Effects of Specimen Geometry on the Strength of Composite Materials

Kaminski, B.

doi:10.1520/stp36485s

Cited by 17 publications

(6 citation statements)

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“…Previous research, [1][2][3][4][5][6][7], has shown that the strength and stiffness of fiber reinforced composite materials depend upon the size of the composite laminates. It has been demonstrated that the degree of influence depends upon the type of scaling level used, the stacking sequence, and the mode of loading.…”

Section: Introductionmentioning

confidence: 99%

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Strength scaling in fiber composites

Kellas

Morton

1992

AIAA Journal

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A research program has been initiated to study and isolate the factors responsible for scale effects in the tensile strength of graphite/epoxy composite laminates.Four lay-ups, (±30° n/9002n)s, (±45° n/O° n/90° n)s, (90° nlO° n/90° n/O° n)s, and (±45° n/±45 ° n)s, have been chosen with appropriate stacking sequences so as to highlight individual and interacting failure modes. Four scale sizes have been selected for investigation including full scale size, 3/4, 2/4, and 1/4, with n equal to 4, 3,2, and 1, respectively. The full scale specimen size was 32 plies thick as compared to 24, 16, and 8 plies for the 3/4, 2/4, and 1/4 specimen sizes respectively.Results were obtained in the form of tensile strength, Stress/strain curves and damage development. Problems associated with strength degradation with increasing specimen size have been isolated and discussed. Inconsistencies associated with strain measurements have also been identified. Enhanced X-ray radiography was employed for damage evaluation, following step loading.It has been shown that fiber dominated lay-ups were less sensitive to scaling effects compared to the matrix dominated lay-ups. Further, it has been shown that fabrication induced damage was partly responsible for the observed behavior.Extrapolation to the full scale strength was attempted by means of three basic methods: a Weibull statistics based model, a fracture mechanics based model, and a combination model involving the previous two models in conjunction with a failure criterion. The predictive performance of each one of these models has been assessed and their applicability to the present problem has been discussed.

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Section: Introductionmentioning

confidence: 99%

“…For geometrically similar brittle materials, Eq.l may be written as: (2) where the shape parameter m is a constant for a given material. Thus, if m can be evaluated from two small size specimens, the strength of geometrically similar large size components can be predicted.…”

Section: Introductionmentioning

confidence: 99%

Strength scaling in fiber composites

Kellas

Morton

1992

AIAA Journal

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“…Generally, the strength decreased as the size of the FRP composite increased. However, this generality depended on the arrangement of fibers in the composite and the results were not always consistent [38][39][40][41]. This result was also obtained with FRP composite materials consisting of steel and GFRP panels.…”

Section: Test Results Under Accelerated Environmental Conditionsmentioning

confidence: 91%

Mechanical and Fracture Properties of Steel/GFRP Hybrid Panels for an Improved Moveable Weir after Exposure to Accelerated Natural Environmental Conditions

et al. 2019

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This study evaluated the performance of a hybrid panel in an improved moveable weir after exposure to accelerated environmental climate conditions. When exposed to a river environment, corrosion problems on improved moveable weir steel panels can occur. To address this, a hybrid panel with structure layering glass fiber-reinforced polymer (GFRP) panels on both sides of the steel panel was used. The steel was, therefore, not exposed to the outside. However, this hybrid panel is a structure that uses a mixture of two materials with different properties and there is the possibility of performance degradation when the GFRP composite material, i.e., the structure that wraps around the bond interface, and the steel panel are exposed to a river environment. Thus, we evaluated the durability of the hybrid panels by repeated exposure to long-term high temperatures, dry–wet environmental cycling, long-term freezing, and freeze–thaw cycling in an accelerated climate deterioration environment. In the flexural tests, the surface processing of the steel panel was shown to be important, with sand-blasted test specimens showing higher flexural strength. For the control specimens, the flexural strength decreased as the thickness of the GFRP panels increased. However, for the sand-blasted specimens, the flexural strength increased as the thickness of the GFRP panels increased. After exposure to accelerated climate deterioration, the flexural strength tests showed that the residual strength increased with panel thickness and that the residual strengths were greater for specimens incorporating sand-blasted steel panels. The results of our testing show that hybrid panels incorporating sand-blasted steel were adequate for use in improved moveable weirs.

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“…The reasons for such a scatter are numerous, the main one being that the material is not homogeneous, with local variations in fibre content, orientation, hollows and resin-rich zones S00697 ᭧ IMechE 1998 JOURNAL OF STRAIN ANALYSIS VOL 33 NO 3 The MS was received on 6 March 1997 and was accepted after revision for publication on 17 April 1998. [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…The fabrication processes and quality controls also have an influence [4]. In a general way, scatter is greater in these materials than in metals [5,6]. For all these reasons, in the present work a great number of static tests were performed and the cumulative distribution function (CDF) that best fitted the experimental results was used to determine the mechanical properties of GFRP studied under static load conditions.…”

Section: Introductionmentioning

confidence: 99%

Fatigue properties of a glass-fibre-reinforced polyester material used in wind turbine blades

Vázquez¹,

Bula²,

Soria

1998

The Journal of Strain Analysis for Engineering Design

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Glass-fibre-reinforced polyester (GFRP) is a composite commonly used in the manufacture of wind turbine blades. In the present work, one such material has been subject to static and dynamic tests in order to obtain data that can be applied to the design of wind turbine blades and other machine elements. The results of the static tests established a basis for the determination of a set of tension-tension (constant amplitude and sinusoidal load) dynamic tests with the aim of establishing a mathematical model in order to predict life as a function of the load state and calculate the fatigue limit. The multiplicative model (y ¼ ax b ) for y ¼ log of life and x ¼ transformed stress (a and b are characteristic parameters of the material obtained from data) matches the data quite well. The conclusion is that the GFRP studied has no fatigue limit. The possible decrease of fatigue strength of the material with solar radiation and moisture absorption was also investigated, with a negative result.

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Effects of Specimen Geometry on the Strength of Composite Materials

Cited by 17 publications

References 0 publications

Strength scaling in fiber composites

Strength scaling in fiber composites

Mechanical and Fracture Properties of Steel/GFRP Hybrid Panels for an Improved Moveable Weir after Exposure to Accelerated Natural Environmental Conditions

Fatigue properties of a glass-fibre-reinforced polyester material used in wind turbine blades

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