Study on stress concentrations in an intraply hybrid composite sheet

2001 ◽  
Vol 22 (2) ◽  
pp. 154-159
Author(s):  
Zeng Qing-dun ◽  
Huang Xiao-qing ◽  
Lin Xue-hui
Keyword(s):  
Hybrid Composite ◽  
Composite Sheet ◽  
Stress Concentrations ◽  
Intraply Hybrid Composite

Stress Concentrations in a Hybrid Composite Sheet

1983 ◽  
Vol 50 (4a) ◽  
pp. 845-848 ◽  
Author(s):  
H. Fukuda ◽  
T. W. Chou
Keyword(s):  
Stress Concentration ◽  
Hybrid Composite ◽  
Fiber Strength ◽  
Series Representation ◽  
High Modulus ◽  
Composite Sheet ◽  
Stress Concentrations ◽  
Low Modulus ◽  
Concentration Factors ◽  
Stress Concentration Factors

This paper examines the load redistribution in a hybrid composite sheet due to fiber breakage. The hybrid composite contains both high modulus and low modulus fibers arranged in alternating positions. Stress concentration factors for both types of fibers immediately adjacent to a group of fractured fibers have been evaluated. The method of influence function and Fourier series representation are adopted. Results of stress concentration factors are presented in terms of the number of fractured fibers and their geometric arrangements. Reduction of the stress concentration factor of the high modulus fibers when dispersed among the low modulus fibers provides a theoretical explanation of the observed “hybrid effect.” The present analysis can be readily incorporated into a failure model taking into account the statistical nature of fiber strength.

Stress Concentrations in an Intermingled Hybrid Composite

1997 ◽  
Vol 64 (4) ◽  
pp. 738-742
Author(s):  
H. A. Luo ◽  
Q. Wang
Keyword(s):  
Integral Equations ◽  
Hybrid Composite ◽  
Continuous Distribution ◽  
Singular Integral Equations ◽  
High Modulus ◽  
Stress Concentrations ◽  
Shear Lag Model ◽  
Lag Model ◽  
Low Modulus ◽  
Stress Concentration Factors

This paper studies the stress redistribution in a tensile hybrid composite sheet due to the breakage of a high modulus fiber. Employing a continuous distribution of dislocations, a set of singular integral equations is established to analyze the fiber crack impinging upon weakly bonded fiber-matrix interfaces. After solving the integral equations numerically, the stress concentration factors of both high modulus and low modulus fibers are evaluated as a function of loading stress and interfacial parameters. The results are compared with those obtained from shear-lag model solution.

Mechanical performance of intraply and inter-intraply hybrid composites based on e-glass and polypropylene unidirectional fibers

2016 ◽  
Vol 51 (3) ◽  
pp. 381-394 ◽  
Author(s):  
MA Attia ◽  
MA Abd El-baky ◽  
AE Alshorbagy
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Hybrid Composite ◽  
Mechanical Performance ◽  
Hybrid Composites ◽  
Stacking Sequence ◽  
Unidirectional Fibers ◽  
Interlaminar Shear ◽  
Hybrid Configuration ◽  
Intraply Hybrid Composite

The aims of this study are to design, fabricate and investigate the mechanical properties of new hybrid composite laminates made from polypropylene-glass unidirectional fibers and epoxy matrix. Specimens were fabricated following the hand lay-up technique in intraply and inter-intraply configurations. Results are presented regarding the tensile, flexural, in-plane shear and interlaminar shear behaviors of fabricated composites with particular consideration of the effects of the plies stacking sequence and hybrid configuration. The experimental results reveal that the mechanical properties of polypropylene/epoxy composite can be effectively improved by the incorporation of glass fiber through the formation of either intraply or inter-intraply hybrid composites. With a proper choice of the hybrid configuration and the plies stacking sequence, the fabricated hybrid composites achieved property profiles close to those of homogeneous glass reinforced laminate in terms of specific properties. Resistance of the intraply hybrid composite to tensile and flexural loadings is higher than inter-intraply hybrid composites. On the other hand, the highest in-plane and interlaminar shear strengths are associated with the inter-intraply hybrid composite with glass fiber core. Additionally, an analytical analysis was also introduced to provide a good correlation with the experimental data, which give an insight on the ideal plies stacking sequence to achieve the required properties.

Sem Examinations of Glass Knives

1970 ◽  
Vol 28 ◽  
pp. 282-283
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Tensile Loading ◽  
Resultant Force ◽  
Stress Concentrations ◽  
Edge Chipping ◽  
Surface Flaws ◽  
Edge Defects ◽  
Microscopic Surface

There are two types of edge defects common to glass knives as typically prepared for microtomy purposes: 1) striations and 2) edge chipping. The former is a function of the free breaking process while edge chipping results from usage or bumping of the edge. Because glass has no well defined planes in its structure, it should be highly resistant to plastic deformation of any sort, including tensile loading. In practice, prevention of microscopic surface flaws is impossible. The surface flaws produce stress concentrations so that tensile strengths in glass are typically 10-20 kpsi and vary only slightly with composition. If glass can be kept in compression, wherein failure is literally unknown (1), it will remain intact for long periods of time. Forces acting on the tool in microtomy produce a resultant force that acts to keep the edge in compression.

Glass Knife Geometry as Seen by the SEM

1971 ◽  
Vol 29 ◽  
pp. 454-455
Author(s):  
J. Temple Black
Keyword(s):  
Low Cost ◽  
Amorphous Material ◽  
Stress Concentrations ◽  
Basic Tool ◽  
Tool Materials ◽  
Optical Inspection ◽  
Surface Flaws ◽  
Slip Planes ◽  
Glass Knife ◽  
Diamond Knife

In ultramicrotomy, the two basic tool materials are glass and diamond. Glass because of its low cost and ease of manufacture of the knife itself is still widely used despite the superiority of diamond knives in many applications. Both kinds of knives produce plastic deformation in the microtomed section due to the nature of the cutting process and microscopic chips in the edge of the knife. Because glass has no well defined slip planes in its structure (it's an amorphous material), it is very strong and essentially never fails in compression. However, surface flaws produce stress concentrations which reduce the strength of glass to 10,000 to 20,000 psi from its theoretical or flaw free values of 1 to 2 million psi. While the microchips in the edge of the glass or diamond knife are generally too small to be observed in the SEM, the second common type of defect can be identified. This is the striations (also termed the check marks or feathers) which are always present over the entire edge of a glass knife regardless of whether or not they are visable under optical inspection. These steps in the cutting edge can be observed in the SEM by proper preparation of carefully broken knives and orientation of the knife, with respect to the scanning beam.

“Cavity” formation in superplastically deformed aluminium alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 958-959
Author(s):  
A. Cziráki ◽  
E. Ková-csetényi ◽  
T. Torma ◽  
T. Turmezey
Keyword(s):  
Grain Boundaries ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Superplastic Forming ◽  
Polished Surface ◽  
Cavity Formation ◽  
Stress Concentrations ◽  
Electron Microscopic ◽  
Commercial Aluminium

It is known that the formation of cavities during superplastic deformation can be correlated with the development of stress concentrations at irregularities along grain boundaries such as particles, ledges and triple points. In commercial aluminium alloys Al-Fe-Si particles or other coarse constituents may play an important role in cavity formation.Cavity formation during superplastic deformation was studied by optical metallography and transmission scanning electron microscopic investigations on Al-Mg-Si and Al-Mg-Mn alloys. The structure of particles was characterized by selected area diffraction and X-ray micro analysis. The volume fraction of “voids” was determined on mechanically polished surface.It was found by electron microscopy that strongly deformed regions are formed during superplastic forming at grain boundaries and around coarse particles.According to electron diffraction measurements these areas consist of small micro crystallized regions. See Fig.l.Comparing the volume fraction and morphology of cavities found by optical microscopy a good correlation was established between that of micro crystalline regions.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

2013 ◽  
Vol 41 (2) ◽  
pp. 127-151
Author(s):  
Rudolf F. Bauer
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Methods ◽  
Mathematical Analysis ◽  
Internal Stresses ◽  
Stress Concentrations ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
And Performance ◽  
Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

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