Simulation-based verification of homogenization approach in predicting effective thermal conductivities of wavy orthotropic fiber composite

2019 ◽  
Vol 08 (04) ◽  
pp. 1950015
Author(s):  
C. Mahesh ◽  
K. Govindarajulu ◽  
V. Balakrishna Murthy
Keyword(s):  
Volume Fraction ◽  
Fiber Composite ◽  
Micromechanical Model ◽  
Two Stage ◽  
Micromechanics Models ◽  
Simulation Based ◽  
Homogenization Approach ◽  
Homogenized Model ◽  
Good Agreement ◽  
Thermal Conductivities

In this work, applicability of homogenization approach is verified with the micromechanics approach by considering wavy orthotropic fiber composite. Thermal conductivities of [Formula: see text]-300 orthotropic wavy fiber composite are determined for micromechanical model and compared with the results obtained by two stage homogenized model over volume fraction ranging from 0.1 to 0.6. Also, a methodology is suggested for reducing percentage deviation between homogenization and micromechanical approaches. Effect of debond on the thermal conductivities of wavy orthotrophic fiber composite is studied and compared with perfectly aligned fiber composite for different volume fraction. It is observed that results obtained by the homogenization approach are in good agreement with the results obtained through micromechanics approach. Maximum percentage deviation between homogenized and micromechanics models is 2.13%.

Effects of nano-sized silica particles on the off-axis creep performance of unidirectional fiber-reinforced polymer hybrid composites

2020 ◽  
pp. 002199832097374
Author(s):  
MJ Mahmoodi ◽  
MK Hassanzadeh-Aghdam ◽  
M Safi
Keyword(s):  
Carbon Fiber ◽  
Silica Nanoparticles ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Micromechanical Model ◽  
Silica Nanoparticle ◽  
Creep Response ◽  
Interphase Region ◽  
Nanoparticle Agglomeration ◽  
Homogenization Approach

A multi-step homogenization approach is presented to predict the off-axis creep response of hybrid polymer matrix composites (HPMCs) reinforced with unidirectional carbon fibers and silica nanoparticles. The first step deals with evaluating the viscoelastic properties of silica nanoparticle-polymer nanocomposite using the Mori-Tanaka micromechanical model. Two essential features affecting the behavior, including silica nanoparticle agglomeration and interphase region generated due to the interaction between the nanoparticle and polymer are taken into account. In the second step, the off-axis viscoelastic behavior of HPMCs is extracted from the homogenized nanocomposite and carbon fiber properties using a unit cell-based micromechanical model. Some comparative studies between the predictions and available experiment are directed to verify the homogenization process. All the model predictions are in good agreement with the experimental data. The results indicate that with increasing the fiber off-axis angle from 0° to 90°, the presence of silica nanoparticles leads to a reduction in the HPMC creep compliance. Also, the proposed multi-step homogenization approach is applied to investigate the effects of volume fraction, size and agglomeration degree of silica nanoparticles; thickness and material properties of the interphase region; and off-axis angle and volume fraction of the carbon fiber on the HPMC creep response.

A two-stage homogenization for modelling of elastic-plastic functionally graded composites

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Witold Ogierman
Keyword(s):  
Volume Fraction ◽  
Mean Field ◽  
Functionally Graded ◽  
Two Stage ◽  
Graded Materials ◽  
Content Type ◽  
Elastic Plastic ◽  
Functionally Graded Composites ◽  
Homogenization Approach ◽  
Arbitrary Volume

Purpose The purpose of this study is to develop a homogenization approach that ensures both high accuracy and time-efficient solution for elastic-plastic functionally graded composites. Design/methodology/approach The paper presents a novel two-stage hybrid homogenization approach that combines advantages of the mean field homogenization and homogenization based on the finite element method (FEM). The groundbreaking nature of the developed approach is associated with division of the hybrid homogenization procedure into two stages, which allows to very efficiently determine the solution for arbitrary volume fraction of the reinforcement. This paper concerns also on modelling of composites with randomly distributed prolate and oblate particles. For this purpose, the hybrid homogenization was implemented in the framework of the discrete orientation averaging procedure involving pseudo-grain discretization method. Findings Agreement between the results obtained using the proposed approach and the standard FEM-based homogenization is very good (up to the volume fraction of 0.3). Originality/value The proposed two-stage homogenization approach allows to obtain the solution for materials with arbitrary volume fraction of the reinforcement very efficiently; therefore, it is highly beneficial for the two-scale modeling of nonlinear functionally graded materials and structures.

Coefficients of thermal expansion of carbon nanotube-reinforced polyimide nanocomposites: A micromechanical analysis

2016 ◽  
Vol 233 (2) ◽  
pp. 169-179 ◽  
Author(s):  
R Ansari ◽  
MK Hassanzadeh-Aghdam ◽  
A Darvizeh
Keyword(s):  
Thermal Expansion ◽  
Carbon Nanotube ◽  
Present Model ◽  
Volume Fraction ◽  
Critical Role ◽  
Micromechanical Model ◽  
Temperature Deviation ◽  
Two Phases ◽  
Polyimide Matrix ◽  
Good Agreement

In this work, a unit cell-based micromechanical model with a proper representative volume element is proposed to evaluate the coefficients of thermal expansion of carbon nanotube-reinforced polyimide nanocomposites. The model takes an interphase between carbon nanotube and polyimide matrix into account which characterizes the non-bonded van der Waals interaction between two phases. The effects of some important parameters on the coefficients of thermal expansion such as thickness and adhesion exponent of interphase, temperature deviation as well as volume fraction, diameter and waviness of carbon nanotubes are investigated in detail. It is found that the interphase plays a critical role in determining the coefficients of thermal expansion and should be incorporated into the modeling of nanocomposite. According to the obtained results, there exists a specific value for carbon nanotube diameter beyond which further increasing in carbon nanotube diameter does not affect the coefficients of thermal expansion of nanocomposite. Also, the results reveal that the carbon nanotube waviness has a significant influence on the coefficients of thermal expansion of the nanocomposite. The results of the present model are compared with those of finite element method and a very good agreement is pointed out.

Effects of whisker content and dimensions on the R-curve behavior of an alumina matrix composite reinforced with silicon carbide whiskers

2001 ◽  
Vol 16 (7) ◽  
pp. 1919-1927 ◽  
Author(s):  
Takashi Akatsu ◽  
Minoru Suzuki ◽  
Yasuhiro Tanabe ◽  
Eiichi Yasuda
Keyword(s):  
Silicon Carbide ◽  
Matrix Composite ◽  
Volume Fraction ◽  
Alumina Matrix ◽  
Crack Face ◽  
Silicon Carbide Whiskers ◽  
Simulation Based ◽  
Alumina Matrix Composite ◽  
Crack Tip Opening ◽  
Good Agreement

A study was made of the effects of whisker content and dimensions on the R-curve behavior of an alumina matrix composite reinforced with silicon carbide whiskers. Experiments showed that the rising R-curve behavior is strongly enhanced by the increase in the volume fraction and the size of whiskers. Simulation based on a model of crack face whisker bridgings was made to elucidate the effects on the R-curve of the composite. The validity of the simulation was confirmed by good agreement between the experimental and the calculated R-curves. In addition to the R-curve, the distribution of crack closure stresses as well as crack tip opening displacements was also calculated, which directly reflects crack face whisker bridging processes in the composite. Then the dependence of whisker content and dimensions on the R-curve was analytically discussed taking the bridging processes into account.

Orthogonal cutting of UD-CFRP using multiscale analysis: Finite element modeling

2020 ◽  
Vol 54 (18) ◽  
pp. 2505-2518
Author(s):  
Amira Hassouna ◽  
Slah Mzali ◽  
Farhat Zemzemi ◽  
Salah Mezlini
Keyword(s):  
Finite Element ◽  
Orthogonal Cutting ◽  
Micromechanical Model ◽  
Cutting Process ◽  
Machining Process ◽  
Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Homogenization Approach ◽  
Hourglass Control ◽  
Good Agreement

Unsuitable surface quality is frequently observed in the machining of composites due to their heterogeneity and anisotropic properties. Thus, minimizing the machining damages requires a thorough understanding of the machining process. In this study, two different finite element models were developed using Abaqus/Explicit to simulate the cutting process of unidirectional carbon fiber-reinforced polymer: (i) a macromechanical model based on the homogenization approach and (ii) a micromechanical model in which the composite constituents were treated separately. The effects of CFRP mechanical properties, the energy of breaking and hourglass control were analyzed using a macromechanical model. The results revealed that CFRP properties and the numerical parameters highly influenced the cutting process. A comparative study was also performed between the macromechanical and the micromechanical models to study the mechanisms of chip formation. It was demonstrated that the material removal mechanisms for both models are in good agreement with the experimental observations for different fiber orientation angles.

scholarly journals Kinematic Prediction and Experimental Demonstration of Conditioning Process for Controlling the Profile Shape of a Chemical Mechanical Polishing Pad

2021 ◽  
Vol 11 (10) ◽  
pp. 4358
Author(s):  
Hanchul Cho ◽  
Taekyung Lee ◽  
Doyeon Kim ◽  
Hyoungjae Kim
Keyword(s):  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Shape Error ◽  
Profile Shape ◽  
Conditioning Process ◽  
Polishing Pad ◽  
Simulation Based ◽  
Diamond Conditioner ◽  
Pad Conditioning ◽  
Good Agreement

The uniformity of the wafer in a chemical mechanical polishing (CMP) process is vital to the ultra-fine and high integration of semiconductor structures. In particular, the uniformity of the polishing pad corresponding to the tool directly affects the polishing uniformity and wafer shape. In this study, the profile shape of a CMP pad was predicted through a kinematic simulation based on the trajectory density of the diamond abrasives of the diamond conditioner disc. The kinematic prediction was found to be in good agreement with the experimentally measured pad profile shape. Based on this, the shape error of the pad could be maintained within 10 μm even after performing the pad conditioning process for more than 2 h, through the overhang of the conditioner.

scholarly journals Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Ductile Iron ◽  
Volume Fraction ◽  
Energy Impact ◽  
Treatment Conditions ◽  
Mold Casting ◽  
Grade 3 ◽  
Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

scholarly journals An Intrinsic Material Tailoring Approach for Functionally Graded Axisymmetric Hollow Bodies Under Plane Elasticity

2021 ◽  
Author(s):  
Hassan Mohamed Abdelalim Abdalla ◽  
Daniele Casagrande
Keyword(s):  
Optimization Problem ◽  
Volume Fraction ◽  
Minimum Principle ◽  
Equivalent Stress ◽  
Micromechanical Model ◽  
Plane Elasticity ◽  
Functionally Graded ◽  
Pontryagin Minimum Principle ◽  
Volume Fractions ◽  
Material Tailoring

AbstractOne of the main requirements in the design of structures made of functionally graded materials is their best response when used in an actual environment. This optimum behaviour may be achieved by searching for the optimal variation of the mechanical and physical properties along which the material compositionally grades. In the works available in the literature, the solution of such an optimization problem usually is obtained by searching for the values of the so called heterogeneity factors (characterizing the expression of the property variations) such that an objective function is minimized. Results, however, do not necessarily guarantee realistic structures and may give rise to unfeasible volume fractions if mapped into a micromechanical model. This paper is motivated by the confidence that a more intrinsic optimization problem should a priori consist in the search for the constituents’ volume fractions rather than tuning parameters for prefixed classes of property variations. Obtaining a solution for such a class of problem requires tools borrowed from dynamic optimization theory. More precisely, herein the so-called Pontryagin Minimum Principle is used, which leads to unexpected results in terms of the derivative of constituents’ volume fractions, regardless of the involved micromechanical model. In particular, along this line of investigation, the optimization problem for axisymmetric bodies subject to internal pressure and for which plane elasticity holds is formulated and analytically solved. The material is assumed to be functionally graded in the radial direction and the goal is to find the gradation that minimizes the maximum equivalent stress. A numerical example on internally pressurized functionally graded cylinders is also performed. The corresponding solution is found to perform better than volume fraction profiles commonly employed in the literature.

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