scholarly journals Effect of Specimen Thickness and Compositions on the Fracture Toughness Investigations of Al7075-SiC/Al2O3 Hybrid Composites

Author(s):  
A Alhadhrami ◽  
B M Prasanna ◽  
Saleemsab Doddamani ◽  
Rajesh A M

Abstract The current work is to examine the effect of the parameters like specimen thickness, crack length to width ratio and composition of the reinforcements used in aluminium-silicon carbide/alumina particulate composite. The said composite is processed using the stir casting route. Taguchi's optimization techniques such as experiments, ANOVA and regression techniques have been utilized to investigate the parameters. Three factors and their levels considered are the composition of reinforcements (3, 6 and 9 wt%), the thickness of specimen (10, 12, 15 mm) and a/W ratio (0.45, 0.47 and 0.50). Results show increment in composition beyond 6wt%, and a/W ratio decreases the fracture toughness of hybrid composites. From Taguchi's analysis, for a/W ratio = 0.45, 12mm thick specimens and 6wt% of reinforcements in aluminium matrix exhibit the larger fracture toughness. Thus those parameters are considered to be optimized parameters. The analysis shows that the a/W ratio influences fracture toughness, followed by the composition and specimen thickness.

Author(s):  
Hareesha Guddhur ◽  
Chikkanna Naganna ◽  
Saleemsab Doddamani

The objective of this work is to investigate the process parameters which influence the fracture toughness of aluminum-silicon carbide particulate composite prepared using the stir casting technique. The Taguchi’s design of experiments is conducted to analyze the process parameters. Three parameters considered are composition of material, grain size and a/W ratio. From the Taguchi’s analysis, on compact tension specimens, aluminum 6061 reinforced with 9 wt% of the silicon carbide particles composite and a/W ratio of 0.45 are considered to be optimized parameters. Taguchi's technique result shows that the increment in the a/W ratio causes decrement in the load carrying capacity of the composite. Whereas the fine grain size of silicon carbide have better toughness values. From the ANOVA outcomes it is clear that the composition and a/W ratio of the geometry has more influence on the fracture toughness than the grain size of reinforcement.


2015 ◽  
Vol 1101 ◽  
pp. 85-88
Author(s):  
R. Suresh

Main objective of the present work is to investigate the effect of dispersiod content and the effect of chill on the mechanical properties of chilled MMC with LM25 as matrix and SiO2as dispersoid. Investigation is carried out to evaluate Ultimate Tensile Strength (UTS), Fracture toughness, Hardness, and microstructure of chilled aluminum matrix and Glass particulate composite. The glass (SiO2) particles ranging from 30-to100µm were chosen as dispersiod and added, ranging from 3to 12wt% in steps of 3%. The composite was prepared by stir-casting technique and poured into the sand molds incorporated with non-metallic and metallic chills. Test result showed that this MMC was greatly influenced by the dispersiod and chills. Fracture toughness & UTS of the composite are found to depend on the wt% of the dispersiod and chilling medium. It is observed that chill has influenced hardness of the composite. Volumetric heat capacity (VHC) of the chill is found to increase the amount of heat absorbed. Microstructure analysis has reveled uniform distribution of the dispersiod, which results in improved properties of the particulate reinforced metal matrix composite.


Aluminum metal matrix composites with various reinforcements had pronounced prospective of meeting the criteria of recent engineering applications like aerospace, automobile, breakpads, sports, this is due to their enhancement of some mechanical properties by some addition of matrix in to decide material. The present study focuses on the fabrication of 6351 aluminum MMC hybrid composites reinforced with silicon carbide and graphite powder, followed by a wear test for characterization of the material. Although several methods are available for the fabrication of Al-Sic MMC, we have employed stir casting technique due to its simplicity and economical. In this work aluminum metal matrix composites reinforced with different weight fractions of 2%, 4%, 6% and 8% graphite and silicon carbide in equal proportion characteristics were compared with Al6351 alloy. It is found that the wear properties have been improved with increase in weight fraction of the reinforcements of silicon carbide and graphite in aluminum matrix


To meet the materials demand and performance of automobile components it is necessary of developing composite materials. Aluminium Metal Matrix Composite (AMMC) are utilized to meet the industrial needs. AMMC is the mixture of aluminium and silicon carbide with minimum quantity of other materials like magnesium, aluminium oxide, graphite which are mixed in precise quantity to increase the chemical, mechanical and thermal properties of material. This paper deals with the investigation of mechanical behaviour and properties of AMMC produced by stir casting technique where silicon carbide is reinforced with alloy 6061 for using in Disc Brake. The tensile, flexural, hardness and impact tests were performed and the results showed that the hybrid composites had better properties than pure aluminium and this kind of material may be subjected to use in Disc Brake. The microstructure of the hybrid composites were analyzed using Optical Microscopy.


2006 ◽  
Vol 326-328 ◽  
pp. 935-938
Author(s):  
Yoon Suk Chang ◽  
T.R. Lee ◽  
Jae Boong Choi ◽  
Chang Sung Seok ◽  
Young Jin Kim

In this paper, the applicability of local approach is examined for SA515 Gr.60 nuclear steel through a series of finite element analyses incorporating modified GTN and Rousselier models as well as fracture toughness tests. To achieve the goal, fracture toughness test data of standard compact tension (CT) specimens are used for calibration of micro-mechanical parameters. Then, from finite element analyses employing the calibrated parameters, fracture resistance (J-R) curves of CT specimens with different crack length to width ratio, with different thickness and with/without 20% side-grooves are predicted. Finally, suitability of the numerically estimated J-R curves was verified by comparison with the corresponding experimental J-R curves.


Author(s):  
R. Suresh ◽  
Joel Hemanth

This paper deals with the assessment of dispersiod content and the effect of chill for improved mechanical properties. Investigation is carried out to evaluate Ultimate Tensile Strength (UTS), Fracture toughness, Hardness, and microstructure of chilled aluminum matrix and quartz particulate composite. In the present work, Quartz (SiO2) particles ranging from 30- to 100μm were chosen as dispersiod and added, ranging from 3 to 12 wt% in steps of 3%. The composite was prepared by stir-casting technique and poured into the sand molds incorporated with non-metallic and metallic chills. Test result showed that this MMC was greatly influenced by the dispersiod and chills. Fracture toughness & UTS of the composite are found to depend on the wt% of the dispersiod and chilling medium. It is observed that chill has influenced hardness of the composite. Volumetric heat capacity (VHC) of the chill is found to increase the amount of heat absorbed. Microstructure analysis also reveled uniform distribution of the dispersiod, which results in improved properties of the particulate metal matrix composite.


2021 ◽  
Author(s):  
Ramasubbu Narasimmalu ◽  
Ramabalan Sundaresan

Abstract The silicon carbide (SiC) reinforcement with aluminium alloy 7xxx series has been found to be limited value as per the mechanical properties and wear behaviour of previous studies. In order to improve limited mechanical properties of hybrid aluminium metal matrix composites, the SiC and OFHC Cu-Fe29Ni17Co reinforcement has been added with AA7075 alloy. Hence, the AA7075/SiC/Cu-Fe-Ni hybrid composites have been fabricated through a stir casting route under different weight percentages of SiC reinforcement. The mechanical properties such as hardness, compressive strength, tensile strength and wear rate have been investigated. The micro structure of hybrid composites found that the reinforcement particles in matrix alloy have been evenly spread. The silicon carbide and Cu-Fe-Ni alloy in aluminium solid solution has been found as well bonded interfacial reactions. The hardness, tensile strength, yield strength, compressive strength and wear rate were improved by 23.9 %, 48 %, 47 %, 15.3 % and 70 % for hybrid composite by adding 15 wt. %SiC and 15 wt. % Cu-Fe-Ni with AA7075 alloy, compared to matrix alloy.


Author(s):  
Abhilash Edacherian ◽  
Ali Algahtani ◽  
Vineet Tirth

Several challenges stand in the way of production of Metal Matrix Composites (MMCs) such as higher processing temperatures, particulate mixing, particulate-matrix interface bonding issues and ability to process into desired geometrical shapes. Although there are many literatures showing composites with single particulate reinforcements, the studies on composites with multiple reinforcing agents (hybrid composites) are found to be limited. Development of a hybrid particulate composite with optimized mechanical and tribological properties is very significant to suit modern engineering applications. In this study, Al-Si hypereutectic alloy (A390) is used as the matrix and Silicon Carbide (SiC) and Graphite (Gr) and Molybdenum di-Sulphide (MoS2) are used as particulates. Particulate volume (wt%) is varied and sample test castings are made using squeeze casting process through stir casting processing route. The evaluation of mechanical properties indicates that presence of both the hard phase (SiC) and the soft phase has distinct effect on the properties of Hybrid Composite. Composite samples were characterized to understand the performance and to meet the tribological applications. Fractography study indicated an intra-granular brittle fracture for hybrid composites. Wear study shows that Hybrid MMCs has better tribological performance compared to that of A390 alloy.


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