Effect of stability of the structural parameters of laminated reinforced plastics on their strength properties

1991 ◽  
Vol 26 (4) ◽  
pp. 485-491 ◽  
Author(s):  
M. R. Gurvich
Keyword(s):  
Structural Parameters ◽  
Strength Properties ◽  
Reinforced Plastics

High-temperature carbon plastics based on thermoreactive polyimide binder

2020 ◽  
pp. 89-102
Author(s):  
M. I. Valueva ◽  
I. V. Zelenina ◽  
M. A. Zharinov ◽  
M. A. Khaskov
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strength Properties ◽  
High Glass Transition Temperature ◽  
Reinforced Plastics ◽  
Carbon Plastics ◽  
Fundamental Possibility ◽  
Fiber Reinforced Plastics

The article presents results of studies of experimental carbon plastics based on thermosetting PMRpolyimide binder. Сarbon fiber reinforced plastics (CFRPs) are made from prepregs prepared by melt and mortar technologies, so the rheological properties of the polyimide binder were investigated. The heat resistance of carbon plastics was researched and its elastic-strength characteristics were determined at temperatures up to 320°С. The fundamental possibility of manufacturing carbon fiber from prepregs based on polyimide binder, obtained both by melt and mortar technologies, is shown. CFRPs made from two types of prepregs have a high glass transition temperature: 364°C (melt) and 367°C (solution), with this temperature remaining at the 97% level after boiling, and also at approximately the same (86–97%) level of conservation of elastic strength properties at temperature 300°С.

scholarly journals Physico-Mechanical Performance Evaluation of Large Pore Synthetic Meshes with Different Textile Structures for Hernia Repair Applications

2018 ◽  
Vol 26 (2(128)) ◽  
pp. 79-86 ◽  
Author(s):  
Pengbi Liu ◽  
Hong Shao ◽  
Nanliang Chen ◽  
Nanliang Cheng ◽  
Jinhua Jiang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hernia Repair ◽  
Mechanical Performance ◽  
Structural Parameters ◽  
Strength Properties ◽  
Open Loop ◽  
Burst Strength ◽  
Patch Application ◽  
Large Pore ◽  
Polypropylene Monofilament

This paper studied the relationship between the textile structure of warp knitted hernia repair meshes and their physico-mechanical properties to solve the problem of hernia patch application evaluation and clear the mechanism of hernia patch structure-performance for clinical application. Six different prototypes of large pore meshes were fabricated, including four kinds of meshes with different pore shapes: H (hexagonal), D (diamond), R (round) and P (pentagonal); and two kinds of meshes with inlays: HL (hexagonal with inlays) and DL (diamond with inlays), using the same medical grade polypropylene monofilament. All meshes were designed with the same walewise density and coursewise density. Then the influence of other structural parameters on the physico-mechanical properties of the meshes was analysed. The physico-mechanical properties of these meshes tested meet the requirements of hernia repair, except mesh DL, whose tear resistance strength (12.93 ± 2.44 N in the transverse direction) was not enough. Mesh R and P demonstrated less anisotropy, and they exhibited similar physico-mechanical properties. These four kinds of meshes without inlays demonstrated similar ball burst strength properties, but mesh HL and DL exhibited better ball burst strength than the others. All in all, uniform structures are expected to result in less anisotropy, and meshes with inlays, to some extent, possess higher mechanical properties. And the ratio of open loop number to closed loop number in a repetition of weave of fabric has marked effect on the physico-mechanical properties. Thus we can meet the demands of specific patients and particular repair sites by designing various meshes with appropriate textile structures.

Mechanical Properties of Carbon Fiber Reinforced Plastics under Hot-Wet Environment

2011 ◽  
Vol 462-463 ◽  
pp. 207-212 ◽  
Author(s):  
Hideaki Katogi ◽  
Kenichi Takemura ◽  
Yoshinobu Shimamura
Keyword(s):  
Carbon Fiber ◽  
Epoxy Resin ◽  
Strength Properties ◽  
Distilled Water ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Weight Gains ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced

Water absorption behavior and flexural strength properties of carbon fiber reinforced plastics (CFRP) under hot-wet environment were examined. Those of epoxy resin were also examined for reference. Weight gains of CFRP and epoxy resin were measured after immersion in distilled water at temperatures under 90°C. Quasi-static flexural tests of CFRP and epoxy resin were conducted after immersion for 180 days. Weight gains of CFRP and epoxy resin increased with increasing water temperature. After immersion for 180 days at 90°C, weight gain of CFRP became 3.3times higher and that of epoxy resin was 2.3 times higher than that at RT, respectively. When CFRP and epoxy resin were immersed in distilled water at 90°C, weight gains of CFRP and epoxy resin increased and then decreased. Flexural strengths of CFRP and epoxy resin decreased in distilled water at temperatures less than 90°C. Flexural strengths of dried CFRP and epoxy resin after immersion recovered but were lower than that of virgin CFRP and epoxy resin. Debonding of fiber/resin interface and crack initiation in epoxy resin in distilled water resulted in the strength reduction.

Fatigue of fibre-reinforced plastics due to cryogenic thermal cycling

2019 ◽  
Vol 53 (20) ◽  
pp. 2849-2861 ◽  
Author(s):  
Caroline Lüders ◽  
Michael Sinapius
Keyword(s):  
Thermal Cycling ◽  
Thermal Loading ◽  
Fatigue Loading ◽  
Strength Properties ◽  
Mechanical Tests ◽  
Matrix Cracking ◽  
Forming Process ◽  
Reinforced Plastics ◽  
Matrix Cracks ◽  
Induced Stresses

Due to the different thermal expansion of the constituent materials, cyclic thermal loading of fibre reinforced plastics induces alternating stresses in the material at two scales: (1) at the microscale (level of fibre–matrix-interaction) and (2) at the macroscale (level of the multidirectional laminate). Especially the effect of the thermal-induced stresses at the microscale is not comprehensively investigated yet. In the present paper, the effects of both scales are analysed. For the investigation of the microscale effect, unidirectional laminates are thermally cycled between 293 K and 90 K up to 1000 times. Afterwards, by mechanical tests at room temperature, the elasticity and strength properties in the different material directions are determined as function of the number of thermal cycles. Additionally, thermally cycled specimens are microscopically investigated in order to observe the matrix crack forming process at thermal fatigue loading. Contrary to the expectations, no significant matrix cracking and therefore no significant reduction of the elasticity and strength properties due to the thermal cycling are observed. In order to analyse the effect of the superposition of the thermal-induced stresses on micro- and macroscale, cross-ply laminates are investigated in the same manner. In these laminates matrix cracks are detected after 1000 cycles, which, however, do not reduce the stiffness and strength of the cross-ply laminates.

Effect of Notch Location on the Stress Concentration and Reliability of Notched Composite Laminates Based on a Probabilistic Approach

2007 ◽  
Author(s):  
R. Ganesan ◽  
A. K. Arumugam
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Composite Laminates ◽  
Probabilistic Approach ◽  
Stochastic Approach ◽  
Strength Properties ◽  
Practical Reasons ◽  
Commercial Aircraft ◽  
Reinforced Plastics ◽  
Reliability Based Design

Composite materials and laminates are being widely used in aerospace and automotive industries due to their less weight to stiffness ratio. Especially the use of composite laminates, made up of Carbon or Graphite Fiber Reinforced Plastics (CFRP/GFRP), in military and commercial aircraft structures has progressed steadily over the past few decades. Drilling holes and making cutouts in these laminates are unavoidable for practical reasons. These holes (or) cutouts introduces stress concentration near the hole (or) cutout edge and reduces the load-bearing capacity of the structure. Cutouts are made at the edges of composite laminates for practical purposes, which is capable of reducing the delamination effect in notched laminates. The stress distribution in notched composite laminates can vary according to the location of the notch in the laminate, which leads to the variation in strength and reliability values of notched laminates. The objective of the present work is to study the effect of notch location on the stress concentration and reliability of notched composite laminates. Composite laminate displays significant variation in material and strength properties and the stress distribution in the laminate becomes stochastic in nature. Thus the notched laminates were analyzed using a stochastic approach and designed based on a reliability-based design approach.

Effect of Irradiation on the Strength Properties of Polyethylene-Matrix Glass-Reinforced Plastics

2005 ◽  
Vol 39 (5) ◽  
pp. 295-298 ◽  
Author(s):  
S. R. Allayarov ◽  
Yu. N. Smirnov ◽  
G. P. Belov ◽  
L. D. Kispert ◽  
J. S. Trasher ◽  
...  
Keyword(s):  
Strength Properties ◽  
Matrix Glass ◽  
Polyethylene Matrix ◽  
Reinforced Plastics

scholarly journals Lightness Factors and Exertion Factors Related to its Own Mass of Fiber Reinforced Plastics (FRP) Applied in Composite Aeronautical Structures (Part 1)

2018 ◽  
Vol 47 (1) ◽  
pp. 5-22
Author(s):  
Mirosław Rodzewicz ◽  
Jerzy Lewitowicz
Keyword(s):  
Inverse Problem ◽  
Comparative Analysis ◽  
Historical Perspective ◽  
Strength Properties ◽  
Strength Analysis ◽  
Structural Elements ◽  
Composite Shells ◽  
Reinforced Plastics ◽  
Advanced Composites ◽  
Fiber Reinforced Plastics

Abstract The paper concerns an application of lightness factors in comparative analysis of strength properties of basic materials being applied in aeronautical structures – in a historical perspective. The use of lightness factors enables effective estimation how lighter will be the structural elements (of the same strength or stiffness) made from different kind of materials : traditional as well as advanced composites. It is quite easy to find the solution to the inverse problem, i.e. to estimate how differ will be stiffness or strength for the same mass of the structural elements. Very particular application of the lightness factors are noted in engineers calculations of composite gliders wing spars, where they appears as the materials constants and as structure loading factors as well. The paper presents some examples of application of the lightness factors in strength analysis of the composite shells applied in the shear webs of the wing spars, and refers to the design recommendations issued by German aviation authority (LBA).

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