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Fractography

About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.


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TL;DR: In this paper, the fractographic features observed in aerospace composites failed under tensile loads were analyzed and correlated with the loading conditions, and the change in fracture mode in the final fracture was attributed to superimposition of bending loads.
Abstract: This paper describes fractographic features observed in aerospace composites failed under tensile loads. Unidirectional Carbon Fibre Reinforced Plastic (UD CFRP) and Unidirectional Glass Fibre Reinforced Plastic (UD GFRP) composite specimens were fabricated and tested in tension. The morphology of fractured surfaces was studied at various locations to identify failure mechanism and characteristic fractographic features. CFRP composites displayed transverse crack propagation and the fracture surface showed three distinct regions, viz., crack origin, propagation and final failure. Significant variations in the fractographic features were noticed in crack propagation and final failure regions. Crack propagation region exhibited brittle fracture with chevron lines emanating from the crack origin. The entire crack propagation region exhibited radial marks on the individual fibre broken ends. On the other hand, the final fracture region revealed longitudinal matrix splitting and radial marks in majority of locations, and chop marks at some locations. The change in fracture mode in the final fracture was attributed to superimposition of bending loads. GFRP composites exhibited broom like fracture with extensive longitudinal splitting with radial marks present on individual fibre broken ends. Transverse fracture was observed at a few locations. These fracture features were analyzed and correlated with the loading conditions.

37 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of various sintering parameters on the densification, electrochemical properties in 1-M H2SO4 solution, coefficient of friction (CoF) and dry sliding wear resistance was investigated.

37 citations

Journal ArticleDOI
TL;DR: In this article, fatigue crack propagation behavior of four materials from the fluorocarbon family, including PTFE without filler (virgin pTFE), PTFEs with 15% glass fiber, PTFe with 15 % graphite particles, and PDFE with 25 % glass fiber were studied.
Abstract: Polytetrafluoroethylenes (PTFEs) and their composites are a special class of fluorocarbons with very high chemical resistance and wide service temperature. This makes them good candidate materials for load-bearing components exposed to harsh environments, including some space applications. In the present work, fatigue crack propagation (FCP) behavior of four materials from the fluorocarbon family, including PTFE without filler (virgin PTFE), PTFE with 15% glass fiber, PTFE with 15% graphite particles, and PTFE with 25% glass fiber, were studied. Tension/tension FCP experiments were carried out using single-edge notch (SEN) specimens under load control. The maximum stress was kept constant at 8 MPa for each material at a frequency of 3 Hz. The minimum to maximum stress ratio was 0.27. FCP data such as the number of cycles, crack length, and hysteresis loops were recorded in order to establish the crack speed, the energy release rate, J*, and the change in work Wɛi. Parameters that characterize the resistance of PTFEs to FCP have been successfully determined by the modified crack layer (MCL) model. These parameters are γ′, the specific energy of damage, which reflects the FCP resistance of the PTFE materials, and the dissipative characteristic of the materials, β′. It has been found that the MCL model describes the behavior of the PTFEs over the entire range of the energy release rate and discriminates the subtle effects introduced by changing the filler type and dosage as well as the processing conditions. The values of the specific energy of damage γ′ have been found to decrease by increasing the dosage of the fiberglass fillers. Graphite particulate filler also reduced the value of γ′ more than fiberglass filler for the same dosage. Microscopic analysis of the fracture surface in the stable crack propagation region of each material revealed that there exists a strong correlation between the value of γ′ and the amount of damage energy manifested by different mechanisms and species during the fatigue process.

37 citations

Journal ArticleDOI
TL;DR: In this paper, the microstructure, tensile deformation and final fracture behavior of porous Ti were investigated using PMMA as a space holder, and the failure mechanism has been discussed by taking the intrinsic microstructural features into consideration.
Abstract: Porous Ti with the porosity of 50% and the average pore size of 200 μm was prepared by powder metallurgy technique using polymethyl methacrylate (PMMA) as space holder. The microstructure, tensile deformation and final fracture behavior were investigated. Porous Ti reveals two kinds of pores: open interpenetrated macro-pores in the range of 30–260 μm and micro-pores with the average size of 9 ± 2 μm. The stepped surface of macro-pores consists of polygons with angles of 30°, 60° or 90°. The ultimate tensile strength of porous Ti is 81 MPa. Porous Ti fails with the formation of shear bands at 45° to the tensile axis. The cracking of the struts on porous Ti is controlled primarily by the macro-pores. Fractography shows evidence of the brittle cleavage fracture in porous Ti. The failure mechanism has been discussed by taking the intrinsic microstructural features into consideration.

37 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023120
2022254
2021229
2020206
2019205
2018176