scholarly journals A Novel and Highly Effective Natural Vibration Modal Analysis to Predict Nominal Strength of Open Hole Glass Fiber Reinforced Polymer Composites Structure

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1251
Author(s):  
Mohammed Y. Abdellah ◽  
Mohamed K. Hassan ◽  
Ahmed F. Mohamed ◽  
Khalil Abdelrazek Khalil
Keyword(s):  
Size Effect ◽  
Modal Analysis ◽  
Composite Laminates ◽  
Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Nominal Strength ◽  
Open Hole ◽  
Vibration Modal ◽  
Non Destructive

Glass fiber reinforced polymer (GFRP) composite laminates are considered the key material in many industries such as the infrastructure industries and the aerospace sector, and in building structures due to their superior specific strength and lightweight properties. The prediction of specimens’ nominal strength with open holes is still an attractive and questionable field of study. The specimen size effect is referred to its strength degradation due to the presence of holes when specimen geometry gets scaled. The non-destructive test used to measure the nominal strength of such material is a great tool for fast selection purposes, but not secure enough for several purposes. Furthermore, the destructive tests which are more expensive and time-consuming should be avoided in such structures. The present work aims to predict the nominal strength of open-hole GFRP’s composite using modal analysis of their natural frequency as non-destructive tests. At this end, the natural frequency, which is measured using modal analysis procedures, is combined with both linear elastic fracture mechanics (LEFM) and the theory of elasticity to predict the nominal strength of open-hole composite laminates. This advanced model employs two parameters of surface release energy resulting from a simple tension test and Young’s modulus based on vibration modal analysis. It is well established that these types of materials are also subjected to a size effect in dynamic response. Inversely to the known static loading size effect, the size effect in dynamic response increases with specimen size. The novel model gives excellent and acceptable results when compared with experimental and finite element ones. Size effects curves of a nominal strength of these laminates have a very close relative value with those obtained from finite element and analytical modeling. Moreover, the received design tables and graphs would be highly applicable when selecting suitable materials for similar industrial applications.

EFFECT OF HYBRIDIZATION ON OPEN-HOLE TENSION PROPERTIES OF WOVEN KEVLAR/GLASS FIBER HYBRID COMPOSITE LAMINATES

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Norazean Shaari ◽  
Aidah Jumahat ◽  
Shahrul Azam Abdullah ◽  
Ahmad Zariff Hadderi
Keyword(s):  
Tensile Strength ◽  
Glass Fiber ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Open Hole ◽  
Strength And Stiffness

Hybrid laminates consisting of woven Kevlar/glass fiber composite plies were studied in terms of their residual tensile strength, stiffness and fracture surface.  Residual tensile strength and stiffness were determined from the open hole tension test according to ASTM D5766. The laminates of Kevlar fiber reinforced polymer (KFRP), glass fiber reinforced polymer (GFRP) and hybrid of Kevlar-glass fiber reinforced polymer (KGFRP) were fabricated using a vacuum bagging process. Three different ratios of Kevlar to glass fiber plies were prepared in this study which were 20:80, 50:50, and 80:20. Results showed that hybrid laminate consisting of 80:20 Kevlar to glass fiber plies, produced higher residual tensile strength and stiffness when compared to the other hybrid system. Furthermore, strength and stiffness of hole specimens were reduced within 50-63% when compared to unhole specimens due to existence of the hole. In addition, the effect of adding nanosilica to the hybrid system was also studied. 5 wt% of nanosilica was added to the hybrid composite laminates and results showed that higher tensile strength and stiffness was observed in GFRP and 20:80 KGFRP specimens, while the tensile strength was decreased with an increased number of Kevlar fiber. This research was conducted as there are limited number of studies that have been done on the tensile strength of woven hybrid composite laminates so far, especially on hybridization of Kevlar and glass fiber with consideration on the effect of hole and addition of nanofillers.

Ultra-violet health monitoring of smart composite laminate using embedded fiber Bragg grating sensors

2020 ◽  
Vol 54 (22) ◽  
pp. 3143-3158 ◽  
Author(s):  
S Mohanta ◽  
Y Padarthi ◽  
S Chokkapu ◽  
J Gupta ◽  
S Neogi
Keyword(s):  
Health Monitoring ◽  
Composite Laminate ◽  
Matrix Material ◽  
Ultra Violet ◽  
Fiber Reinforced Polymer ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Non Destructive ◽  
Strength Retention

A novel approach is developed to evaluate the property retention on prolonged ultra-violet exposure and hence, health monitoring of glass fiber reinforced polymer composite laminate. This is achieved in a non-destructive manner by mapping the strength retention with the established strain. Embedded fiber Bragg grating sensor and strain gauges are employed to monitor the strain evolution within the laminate. Tensile and flexural tests are conducted at regular intervals to estimate the mechanical strength retention with varying duration of ultra-violet exposure. Through this analysis, it is observed that the property degradation mechanism follows the first-order reaction kinetics. The degradation of matrix material along with the stress relaxation over time develops the stress–strain fields near the interfaces of matrix and fiber. Moreover, the established strain is interpreted by formulating the model that considers the unifying influence of stress relaxation and chemical degradation. This model has closely (R2 = 0.9810 and 0.9790) predicted the experimental data of strain than the existing ones (R2 = 0.9142 and 0.9119). Besides, property retention is mapped with the predicted strain. More importantly, FESEM and FTIR confirm the fact that ultra-violet radiation degrades the matrix material, and thus the mechanical property gets significantly deteriorated. This suggests that the strain measurement is an effective, non-destructive and health monitoring technique to assess the property degradation of the manufactured glass fiber reinforced polymer composites.

An approximate analytical model for modification of size effect law for open-hole composite structure under biaxial load

2020 ◽  
pp. 095440622095937
Author(s):  
Mohammed Y Abdellah
Keyword(s):  
Size Effect ◽  
Composite Laminates ◽  
Approximate Model ◽  
Biaxial Stress ◽  
Damage Initiation ◽  
Main Challenge ◽  
Nominal Strength ◽  
Biaxial Stress State ◽  
Cohesive Laws ◽  
Open Hole

Nominal strength prediction remains the main challenge in the field of design and manufacturing of composite laminates. An approximate model to study the stress distribution around a circular hole in composite laminates is derived in this study. This model is constructed using well-known cohesive zone models and mainly depends on the un-notch strength and in-plane fracture toughness. The model attempts to modify and extend the specimen size effect curves, extracted using two-parameter cohesive laws (linear, exponential, and constant), into a biaxial stress state. It successfully predicts the damage initiation, propagation, and fracture of multidirectional composite laminates. Moreover, the stress concentration factor for a composite plate under varying biaxiality is calculated.

scholarly journals Numerical and Experimental Investigation of the Through-Thickness Strength Properties of Woven Glass Fiber Reinforced Polymer Composite Laminates under Combined Tensile and Shear Loading

2020 ◽  
Vol 4 (3) ◽  
pp. 112
Author(s):  
Teruyoshi Kanno ◽  
Hiroki Kurita ◽  
Masashi Suzuki ◽  
Hitoshi Tamura ◽  
Fumio Narita
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Strength Properties ◽  
Shear Loading ◽  
Fiber Reinforced Polymer ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Gfrp Composite ◽  
Woven Glass Fiber

The purpose of this paper is to investigate the through-thickness stresses of woven glass fiber reinforced polymer (GFRP) composite laminates under combined tensile and shear loading. Tensile tests were carried out with cross specimens at room temperature under various stacking angles, and the through-thickness strength properties of the woven GFRP laminates were evaluated. The failure characteristics of the woven GFRP laminates were also studied by optical microscopy observations. A three-dimensional finite element analysis (FEA) was carried out to calculate the stress distributions in the cross specimens, and the failure conditions of the specimens were examined. The numerically determined interlaminar tensile and shear stresses at failure location were consistent with Hoffman and Mohr-Coulomb failure criteria when the stacking angle was relatively small. This work is the first attempt to quantify the relation between interlaminar tensile and shear strengths of GFRP composite laminates under tensile and shear loading simultaneously using a combined numerical and experimental approach. A method based on finite element stress analysis was developed for estimating the through-thickness strength of the composite laminates using the experimentally determined fracture load and location. The results suggest that the through-thickness strength under combined tensile and shear loading can be determined effectively by this approach for relatively small stacking angles.

scholarly journals Error Analysis of Non-Destructive Ultrasonic Testing of Glass Fiber-Reinforced Polymer Hull Plates

2021 ◽  
Vol 5 (9) ◽  
pp. 238
Author(s):  
Zhiqiang Han ◽  
Jaewon Jang ◽  
Sang-Gyu Lee ◽  
Dongkun Lee ◽  
Daekyun Oh
Keyword(s):  
Glass Fiber ◽  
Ultrasonic Testing ◽  
Fiber Reinforced Polymer ◽  
Design Parameters ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Thickness Variations ◽  
Non Destructive

Glass fiber-reinforced polymer (GFRP) ship structures are generally fabricated by hand lay-up; thus, the environmental factors and worker proficiency influence the fabrication process and presence of error in the non-destructive evaluation results. In this study, the ultrasonic testing of GFRP hull plate prototypes was conducted to investigate the statistical significance of the influences of the design parameters, e.g., the glass fiber weight fraction (Gc) and thickness variations, on the measurement error. The GFRP hull plate prototypes were fitted with E-glass fiber chopped strand mats (40 wt % content) with different thicknesses (7.72 mm, 14.63 mm, and 18.24 mm). The errors in the thickness measurements were investigated by conducting pulse-echo ultrasonic A-scan. The thickness variation resulted in increased error. Furthermore, hull plate burn-off tests were conducted to investigate the fabrication qualities. Defects such as voids did not have a significant influence on the results. The statistical analysis of the measurement errors confirmed that the thickness variations resulted in a strong ultrasonic interference between the hull plates, although the hull plates had similar specific gravity values. Therefore, the ultrasonic interference of the layer group interface should be considered to decrease the GFRP hull NDE errors with respect to an increase in the thickness and Gc.

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