Temperature effects on transverse failure modes of carbon fiber/bismaleimides composites

2016 ◽  
Vol 51 (2) ◽  
pp. 261-272 ◽  
Author(s):  
Baifeng Yang ◽  
Zhufeng Yue ◽  
Xiaoliang Geng ◽  
Peiyan Wang
Keyword(s):  
Carbon Fiber ◽  
Room Temperature ◽  
Failure Modes ◽  
High Stress ◽  
Tensile Load ◽  
Plastic Behavior ◽  
Electron Microscopic ◽  
Transverse Tensile ◽  
Analytical Results ◽  
Transverse Failure

The results of experimental and numerical studies on temperature dependence of carbon fiber/bismaleimides composites subjected to transverse tensile load at −120℃, 25℃, 150℃, 170℃, 200℃ are summarized. The scanning electron microscopic fractographs showed that fibers were coated by a small amount of resin along with split resin at −120℃, melted resin attached to fibers is found in the view at 200℃ and naked fibers were observed at room temperature. It is concluded that the interfacial strength reduced with the increase of temperature. Experimental stress versus strain curves showed that modulus decreased with the increase of the temperature, and the obviously nonlinear tendency was observed at 200℃. Employed Mohr–Coulomb criterion to characterize plastic behavior of bismaleimides matrix, representative volume element based on random sequential expansion algorithm was modeled to simulate the entire damage progress with thermomechanical load. The analytical results showed that high stress concentration occurred in the matrix band between closely arranged fibers and became more severe with temperature rising. The percentage of interfacial debonding was larger at room temperature than those at higher and lower temperature. The experimental and analytical results showed that transverse failure modes at different temperature are related to thermal residual stress and the Young’s module of matrix.

Experimental Investigation on Adhesive Bonded Joints of Carbon Fiber Composite Laminates Containing Disbond Defect

2017 ◽  
Author(s):  
Ping Qiu ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Carbon Fiber ◽  
Adhesive Bonding ◽  
Phased Array ◽  
Failure Modes ◽  
Fiber Composite ◽  
Failure Process ◽  
Tensile Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Image Correlation

Adhesive bonding technology is widely used for connecting composite pipes recent years, for the adhesive joints have many advantages such as weight reduction, ease of manufacture, and more importantly, uniform stress distribution and less stress concentration within the joint region. Nevertheless, one of the limitations of adhesive joints is the difficulty in predicting the joint strength due to the presence of defects in the adhesive due to improper curing process. This paper presents an experimental study of single-lap joints with disbond defects at the adherend-adhesive interface. Different sets of adhesively-bonded singlelap joints containing varied disbond conditions were prepared and tested. The joints used carbon fiber reinforced polymer (CFRP) laminates as substrates and epoxy resin as adhesive, with ultrathin aluminum foil (10um) as disbond defects in different sizes and locations. The full deformation fields were measured using the digital image correlation (DIC) method. The samples were subjected to tensile load till failure to determine the bond strength. Before the tensile test, the defective adhesive joints were detected by a phased-array ultrasonic instrument to identify the bond-line quality of joints. The results show that the disbond defects can be detect by ultrasonic phased-array technique, and the detriment of disbond defect to the failure process can be observed and recorded by DIC system. Based on the findings, the failure modes and failure mechanism of bonded CFRP joint were further discussed.

High Strain Rate Effect on Tensile and Compressive Property of Carbon Fiber Reinforced Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 310-320
Author(s):  
Fei Weng ◽  
Yingying Fang ◽  
Mingfa Ren ◽  
Jing Sun ◽  
Lina Feng
Keyword(s):  
Carbon Fiber ◽  
Strain Rate ◽  
Tensile Testing ◽  
Failure Modes ◽  
Testing Machine ◽  
Fiber Reinforced ◽  
Static Tests ◽  
Transverse Tensile ◽  
Dynamic Loadings ◽  
Carbon Fiber Reinforced

With high strength and stiffness-to-weight ratios, Carbon-Fiber-Reinforced Polymer (CFRP) composite has been applied to the separation device of the rocket by shaped charge jet. But dynamic tensile and compressive properties of CFRP under high rate strain are still unclear. In the article, tensile testing along transverse direction are conducted. The quasi-static tests (10-3 s-1) use a universal testing machine and high dynamic loadings of 800 s-1 and 1600 s-1 tests adopt a high-speed tensile testing machine. Meanwhile, dynamic compressive tests of unidirectional and cross-ply laminated specimen under the thickness direction loading are implemented by a Split Hopkinson Pressure Bar (SHPB) from dynamic loading 500 s-1 to 2500 s-1. Test results show that compared with static tests data, both transverse tensile modulus and strength of CFRP composites materials at dynamic loadings are sensitive to tensile tests. The compressive peak stress and stiffness of specimens also have an increasing tendency with the increases of the strain rate. Furthermore, for failure mode of tensile specimens, the crack propagation of the specimen fracture is along the interface of the fiber/matrix under all loading conditions. The failure modes of compressive specimens are different as the strain rate changes. The higher the strain rate, the more severe the crushing.

Mechanical Properties of Bulk Glassy Metal after Deformation under High Temperature Conditions

2007 ◽  
Vol 340-341 ◽  
pp. 113-118
Author(s):  
Takamasa Yoshikawa ◽  
Masataka Tokuda ◽  
Tadashi Inaba
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Room Temperature ◽  
Tensile Load ◽  
Experimental Result ◽  
Uniaxial Tensile ◽  
Heating Process ◽  
Plastic Behavior ◽  
Temperature Conditions

Bulk glassy metal is an alloy with the vitreous amorphous structure. Because of various excellent properties, this material is expected to use as an alternative structural material for several engineering applications very well. Although bulk glassy metal is very little deformed plastically in the room temperature, it shows the huge super-plastic behavior over the high temperature. However, there is not many reports mentioned about the mechanical properties of bulk glassy metal after plastic deformation under high temperature condition. From the above point of view, in this study, we have investigated the lower bound of temperature at which Zr55Cu30Al10Ni5 bulk glassy metal can be plastically deformed in uniaxial tensile load. Furthermore, it is focused on the strength property of bulk glassy metal in the room temperature after deformed under various high-temperature conditions. In the experimental result, when this material was heated at temperature of 685[K] or higher, this material crystallized and the mechanical strength in room temperature drastically decreased to 200[MPa], although this material as cast had the strength over 1500[MPa]. However, this material showed sufficiently the plastic deformation at temperatures of 643[K] and the strength in room temperature after cooling was equal to as cast. It is supposed that the strength depend on its atomic structure, i.e., amorphous or crystalline, and the change of its structure is affected strongly by heating process.

scholarly journals The Effect of Stacking Sequence on Fatigue Behaviour of Hybrid Pineapple Leaf Fibre/Carbon-Fibre-Reinforced Epoxy Composites

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3936
Author(s):  
Mohd Khairul Rabani Hashim ◽  
Mohd Shukry Abdul Majid ◽  
Mohd Ridzuan Mohd Jamir ◽  
Farizul Hafiz Kasim ◽  
Mohamed Thariq Hameed Sultan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Failure Modes ◽  
High Stress ◽  
Tensile Load ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Matrix Cracking ◽  
Stacking Sequence ◽  
Fibre Breakage ◽  
Pull Out

This study examined the fatigue behaviour of pineapple leaf fibre/carbon hybrid laminate composites under various stacking sequences. The vacuum infusion technique was used to fabricate the symmetric quasi-isotropic oriented laminates, in which the stacking was varied. The laminate was tested under static and fatigue tensile load according to ASTM D3039-76 and ASTM D3479-96, respectively. Maximum tensile strength and modulus of 119.34 MPa and 6.86 GPa, respectively, were recorded for the laminate with external PALF ply and internal carbon ply oriented at [± 45°2, 0°/90°2]s (PCCP_45090). The fatigue tests showed that PCCP_45090 and CPPC_09045 (with internal PALF ply and external carbon ply oriented at [0°/90°2, ± 45°2]s) exhibited a higher useful life, especially at the high-stress level of the ultimate tensile strength. The normalised stress against the number of cycles showed that the stacking sequences of different ply orientations affected the fatigue behaviour more than the stacking sequences of the material. The laminate stacking sequence significantly affected the hysteresis energy and stiffness evolution. The scanning electron microscopy images showed that the fatigue failure modes included fibre pull-out, fibre breakage, matrix cracking, debonding, and delamination. The study concluded that PCCP_45090 exhibited an outstanding fatigue performance.

Plastic deformation of θ ' in Al-4%Cu alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 576-577
Author(s):  
Shrikant P. Bhat
Keyword(s):  
Deformation Behavior ◽  
Room Temperature ◽  
Electron Microscopic Observation ◽  
Bulk Alloy ◽  
Electron Microscopic ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Orowan Mechanism ◽  
The Subject ◽  
Cyclic Straining

deformation behavior of Al-Cu alloys aged to contain θ ' has been the subject of many investigations (e.g., Ref. 1-5). Since θ ' is strong and hard, dislocations bypass θ ' plates (Orowan mechanism) at low strains. However, at high strains the partially coherent θ ' plates are probably sheared, although the mechanism is complex, depending on the form of deformation. Particularly, the cyclic straining of the bulk alloy is known to produce gross bends and twists of θ '. However, no detailed investigation of the deformation of θ ' has yet been reported; moreover, Calabrese and Laird interpreted the deformation of θ ' as largely being elastic.During an investigation of high temperature cyclic deformation, the detailed electron-microscopic observation revealed that, under reversed straining conditions, θ ' particles are severely distorted--bent and twisted depending on the local matrix constraint. A typical electronmicrograph, showing the twist is shown in Fig. 1. In order to establish whether the deformation is elastic or plastic, a sample from a specimen cycled at room temperature was heated inside the microscope and the results are presented in a series of micrographs (Fig. 2a-e).

Effects of Mg2+ on Chromatic Structure in Isolated Chicken Liver Nuclei

1990 ◽  
Vol 48 (3) ◽  
pp. 130-131
Author(s):  
Soichiro Arai ◽  
Yuh H. Nakanishi
Keyword(s):  
Chromatin Structure ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Divalent Cations ◽  
Chromatin Condensation ◽  
Chicken Liver ◽  
Electron Microscopic ◽  
Razor Blade ◽  
Microscopic Studies ◽  
Liver Nuclei

Although many electron microscopic studies on extracted chromatin have provided considerable information on chromatin condensation induced by divalent cations, there is only a little literature available on the effects of divalent cations on chromatin structure in intact nuclei. In the present study, the effects of Mg2+ on chromatin structure in isolated chicken liver nuclei were examined over a wide concentration range of Mg2+ by scanning electron microscopy.Nuclei were prepared from chicken liver by the method of Chauveau et al. with some modifications. The nuclei were suspended in 25 mM triethanolamine chloride buffer (pH7.4) with 1 mM EDTA or in the buffer with concentrations of MgCl2 varying from 1 to 50 mM. After incubation for 1 min at 0°C, glutaraldehyde was added to 1.8% and the nuclei were fixed for 1 h at 4°C. The fixed nuclei were mixed with 15% gelatin solution warmed at about 40°C, and kept at room temperature until the mixture set. The gelatin containing the nuclei was fixed with 2% glutaraldehyde for 2-4 h, and cut into small blocks. The gelatin blocks were conductive-stained with 2% tannic acid and 2% osmium tetroxide, dehydrated in a graded series of ethanol, and freeze-cracked with a razor blade in liquid nitrogen.

scholarly journals Fatigue Resistance and Failure Behavior of Penetration and Non-Penetration Laser Welded Lap Joints

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xiangzhong Guo ◽  
Wei Liu ◽  
Xiqing Li ◽  
Haowen Shi ◽  
Zhikun Song
Keyword(s):  
Fatigue Resistance ◽  
Failure Modes ◽  
Plate Thickness ◽  
High Stress ◽  
Lap Joints ◽  
Failure Behavior ◽  
Passenger Cars ◽  
Plate Fracture ◽  
The Difference ◽  
Railway Passenger

AbstractPenetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars, while their fatigue performances and the difference between them are not completely understood. In this study, the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated. The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance, and their hardness was lower than that of the plates. The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes, whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes. The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture, respectively, and the primary cracks were initiated at welding fusion lines on the lap surface. There were long plastic ribs on the penetration plate fracture, but not on the non-penetration plate fracture. The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa, respectively, which can be used as reference stress for the fatigue design of the laser welded structures. The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.

scholarly journals Flexural bearing capacity and failure mechanism of CFRP-aluminum laminate beam with double-channel cross-section

2021 ◽  
Vol 28 (1) ◽  
pp. 139-152
Author(s):  
Teng Huang ◽  
Dongdong Zhang ◽  
Yaxin Huang ◽  
Chengfei Fan ◽  
Yuan Lin ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Cross Section ◽  
Failure Criterion ◽  
Failure Modes ◽  
Channel Cross Section ◽  
Fiber Layer ◽  
Flexural Bearing Capacity ◽  
Double Channel

Abstract In this study, the flexural bearing capacity and failure mechanism of carbon fiber-reinforced aluminum laminate (CARALL) beams with a double-channel cross-section and a 3/2 laminated configuration were experimentally and numerically studied. Two types of specimens using different carbon fiber layup configurations ([0°/90°/0°]3 and [45°/0°/−45°]3) were fabricated using the pressure molding thermal curing forming process. The double-channel CARALL beams were subjected to static three-point bending tests to determine their failure behaviors in terms of ultimate bearing capacity and failure modes. Owing to the shortcomings of the two-dimensional Hashin failure criterion, the user-defined FORTRAN subroutine VUMAT suitable for the ABAQUS/Explicit solver and an analysis algorithm were established to obtain a progressive damage prediction of the CFRP layer using the three-dimensional Hashin failure criterion. Various failure behaviors and mechanisms of the CARALL beams were numerically analyzed. The results indicated that the numerical simulation was consistent with the experimental results for the ultimate bearing capacity and final failure modes, and the failure process of the double-channel CARALL beams could be revealed. The ultimate failure modes of both types of double-channel CARALL beams were local buckling deformation at the intersection of the upper flange and web near the concentrated loading position, which was mainly caused by the delamination failure among different unidirectional plates, tension and compression failure of the matrix, and shear failure of the fiber layers. The ability of each fiber layer to resist damage decreased in the order of 90° fiber layer > 0° fiber layer > 45° fiber layer. Thus, it is suggested that 90°, 0°, and 45° fiber layers should be stacked for double-channel CARALL beams.

scholarly journals Enhanced Impact Properties of Hybrid Composites Reinforced by Carbon Fiber and Polyimide Fiber

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2599
Author(s):  
Boyao Wang ◽  
Bin He ◽  
Zhanwen Wang ◽  
Shengli Qi ◽  
Daijun Zhang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Failure Modes ◽  
Flexural Modulus ◽  
Charpy Impact ◽  
Fiber Reinforced Composites ◽  
Stacking Sequence ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Polyimide Fiber

A series of hybrid fiber-reinforced composites were prepared with polyimide fiber and carbon fiber as the reinforcement and epoxy resin as the matrix. The influence of stacking sequence on the Charpy impact and flexural properties of the composites as well as the failure modes were studied. The results showed that hybrid fiber-reinforced composites yielded nearly 50% increment in Charpy impact strength compared with the ones reinforced by carbon fiber. The flexural performance was significantly improved compared with those reinforced solely by polyimide fibers and was greatly affected by the stacking sequence. The specimens with compressive sides distributed with carbon fiber possessed higher flexural strength, while those holding a sandwich-like structure with carbon fiber filling between the outer layers displayed a higher flexural modulus.

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