Using the theory of critical distances to predict notch effects in fibre composites

Morgan, David; Quinlan, Simon; Taylor, David

doi:10.1016/j.tafmec.2022.103285

Cited by 9 publications

(9 citation statements)

References 21 publications

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“…The size of the finite elements was selected in such a way that at least 5 finite elements were located within the critical distance. [55] These were sufficient to give accurate stress-distance information in the critical regions. According to the point method (PM):…”

Section: Tcdmentioning

confidence: 99%

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The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

et al. 2023

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The purpose of this work is to analyze the stress-raisers that affect the tensile strength and fatigue resistance of GFRP parts using the point and line methods of the theory of critical distances (TCD) to obtain a quantitative measure of the defect size that can be tolerated by the composite before it fails. In the course of the work, a method combining TCD and the Weibull function was developed. In the course of the work, GFRP structural fiberglass for electrical purposes was tested under uniaxial quasi-static and cyclic loading with digital image correlation (DIC) and acoustic emission (AE), as well as a numerical simulation of deformation. The studied specimens were plain (without a stress-raiser) and notched (V-shaped) with different notch root radii and depths. The results were used to determine the material critical distances. In this case, two approaches to TCD were used: line (LM) and point (PM) methods. To analyze the experimental results, finite element modeling was applied using the ANSYS software package. As a result, the linearized maximum principal stresses were obtained on the central line passing through the top of the stress raiser. Thus, the values of the critical distances of the material were determined by PM and LM. Based on the data obtained, the sizes of permissible defects in the studied fiberglass were established that do not affect the tensile and fatigue strength of the material. The paper illustrates the cumulative energy, peak amplitudes, and distributions of the frequency of the spectral maximum of acoustic emission signals obtained after the destruction of specimens by fatigue test. Evolutions of deformation fields on the specimen surface were recorded using a Vic-3D contactless optical video system and the DIC.

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Section: Tcdmentioning

confidence: 99%

“…By doing so, a refined mesh of about 0.025 mm element size in the critical region of the notch tip was applied. The size of the finite elements was selected in such a way that at least 5 finite elements were located within the critical distance [55]. These were sufficient to give accurate stress-distance information in the critical regions.…”

Section: Tcdmentioning

confidence: 99%

The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

et al. 2023

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“…These composite laminate structures usually include discontinuities such as cut-outs for access and fastener holes for joining and inevitably become vulnerable regions under thermo-mechanical loading [1][2][3]. Understanding their notched behaviors is necessary for designing these complex structures, in which various parts are mostly connected with bolts and rivets [4]. The effect of these discontinuities on the mechanical performances is an important issue because it causes a relatively large reduction in strength compared to the unnotched laminates.…”

Section: Introductionmentioning

confidence: 99%

Notched Behaviors of Carbon Fiber-Reinforced Epoxy Matrix Composite Laminates: Predictions and Experiments

2023

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This paper experimentally studied the influence of the notch shape and size on the damage evolution and failure strength (tension and torsion) of carbon fiber-reinforced epoxy matrix (CFRP) laminates. Hashin’s damage criteria were utilized to monitor the evolution of multi-damage modes, and FEM simulations were also performed by using the ABAQUS code to clarify the specific damage modes in detail as an instructive complement. The failure characteristics of all the notched samples were analyzed and compared with those without notches. The measured results presented that the existence of a variety of notches significantly impaired the load carrying capacity of CFRP laminates. The tensile strengths of C-notch and U-notch increase with an increasing notch radius, while the ultimate torques of C-notch and V-notch decrease with an increasing notch size and angle. The variation in notched properties was explained by different notch shapes and sizes, and the failure characteristics were also presented and compared among notched CFRP laminates with varied notches.

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“…However, due to the fatigue size effect, 2 the fatigue life of notches is limited by notch opening angle, notch radius, and notch depth. The influence of size effect on fatigue has been evaluated through some experimental and numerical studies; for instance, critical distance theories and stress gradient were applied to predict fatigue life of samples with different depths and root radii 3–5 . The relationship between fatigue life and fatigue region can be well described by correlating with the notch depth based on stress field intensity approach 6 .…”

Section: Introductionmentioning

confidence: 99%

“…The influence of size effect on fatigue has been evaluated through some experimental and numerical studies; for instance, critical distance theories and stress gradient were applied to predict fatigue life of samples with different depths and root radii. [3][4][5] The relationship between fatigue life and fatigue region can be well described by correlating with the notch depth based on stress field intensity approach. 6 With the aim to study the effects of notch size on the fracture behavior of the specimens, different hole radii were analyzed through finite fracture mechanics theory.…”

Section: Introductionmentioning

confidence: 99%

Data‐driven approach to design fatigue‐resistant notched structures

Wang

Gao

Berto

2022

Fatigue Fract Eng Mat Struct

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Fatigue is the most common failure mode for engineering materials in various industrial applications. Generally, designing new products and components based on typical deterministic fatigue design approaches is slow and expensive. Although numerous investigations have been carried on this topic over decades, there still lacks a robust and efficient method to design a super‐fatigue‐resistant and testless structure. In this investigation, a novel data‐driven approach based on the deep learning algorithm is applied on designing a fatigue‐resistant notched structure under different loading via numerical simulations and deep learning. The notches with various shapes are designed by employing the same material. Then finite element (FE) simulations are performed to obtain the mechanical behaviors of notched structures under different loading conditions. The deep learning algorithm is applied to predict mechanical behaviors of unknown notched structures based on input training set of simple notched geometries and relative lower computational cost. It is demonstrated that deep learning on the fatigue‐resistant structure is a promising approach of fatigue design. This work offers an alternative design strategy of fatigue‐resistant structure and cost‐effective solution to accelerate the design of engineering components under different loading conditions.

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Using the theory of critical distances to predict notch effects in fibre composites

Cited by 9 publications

References 21 publications

The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

Notched Behaviors of Carbon Fiber-Reinforced Epoxy Matrix Composite Laminates: Predictions and Experiments

Data‐driven approach to design fatigue‐resistant notched structures

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