimental data of sorption-induced deformation of coals.

A Useful Curve Fitting Method for Concrete Uniaxial Compressive Experiment Data

2011 ◽  
Vol 291-294 ◽  
pp. 1015-1020 ◽  
Author(s):  
Chong Jin ◽  
Hong Wang ◽  
Xiao Zhou Xia
Keyword(s):  
Experimental Data ◽  
Orthogonal Polynomial ◽  
Least Square ◽  
Base Function ◽  
Concrete Material ◽  
Fitting Method ◽  
Orthogonal Base ◽  
The Matrix ◽  
Uniform Function ◽  
Curve Fitting Method

Based on the superiority avoiding the matrix equation to be morbid for those fitting functions constructed by orthogonal base, the Legendre orthogonal polynomial is adopted to fit the experimental data of concrete uniaxial compression stress-strain curves under the frame of least-square. With the help of FORTRAN programming, 3 series of experimental data is fitted. And the fitting effect is very satisfactory when the item number of orthogonal base is not less than 5. What’s more, compared with those piecewise fitting functions, the Legendre orthogonal polynomial fitting function obtained can be introduced into the nonlinear harden-soften character of concrete constitute law more convenient because of its uniform function form and continuous derived feature. And the fitting idea by orthogonal base function will provide a widely road for studying the constitute law of concrete material.

A realistic model for transverse shear stiffness prediction of composite corrugated-core sandwich structure with bonding effect

2021 ◽  
pp. 109963622199386
Author(s):  
Tianshu Wang ◽  
Licheng Guo
Keyword(s):  
Present Model ◽  
Shear Stiffness ◽  
Realistic Model ◽  
Torsional Stiffness ◽  
Fem Model ◽  
The Core ◽  
Bonding Effect ◽  
Stiffness Model ◽  
Bonding Area ◽  
The Relationship

In this paper, a shear stiffness model for corrugated-core sandwich structures is proposed. The bonding area is discussed independently. The core is thought to be hinged on the skins with torsional stiffness. The analytical model was verified by FEM solution. Compared with the previous studies, the new model can predict the valley point of the shear stiffness at which the relationship between the shear stiffness and the angle of the core changes from negative correlation to positive correlation. The valley point increases when the core becomes stronger. For the structure with a angle of the core smaller than counterpart for the valley point, the existing analytical formulations may significantly underestimate the shear stiffness of the structure with strong skins. The results obtained by some previous models may be only 10 persent of that of the present model, which is supported by the FEM model.

scholarly journals Relative Entropy Method Applied for the Fatigue Life Distribution of Carbon Fiber/Epoxy Composites

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 224
Author(s):  
Changsheng Yuan ◽  
Yingjie Liang
Keyword(s):  
Experimental Data ◽  
Carbon Fiber ◽  
Relative Entropy ◽  
Least Squares Method ◽  
Entropy Method ◽  
Epoxy Composites ◽  
Order Moment ◽  
Kolmogorov Smirnov ◽  
Relative Entropy Method ◽  
Carbon Fiber Epoxy

This paper verifies the feasibility of the relative entropy method in selecting the most suitable statistical distribution for the experimental data, which do not follow an exponential distribution. The efficiency of the relative entropy method is tested through the fractional order moment and the logarithmic moment in terms of the experimental data of carbon fiber/epoxy composites with different stress amplitudes. For better usage of the relative entropy method, the efficient range of its application is also studied. The application results show that the relative entropy method is not very fit for choosing the proper distribution for non-exponential random data when the heavy tail trait of the experimental data is emphasized. It is not consistent with the Kolmogorov–Smirnov test but is consistent with the residual sum of squares in the least squares method whenever it is calculated by the fractional moment or the logarithmic moment. Under different stress amplitudes, the relative entropy method has different performances.

scholarly journals Homogenisation Efficiency Assessed with Microstructure Analysis and Hardness Measurements in the EN AW 2011 Aluminium Alloy

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1211
Author(s):  
Maja Vončina ◽  
Aleš Nagode ◽  
Jožef Medved ◽  
Irena Paulin ◽  
Borut Žužek ◽  
...  
Keyword(s):  
Experimental Data ◽  
Image Analysis ◽  
Phase Equilibrium ◽  
Aluminium Alloy ◽  
Phase Formation ◽  
Aluminium Alloys ◽  
Eutectic Phase ◽  
The Matrix ◽  
Equilibrium Solidification ◽  
Homogenisation Process

When extruding the casted rods from EN AW 2011 aluminium alloys, not only their homogenized structure, but also their extrudable properties were significantly influenced by the hardness of the alloy. In this study, the object of investigations was the EN AW 2011 aluminium alloy, and the effect of homogenisation time on hardness was investigated. First, homogenisation was carried out at 520 °C for different times, imitating industrial conditions. After homogenisation, the samples were analysed by hardness measurements and further characterised by microscopy and image analysis to verify the influence of homogenisation on the resulting microstructural constituents. In addition, non-equilibrium solidification was simulated using the program Thermo-Calc and phase formation during solidification was investigated. The homogenisation process enabled more rounded shape of the Al2Cu eutectic phase, equilibrium formation of the phases, and the precipitation in the matrix, leading to a significant increase in the hardness of the EN AW 2011 aluminium alloy. The experimental data revealed a suitable homogenisation time of 4–6 h at a temperature of 520 °C, enabling optimal extrusion properties.

A New Dynamic Wettability-Alteration Model for Oil-Wet Cores During Surfactant-Solution Imbibition

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 818-828 ◽  
Author(s):  
M. Hosein Kalaei ◽  
Don W. Green ◽  
G. Paul Willhite
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
History Matching ◽  
Mechanistic Model ◽  
Surfactant Solution ◽  
Experimental Tests ◽  
Quantitative Agreement ◽  
Wettability Alteration ◽  
Porous Rock ◽  
Surfactant Solutions

Summary Wettability modification of solid rocks with surfactants is an important process and has the potential to recover oil from reservoirs. When wettability is altered by use of surfactant solutions, capillary pressure, relative permeabilities, and residual oil saturations change wherever the porous rock is contacted by the surfactant. In this study, a mechanistic model is described in which wettability alteration is simulated by a new empirical correlation of the contact angle with surfactant concentration developed from experimental data. This model was tested against results from experimental tests in which oil was displaced from oil-wet cores by imbibition of surfactant solutions. Quantitative agreement between the simulation results of oil displacement and experimental data from the literature was obtained. Simulation of the imbibition of surfactant solution in laboratory-scale cores with the new model demonstrated that wettability alteration is a dynamic process, which plays a significant role in history matching and prediction of oil recovery from oil-wet porous media. In these simulations, the gravity force was the primary cause of the surfactant-solution invasion of the core that changed the rock wettability toward a less oil-wet state.

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