Improvement of Fatigue Strength and Impact Properties of Plain-Woven CFRP Modified with Micro Fibrillated Cellulose

2008 ◽  
Vol 47-50 ◽  
pp. 133-136 ◽  
Author(s):  
Norifumi Takagaki ◽  
Kazuya Okubo ◽  
Toru Fujii
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Carbon Fiber ◽  
Impact Load ◽  
Static Fatigue ◽  
Test Results ◽  
Static Properties ◽  
Impact Properties ◽  
Matrix Cracks ◽  
The Matrix

This study investigated the effect of the enhancement by addition of Micro Fibrillated Cellulose (MFC) on the static, fatigue and impact properties of plain-woven CFRP. Test results showed that the addition of MFC little contributed to the improvement of static properties. However, the initiation of matrix cracks between woven carbon fiber cloths was prevented under cyclic loading so that the fatigue life of the CFRP was improved by the modification with MFC. The ductility of plain-woven CFRP was also acquired under impact load by the addition of the MFC to the matrix.

Mechanical Properties of Matrix Hybrid Thick-Composites

Materials ◽  
2004 ◽  
Author(s):  
Hiroyuki Hamada ◽  
Asami Nakai ◽  
Kazuya Eto ◽  
Kenichi Sugimoto
Keyword(s):  
Mechanical Properties ◽  
Hybrid Composite ◽  
High Performance ◽  
Impact Load ◽  
Unsaturated Polyester ◽  
In Situ Observation ◽  
Impact Properties ◽  
The Matrix ◽  
Low Modulus ◽  
Thick Composites

For the purpose of more safety boats, the large thickness of outer plates is required to increase flexural stiffness, strength and impact properties. Some problems in mechanical properties are generated by increasing in thickness because the effect of interlaminar shearing of Thick-composites on whole mechanical properties is greater than that of thin-composites. We have investigated the matrix hybrid composite with two kinds of unsaturated polyester, one was hard type resin with low toughness and the other was flexible type resin with low modulus and high toughness. In this study, matrix hybrid composite was focused and applied to Thick-composites. First, the flexural properties were investigated and the micro fracture progress was precisely observed with in-situ observation using replica method. Then, impact properties of the Thick-composites were examined and the availability of matrix hybrid composite was investigated. It was concluded that the matrix hybrid composite achieved high performance in both static and impact load.

Matrix and interface microcracking in carbon fiber/polymer structural micro-battery

2019 ◽  
Vol 53 (25) ◽  
pp. 3615-3628 ◽  
Author(s):  
Johanna Xu ◽  
Janis Varna
Keyword(s):  
Carbon Fiber ◽  
Energy Release ◽  
Crack Growth ◽  
Matrix Crack ◽  
Matrix Interface ◽  
Release Rates ◽  
Matrix Cracks ◽  
The Matrix ◽  
Energy Release Rates ◽  
Coating Matrix

In this paper, the propagation of radial matrix cracks and debond cracks at the coating/matrix interface in unidirectional carbon fiber structural micro-battery composite are studied numerically. The micro battery consists of a solid electrolyte-coated carbon fiber embedded in an electrochemically active polymer matrix. Stress analysis shows that high hoop stress in the matrix during charging may initiate radial matrix cracks at the coating/matrix interface. Several 2-D finite element models of the transverse plane with different arrangements of fibers and other matrix cracks were used to analyze the radial matrix crack growth from the coating/matrix interface of the central fiber in a composite with a square packing of fibers. Energy release rates of radial cracks along two potential propagation paths are calculated under pure electrochemical loading. The presence of a radial matrix crack imposes changes in the stress distribution along the coating/matrix interface, making debonding relevant for consideration. Results for energy release rates show that the debond crack growth is governed by mode II.

scholarly journals Temperature dependence of statistical fatigue strengths for unidirectional carbon fiber reinforced plastics under tension loading

2019 ◽  
Vol 54 (14) ◽  
pp. 1797-1806 ◽  
Author(s):  
Masayuki Nakada ◽  
Yasushi Miyano
Keyword(s):  
Fatigue Strength ◽  
Carbon Fiber ◽  
Longitudinal Direction ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
The Matrix ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced ◽  
Tension Loading

The formulation for time- and temperature-dependent statistical static and fatigue strengths for carbon fiber reinforced plastics laminates is newly proposed based on the physically serious role of resin viscoelasticity as the matrix of carbon fiber reinforced plastics. In this study, this formulation is applied to the tensile strength along the longitudinal direction of unidirectional carbon fiber reinforced plastics constituting the most important data for the reliable design of carbon fiber reinforced plastics structures which are exposed to elevated temperatures for a significant period of their operative life. The statistical distribution of the static and fatigue strengths under tension loading along the longitudinal direction of unidirectional carbon fiber reinforced plastics were measured at various temperatures by using resin-impregnated carbon fiber reinforced plastics strands as specimens. The master curves for the fatigue strength as well as the static strength of carbon fiber reinforced plastics strand were constructed based on the time–temperature superposition principle for the matrix resin viscoelasticity. The long-term fatigue strength of carbon fiber reinforced plastics strand can be predicted by using the master curve of fatigue strength.

The Effects of Specimen Size on the Very High Cycle Fatigue Properties of FV520B-I

2015 ◽  
Author(s):  
Ming Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Specimen Size ◽  
Fatigue Properties ◽  
Test Results ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Heat Effects ◽  
Very High

The authors researched the effects of specimen size on the very high cycle fatigue properties of FV520B-I through ultrasonic fatigue testing. The test results showed that the very high cycle fatigue mechanism was not changed and the fatigue properties declined as the specimen size increased. The S-N curve moved downward and the fatigue life decreased under the same stress level maybe due to the heat effects of large specimens in tests. The fatigue strength and the fatigue life were predicted by relevant models. The prediction of fatigue strength was close to test result, and the prediction of fatigue life was less effective compared with the previous prediction of small size specimen test results.

Fatigue Behavior of a Nanocomposite under a Fighter Aircraft Spectrum Load Sequence

2013 ◽  
Vol 24 ◽  
pp. 58-66 ◽  
Author(s):  
C.M. Manjunatha ◽  
Ramesh Bojja ◽  
N. Jagannathan
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Epoxy Matrix ◽  
Fatigue Behavior ◽  
Crack Density ◽  
Load Spectrum ◽  
Fighter Aircraft ◽  
Matrix Cracks ◽  
The Matrix ◽  
Load Sequence

Two different E-glass fiber reinforced plastic (GFRP) composite laminates having quasi isotropic [(+45/-45/0/90)2]S layup sequence were fabricated viz., GFRP with neat epoxy matrix (GFRP-neat) and GFRP with modified epoxy matrix (GFRP-nano) containing 9 wt. % of CTBN rubber micro-particles and 10 wt.% of silica nanoparticles. Standard fatigue test specimens were machined from the laminates and end-tabbed. Spectrum fatigue tests under a standard fighter aircraft load spectrum, mini-FALSTAFF, were conducted on both the composites at various reference stress levels and the experimental fatigue life expressed as number of blocks to fail, were determined. The stiffness of the specimen was determined from the load-displacement data acquired at regular intervals during the fatigue test. The matrix cracks development in the test specimens with fatigue cycling was determined through optical photographic images. The fatigue life of GFRP-nanocomposite under mini-FALSTAFF load sequence was observed to be enhanced by about four times when compared to that of GFRP-neat composite due to presence of micro-and nanoparticles in the matrix. The stiffness degradation rate and matrix crack density was considerably lower in GFRP-nanocomposite when compared to that of GFRP-neat composite. The underlying mechanisms for improved fatigue performance of GFRP-nanocomposite are discussed.

Static and Dynamic Mechanical Performance of Carbon Fiber Reinforced Polyethersulfone Composites

2019 ◽  
Vol 895 ◽  
pp. 265-271 ◽  
Author(s):  
B. Harshavardhan ◽  
R. Ravishankar ◽  
Bheemappa Suresha ◽  
S. Srinivas
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Mechanical Performance ◽  
Mechanical Test ◽  
Dynamic Environment ◽  
Flexural Properties ◽  
Static Properties ◽  
Dynamic Mechanical ◽  
The Matrix ◽  
Static Mechanical

This study has been carried out to demonstrate the effect of short carbon fiber (SCF) loading on static and dynamic mechanical performance of polyethersulfone (PES) composites. Different combinations of SCF/PES composites were prepared by extrusion followed by injection molding. The static mechanical properties such as hardness, tensile and flexural properties of PES based composites were analyzed following ISO standards. As engineering materials, the polymer composites with high modulus as well as excellent damping properties are of great interest in aerospace and automotive industries for severe dynamic environment. Furthermore, in addition to static properties of composites, dynamic mechanical behaviour of PES based composites was evaluated. Mechanical test results showed that increasing the SCF wt. % in the composites increases the hardness, tensile and flexural properties. Furthermore, the optimal SCF loading was found to be 30 wt. % for significantly improving the overall composite mechanical performance. Upon the reinforcing of SCFs, an improvement in the storage modulus was found. Based on the fractographic analysis, orientation and aligned structure of carbon fibers, good bonding of fibers within the matrix and better fiber-matrix interaction were the primary reasons leading to the improvement of mechanical properties. The optimized composite (PES with 30 wt. % of SCF) could be used in automotive components like frames, flap covers and gears of printing machinery.

The Presentation of Fatigue Data for Fatigue Life Calculations

1956 ◽  
Vol 60 (545) ◽  
pp. 331-346 ◽  
Author(s):  
C. L. Bore
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Strength ◽  
Mean Stress ◽  
Test Results ◽  
Concentration Effects ◽  
Fatigue Data ◽  
Strength Alloy ◽  
Static Failure ◽  
Notched Components

SummaryA simple and convenient “ endurance chart” for the presentation of basic fatigue data is described, where static failure is regarded as simply fatigue failure in one cycle of loading.This chart shows the effects of mean stress, residual stress and pre-tension, and displays several interesting features of fatigue data. It is easily constructed directly from fatigue test results, and is very well suited to the calculation of stress concentration effects, including “ plastic relief ” effects.With the aid of such charts the relative fatigue strengths and structural efficiencies of different materials may be readily compared, and it is clearly shown that in certain circumstances a “ high-strength” alloy may in fact have considerably less fatigue strength than a “ medium-strength ” alloy at a given life, or conversely a lower life at a given stress level.It is demonstrated that the fatigue life of a component subjected to combined mean stress and alternating stress may be found only with a knowledge of the complete fatigue characteristics of the material (such as are presented in the endurance chart); and that attempts to estimate fatigue life from spot-value comparisons, such as the fatigue strength at an arbitrary given endurance, can be dangerously inaccurate. A chart of the form described thus forms a valuable step towards the accurate calculation of fatigue life.The method is illustrated by the provision of endurance charts for 14S-T (L.65), 75S-T, and D.T.D.683; and with experimental results for notched components of L.65 and D.T.D.683.An example illustrates the application of the chart to the calculation of the fatigue life for the case of two independent systems of loading acting on a pressure cabin with circular window cut-outs.

scholarly journals Influence of the Hole Surface Integrity on the Fatigue Strength of an Aluminium Drilled Part

2021 ◽  
pp. 34-40
Author(s):  
Alexandra Lacombe ◽  
Yann Landon ◽  
Manuel Paredes ◽  
Clément Chirol ◽  
Audrey Benaben
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Surface Integrity ◽  
Positive Influence ◽  
Test Results ◽  
Orbital Drilling ◽  
Significant Difference ◽  
Open Hole

AbstractFatigue strengths of aluminium 2024-T351 open-hole specimens drilled by axial and orbital drilling processes are compared. Two drilling diameters (Ø) are studied: 6.35 mm and 9.53 mm. Surface integrity characterization tests are conducted in order to study the link between drilling processes, surface integrity and fatigue life. Fatigue test results show an increase of the fatigue life for specimens drilled by axial drilling for Ø = 9.53 mm and no significant difference in fatigue life between the two drilling processes for Ø = 6.35 mm. Surface integrity results show no impact of the roughness on the fatigue strength but a potential positive influence of the hole microhardness on the fatigue life.

Finite Element Modeling of Local Damage in Kevlar/Carbon Fiber Sandwich Under Low Velocity Impact

2007 ◽  
Author(s):  
Saiphon Jacque ◽  
Robert Rizza ◽  
Mohammad Mahinfalah
Keyword(s):  
Carbon Fiber ◽  
Impact Load ◽  
Composite Plates ◽  
Low Velocity Impact ◽  
Face Sheet ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Fiber Layer ◽  
Impact Properties ◽  
The Impact

Impact properties of carbon fiber and Kevlar or hybrid (3K carbon fiber/1500 Denier Kevlar) combination sandwich composite plates were numerically investigated in this study. The goal of this research was to define the change in impact properties as results of replacing the carbon fiber layer on the impact-side face sheet with combinations of carbon fiber/Kevlar or carbon fiber/hybrid. Information on impact energy and maximum impact force obtained from previous experiments were applied to validate the model input properties. The models were then used to characterize the mechanism of the reduction in the global stiffness of the sandwich plate due to the sequence of the damage in the foam core and the face sheet corresponding to the variation of the laminate mixture and loading energy. Results from this study could be of assistance to determining structure integrity with respect to the composite combination under impact load.

Experimental Study on Fatigue Strength of Small-Diameter Socket-Welded Pipe Joints

1998 ◽  
Vol 120 (2) ◽  
pp. 149-156 ◽  
Author(s):  
M. Higuchi ◽  
A. Nakagawa ◽  
K. Iida ◽  
M. Hayashi ◽  
T. Yamauchi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Welded Joints ◽  
Fatigue Tests ◽  
Defect Size ◽  
Test Results ◽  
Pipe Surface ◽  
Bending Fatigue ◽  
Nominal Diameter

The authors conducted fully reversed four-point bending fatigue tests on socket-welded joints 20 to 50 mm in nominal diameter, and rotating bending fatigue tests on socket-welded joints 20 mm in nominal diameter. S-N curves for 33 series of different types of specimens were obtained. Examination was made of the effects of various parameters listed in the forthcoming on fatigue strength such as steel types (carbon and stainless steels), diameter, pipe thickness (Sch), fillet shape, slip-on gap, and root defects. Bending fatigue test results indicated fatigue strength for socket-welded joints to be less for longer life regions than reported in the literature by Markl and George (1950). Fatigue strength for socket joints of 50 mm nominal diameter at 107 cycles of fatigue life was 46 MPa for carbon steel and 60 MPa for stainless steel with nominal bending stress on the pipe surface. Cracks generally originated from the toe when stress amplitude was high with shorter fatigue life and from the root when amplitude was small with longer life. Fatigue strength was greater for smaller diameter, larger Sch (thicker pipe wall), final welding pass on the toe of pipe side, and in the absence of a slip-on gap. From fatigue test results of socket joints with weld defects at the roots, an empirical equation for the relation of defect size with decrease in fatigue strength was established. Fatigue strength was found to decrease to 60 percent the original level for defect size 25 percent of leg length.

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