Fiber Composite Strength Modeling With Extension to Life Prediction

2005 ◽  
Vol 128 (1) ◽  
pp. 41-49
Author(s):  
Edward M. Wu ◽  
John L. Kardos
Keyword(s):  
Composite Structures ◽  
Life Prediction ◽  
Failure Modes ◽  
Fiber Composite ◽  
Probability Model ◽  
Load Sharing ◽  
Local Load ◽  
Statistical Parameters ◽  
Composite Strength ◽  
Fiber Manufacturing

This paper focuses on the probability modeling of fiber composite strength, wherein the failure modes are dominated by fiber tensile failures. The probability model is the tri-modal local load-sharing model, which is the Phoenix-Harlow local load-sharing model with the filament failure model extended from one mode to three modes. This model results in increased efficiency in the determination of fiber statistical parameters and in lower cost when applied to (i) quality control in materials (fiber) manufacturing, (ii) materials (fiber) selection and comparison, (iii) accounting for the effect of size scaling in design, and (iv) qualification and certification of critical composite structures that are too large and expensive to test statistically. In addition, possible extensions to proof testing and time-dependent life prediction are discussed and preliminary data are presented.

Probability distributions for the strength of fibrous materials under local load sharing I: Two-level failure and edge effects

1982 ◽  
Vol 14 (01) ◽  
pp. 68-94 ◽  
Author(s):  
D. Gary Harlow ◽  
S. Leigh Phoenix
Keyword(s):  
Edge Effects ◽  
Upper Bound ◽  
Fiber Strength ◽  
Probability Distributions ◽  
Probability Model ◽  
Load Sharing ◽  
Local Load ◽  
Material Strength ◽  
Fibrous Materials ◽  
Fiber Element

The focus of this paper is on obtaining a conservative but tight bound on the probability distribution for the strength of a fibrous material. The model is the chain-of-bundles probability model, and local load sharing is assumed for the fiber elements in each bundle. The bound is based upon the occurrence of two or more adjacent broken fiber elements in a bundle. This event is necessary but not sufficient for failure of the material. The bound is far superior to a simple weakest link bound based upon the failure of the weakest fiber element. For large materials, the upper bound is a Weibull distribution, which is consistent with experimental observations. The upper bound is always conservative, but its tightness depends upon the variability in fiber element strength and the volume of the material. In cases where the volume of material and the variability in fiber strength are both small, the bound is believed to be virtually the same as the true distribution function for material strength. Regarding edge effects on composite strength, only when the number of fibers is very small is a correction necessary to reflect the load-sharing irregularities at the edges of the bundle.

Probability distributions for the strength of fibrous materials under local load sharing I: Two-level failure and edge effects

1982 ◽  
Vol 14 (1) ◽  
pp. 68-94 ◽  
Author(s):  
D. Gary Harlow ◽  
S. Leigh Phoenix
Keyword(s):  
Edge Effects ◽  
Upper Bound ◽  
Fiber Strength ◽  
Probability Distributions ◽  
Probability Model ◽  
Load Sharing ◽  
Local Load ◽  
Material Strength ◽  
Fibrous Materials ◽  
Fiber Element

The focus of this paper is on obtaining a conservative but tight bound on the probability distribution for the strength of a fibrous material. The model is the chain-of-bundles probability model, and local load sharing is assumed for the fiber elements in each bundle. The bound is based upon the occurrence of two or more adjacent broken fiber elements in a bundle. This event is necessary but not sufficient for failure of the material. The bound is far superior to a simple weakest link bound based upon the failure of the weakest fiber element. For large materials, the upper bound is a Weibull distribution, which is consistent with experimental observations. The upper bound is always conservative, but its tightness depends upon the variability in fiber element strength and the volume of the material. In cases where the volume of material and the variability in fiber strength are both small, the bound is believed to be virtually the same as the true distribution function for material strength. Regarding edge effects on composite strength, only when the number of fibers is very small is a correction necessary to reflect the load-sharing irregularities at the edges of the bundle.

Statistical properties of hybrid composites. I. Recursion analysis

1983 ◽  
Vol 389 (1796) ◽  
pp. 67-100 ◽  
Keyword(s):  
Hybrid Composites ◽  
Probability Model ◽  
Load Sharing ◽  
Upper Bounds ◽  
Strength Distribution ◽  
Local Load ◽  
Sharing Rule ◽  
Critical Crack ◽  
Breaking Strain ◽  
Hybrid Effect

An adaptation of the chain-of-bundles probability model for unidirectional intraply hybrid composites consisting of two types of fibres is given. Local load sharing, which is sensitive to the different elastic moduli of the fibres, is assumed for the non-failed fibre segments in each bundle. A sequence of tight upper bounds is developed for the probability distribu­tion of strength for the hybrid. The upper bounds are based upon the occurrence of k or more adjacent broken fibre segments in a bundle; this event is necessary but not sufficient for bundle failure. This development allows for a description of a critical crack size k *, dependent upon the load on the hybrid, which is a characterization of the length of a crack that catastrophically propagates causing bundle failure with virtual certainty. The upper bound developed with k *, based upon the hybrid median strength, is essentially identical to the true probability distribution of hybrid strength. It is also shown that the strength distribution for the hybrid composite has a weakest link structure in terms of a charac­teristic distribution function that is highly dependent upon the local load sharing rule, the fibre properties, and the geometrical structure of the hybrid. Numerical results from the model show that typically there is a negative ‘hybrid effect’ for hybrid breaking strain, but there is a positive ‘hybrid effect’ for hybrid tensile strength.

Modeling of fiber composite structures for the calculation of the structural intensity

2021 ◽  
Vol 262 ◽  
pp. 113631
Author(s):  
Pasquale Junior Capasso ◽  
Giuseppe Petrone ◽  
Nikolai Kleinfeller ◽  
Sergio De Rosa ◽  
Christian Adams
Keyword(s):  
Composite Structures ◽  
Fiber Composite ◽  
Structural Intensity

The effect of nanoparticle additive on surface milling in glass fiber reinforced composite structures

2021 ◽  
pp. 096739112110141
Author(s):  
Ferhat Ceritbinmez ◽  
Ahmet Yapici ◽  
Erdoğan Kanca
Keyword(s):  
Composite Materials ◽  
Glass Fiber ◽  
Composite Structures ◽  
Fiber Composite ◽  
Cutting Speed ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Glass Fiber Reinforced ◽  
Composite Layers

In this study, the effect of adding nanosize additive to glass fiber reinforced composite plates on mechanical properties and surface milling was investigated. In the light of the investigations, with the addition of MWCNTs additive in the composite production, the strength of the material has been changed and the more durable composite materials have been obtained. Slots were opened with different cutting speed and feed rate parameters to the composite layers. Surface roughness of the composite layers and slot size were examined and also abrasions of cutting tools used in cutting process were determined. It was observed that the addition of nanoparticles to the laminated glass fiber composite materials played an effective role in the strength of the material and caused cutting tool wear.

Failure Analysis of Composite Structures Using Multiscale Technique

2020 ◽  
Vol 995 ◽  
pp. 209-213
Author(s):  
Young W. Kwon
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Cell Model ◽  
Fibrous Composite ◽  
Failure Criteria ◽  
Multiscale Approach ◽  
Interface Failure ◽  
Fiber Failure ◽  
Strain Rate Effects ◽  
Constituent Material

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

scholarly journals Investigating the Effect of Interface Morphology in Adhesively Bonded Composite Wavy-Lap Joints

2021 ◽  
Vol 5 (1) ◽  
pp. 32
Author(s):  
Roya Akrami ◽  
Shahwaiz Anjum ◽  
Sakineh Fotouhi ◽  
Joel Boaretto ◽  
Felipe Vannucchi de Camargo ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Composite Structures ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Tensile Load ◽  
Lap Joints ◽  
Load Level ◽  
Displacement Curve ◽  
Interface Morphology ◽  
Angle Variation

Joints and interfaces are one of the key aspects of the design and production of composite structures. This paper investigates the effect of adhesive–adherend interface morphology on the mechanical behavior of wavy-lap joints with the aim to improve the mechanical performance. Intentional deviation from a flat joint plane was introduced in different bond angles (0°, 60°, 90° and 120°) and the joints were subjected to a quasi-static tensile load. Comparisons were made regarding the mechanical behavior of the conventional flat joint and the wavy joints. The visible failure modes that occurred within each of the joint configurations was also highlighted and explained. Load vs. displacement graphs were produced and compared, as well as the failure modes discussed both visually and qualitatively. It was observed that distinct interface morphologies result in variation in the load–displacement curve and damage types. The wavy-lap joints experience a considerably higher displacement due to the additional bending in the joint area, and the initial damage starts occurring at a higher displacement. However, the load level had its maximum value for the single-lap joints. Our findings provide insight for the development of different interface morphology angle variation to optimize the joints behavior, which is widely observed in some biological systems to improve their performance.

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