Cumulative Damage Mechanism of Short Fiber type C/SiC under Compression

A cumulative damage mechanism for short fiber type C/SiC during shear loading–unloading testing was examined and quantified using Iosipescu specimens parallel in the in-plane and through-thickness plane, and by using modified fracture and damage mechanics theory referring to measured damage characteristics (crack length, number and angle). A nonlinear stress–strain relation was found for both specimens. Decrease in the apparent modulus was confirmed with increased peak stress, although permanent strain increased. Inelastic strain of the decomposed tensile direction derived from shear stress was greater than that of the compressive one. Cracks propagated perpendicularly to the tensile direction, intruding on the boundary of the transverse fibers and connecting to other cracks. The theoretical damage mechanics model succeeded to predict the stress–strain relation, proposing that the shear mechanical properties are predictable by measuring the damage characteristics.

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Evaluation Method for Seismic Fatigue Damage of Plant Pipeline

Journal of Pressure Vessel Technology ◽

10.1115/1.4042220 ◽

2019 ◽

Vol 141 (2) ◽

Author(s):

Fumio Inada ◽

Michiya Sakai ◽

Ryo Morita ◽

Ichiro Tamura ◽

Shin-ichi Matsuura ◽

...

Keyword(s):

Fatigue Damage ◽

Nuclear Power ◽

Power Plants ◽

Evaluation Method ◽

Response Spectrum ◽

Damage Mechanism ◽

Peak Frequency ◽

Cumulative Damage ◽

Cumulative Absolute Velocity ◽

Seismic Index

Although acceleration and cumulative absolute velocity (CAV) are used as seismic indexes, their relationship with the damage mechanism is not yet understood. In this paper, a simplified evaluation method for seismic fatigue damage, which can be used as a seismic index for screening, is derived from the stress amplitude obtained from CAV for one cycle in accordance with the velocity criterion in ASME Operation and Maintenance of Nuclear Power Plants 2012, and the linear cumulative damage due to fatigue can be obtained from the linear cumulative damage rule. To verify the performance of the method, the vibration response of a cantilever pipe is calculated for four earthquake waves, and the cumulative fatigue damage is evaluated using the rain flow method. The result is in good agreement with the value obtained by the method based on the relative response. When the response spectrum obtained by the evaluation method is considered, the value obtained by the evaluation method has a peak at the peak frequency of the ground motion, and the value decreases with increasing natural frequency above the peak frequency. A higher peak frequency of the base leads to a higher value obtained by the evaluation method.

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Analysis of Additive Alignment in a 90∘ Elbow Channel

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132520500327 ◽

2020 ◽

Vol 28 (04) ◽

pp. 2050032

Author(s):

Hoang Minh Khoa Nguyen ◽

Dong-Wook Oh

Keyword(s):

Flow Visualization ◽

Fiber Type ◽

Weight Ratio ◽

High Strength ◽

Short Fiber ◽

Industrial Applications ◽

Injection Molding Process ◽

Molding Process ◽

Corner Region ◽

Liquid Polymer

Short-fiber reinforced polymer composites have been widely used in industrial applications due to high strength-to-weight ratio, versatile manufacturing process, and etc. The alignment of fiber type additives plays an important role in the mechanical properties of a composite material. In this paper, an injection molding process was imitated with a liquid polymer composite flow inside a [Formula: see text] elbow channel. We performed a flow visualization experiment and analyzed the additive alignment of carbon fiber flowing in the polydimethylsiloxane (PDMS) medium. By analyzing the flow visualization images, the angle changes at the corner region of the elbow channel were calculated. At the corner region, the change of passage direction leads to the change of fiber orientation. It was observed that near to the convex region, fibers have angle change values larger than the fibers traveling near to the concave region.

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Experimental and Numerical Research on Open-Hole Strength and Damage Mechanism of Regularly Arrayed Short Fiber Reinforced Polymer Composite

Polymers ◽

10.3390/polym12071622 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1622

Author(s):

Junfeng Hu ◽

Xutong Zhang ◽

Zhou Chen ◽

Wenkang Guo ◽

Hang Li ◽

...

Keyword(s):

Tensile Strength ◽

Damage Mechanism ◽

Short Fiber ◽

Numerical Control ◽

Fiber Reinforced Polymer ◽

Fiber Reinforced ◽

Reinforced Polymer ◽

Fiber Reinforced Polymer Composites ◽

Open Hole ◽

Continuous Carbon Fiber

Laminates with unidirectionally arrayed chopped strands (UACS) are one of the advanced short fiber reinforced polymer composites (SFRP) with significant application prospect, which greatly improves mechanical properties compared to the traditional SFRP, meanwhile ensuring excellent flowability. In practice, composite laminate with an open hole is one of the typical connective components, and it is necessary to clarify the allowable load and damage tolerance performance of notched structures. In the present study, UACS laminates were fabricated using the continuous carbon fiber reinforced polymer (CFRP) prepreg, on which regularly arrayed bi-angled slits were introduced by a commercial numerical control cutter. The tensile strength and strain distribution around the open hole of the notched UACS laminate were experimentally investigated, while the damage progression near the open hole of the notched UACS laminate was analyzed by the finite element method (FEM). The tensile strength of the notched UACS laminate was measured at 298 MPa, which is about 60% of the strength of the unnotched UACS laminate. The simulation results match well with the experimental results, although there is a little overestimate on strength, by about 5% and 7%, for unnotched and notched UACS laminates, respectively. The final critical failure mode for the notched UACS laminate is mainly dominated by the delamination instead of the fiber breakage in the unnotched UACS laminate.

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Short-Fiber-Reinforced Elastomer Composites

Rubber Chemistry and Technology ◽

10.5254/1.3535189 ◽

1977 ◽

Vol 50 (5) ◽

pp. 945-958 ◽

Cited By ~ 106

Author(s):

J. E. O'Connor

Keyword(s):

Fiber Type ◽

Cellulose Fibers ◽

Short Fiber ◽

Bonding Agents ◽

Fiber Dispersion ◽

Adhesion Promoters ◽

Fiber Aspect Ratio ◽

Matrix Adhesion ◽

Glass Carbon ◽

Fiber Matrix

Abstract The reinforcement of elastomers with short fibers results in composites with a wide variety of properties. The performance and properties are a function of fiber type, fiber content, fiber aspect ratio, fiber orientation, fiber dispersion, fiber-matrix adhesion, processing methods, and properties of the elastomer matrix. A composite with almost any desired property can be obtained by manipulation of these parameters. Of the five fibers studied in this work, glass and carbon are the poorest for increasing mechanical properties. The cellulose, aramid, and nylon fibers all reinforce elastomers to give composites of approximately the same magnitude in properties. Alignment of reinforcing fibers by milling creates a significant anisotropy in the composite properties. The degree of fiber alignment is best for glass, carbon, and cellulose fibers. The uniformity of fiber dispersion is again best for glass, carbon, and cellulose fibers. Aramid and nylon fibers tend to clump together and do not disperse easily. Fiber-to-matrix adhesion is a problem. No evidence of consistently good fiber-matrix adhesion is observed except for the precoated cellulose fibers. The interaction between fiber and elastomer can only improve with a coating or sizing that is compatible with both the fiber and its matrix. Adhesion-promoting bonding agents also improve fiber-matrix adhesion. However, each fiber and/or elastomer may be influenced differently by a bonding agent. Adhesion promoters specific to the type of composite being prepared must be sought in order to obtain optimum properties.

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Evaluation Method for Seismic Fatigue Damage of Plant Pipeline

Volume 8: Seismic Engineering ◽

10.1115/pvp2017-65596 ◽

2017 ◽

Author(s):

Fumio Inada ◽

Michiya Sakai ◽

Ryo Morita ◽

Ichiro Tamura ◽

Shin-ichi Matsuura ◽

...

Keyword(s):

Fatigue Damage ◽

Nuclear Power ◽

Power Plants ◽

Evaluation Method ◽

Response Spectrum ◽

Damage Mechanism ◽

Peak Frequency ◽

Cumulative Damage ◽

Cumulative Absolute Velocity ◽

Seismic Index

Although acceleration and cumulative absolute velocity (CAV) are used as seismic indexes, their relationship with the damage mechanism is not yet understood. In this paper, a simplified evaluation method for seismic fatigue damage, which can be used as a seismic index for screening, is derived from the stress amplitude obtained from CAV for one cycle in accordance with the velocity criterion in ASME Operation and Maintenance of Nuclear Power Plants 2012, and the linear cumulative damage due to fatigue can be obtained from the linear cumulative damage rule. To verify the performance of the method, the vibration response of a cantilever pipe is calculated for four earthquake waves, and the cumulative fatigue damage is evaluated using the rain flow method. The result is in good agreement with the value obtained by the method based on the relative response. When the response spectrum obtained by the evaluation method is considered, the value obtained by the evaluation method has a peak at the peak frequency of the ground motion, and the value decreases with increasing natural frequency above the peak frequency. A higher peak frequency of the base leads to a higher value obtained by the evaluation method.

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Muscle damage induced by eccentric contractions of 25% strain

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.6.2498 ◽

1991 ◽

Vol 70 (6) ◽

pp. 2498-2507 ◽

Cited By ~ 182

Author(s):

R. L. Lieber ◽

T. M. Woodburn ◽

J. Friden

Keyword(s):

Time Course ◽

Fiber Type ◽

Tibialis Anterior Muscle ◽

Eccentric Contraction ◽

Damage Mechanism ◽

Treatment Method ◽

Oxidative Capacity ◽

Morphological Properties ◽

Fast Twitch ◽

Passive Stretch

Contractile and morphological properties were measured in the rabbit tibialis anterior muscle 1 h after isometric contraction (IC), passive stretch (PS), or eccentric contraction (EC). Maximal tetanic tension (Po) was reduced after 30 min of PS (P less than 0.001), IC (P less than 0.001), or EC (P less than 0.0001). However, the magnitude of the force deficit was a function of the treatment method. After 30 min of cyclic PS, Po decreased by 13%, whereas after IC or EC, Po decreased by 31 and 69%, respectively. The time course of tension decline in the various groups suggested that the EC-induced injury occurred during the first few minutes of treatment. Although the morphology of samples from the PS and IC groups appeared normal, eccentrically exercised muscles exhibited portions of abnormally large fibers (diam greater than or equal to 110 microns) when viewed in cross section. Examination of 231 such fibers from 6 muscles revealed that all enlarged fibers were exclusively of the fast-twitch glycolytic fiber type. Although no ultrastructural abnormalities were observed in any of the muscles from the IC or PS groups, a significant portion of the fibers in the EC group displayed various degrees of disorganization of the sarcomeric band pattern. Taken together, these studies highlight the importance of fiber oxidative capacity in EC-induced injury, which may be related to the damage mechanism.

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Influence of sinusoidal strain and fiber type to stress and surface temperature of short fiber-rubber composite under dynamic fatigue.

Sen i Gakkaishi ◽

10.2115/fiber.44.12_606 ◽

1988 ◽

Vol 44 (12) ◽

pp. 606-612 ◽

Cited By ~ 2

Author(s):

Satoshi Mashimo ◽

Masayoshi Nakajima ◽

Yoshio Yamaguchi ◽

Michio Ashida

Keyword(s):

Surface Temperature ◽

Fiber Type ◽

Short Fiber ◽

Rubber Composite ◽

Dynamic Fatigue

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Thermal Shock Behavior of Fiber-Reinforced Ceramic Composites

MRS Proceedings ◽

10.1557/proc-365-441 ◽

1994 ◽

Vol 365 ◽

Author(s):

Raj N. Singh ◽

Hongyu Wang

Keyword(s):

Thermal Shock ◽

Thermal Stresses ◽

Fiber Type ◽

Damage Mechanism ◽

Ceramic Composites ◽

Fiber Reinforced ◽

Quench Temperature ◽

Monolithic Ceramics ◽

Thermal Shock Behavior ◽

Original Strength

ABSTRACTThe influence of fiber type and method of composite fabrication on the thermal shock behavior of 2-D fiber-reinforced ceramic composites is studied. Thermal shock tests are performed using a water quench technique, and thermal shock damage is characterized by both destructive and nondestructive techniques. It is shown that the composites possessed superior resistance to thermal shock damage than the monolithic ceramics. Catastrophic failure due to severe thermal stresses is prevented in composites and a significant portion of their original strength is retained at a quench temperature difference up to 1000°C. These results along with an analysis of the thermal shock damage mechanism based on the destructive and nondestructive tests is described.

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