Fiber Reinforced Plastic Plates Research Articles

Buckling of laminated plates containing delaminations

The stability behaviour of fibre reinforced plastic plates containing delaminations is studied. Embedded delaminations in the form of a circle or an ellipse, centrally located in [0/90 2/0] square plates are considered. A 36 degrees of freedom triangular finite element based on classical laminated plate theory is utilized to idealize the two sublaminates in the delaminated and the undelaminated part of the laminate. Results are compared with some of those available in the literature. Effects of size, shape, thickness-wise location of delamination and fibre orientation on the buckling load are discussed. Generally, the buckling load reduces with increase in delamination size and three distinct types of buckling modes are possible depending upon the delamination parameters.

External Reinforcement of Concrete Beams Using Fiber Reinforced Plastics

A series of 16 under-reinforced beams was tested to study the effectiveness of external strengthening using fiber reinforced plastic (FRP) plates. Plates of glass, carbon and aramid fibers were bonded to the tension side of the beams using a 2-part epoxy. An interative analytical method was developed to predict the stiffness and maximum strength in bending of the plated beam. Increases in stiffness (over the working load range) from 17 to 99 percent and increases in strength (ultimate) from 40 to 97% were achieved for the beams with FRP plates. Predicted and acutal load-deflection curves showed fairly good agreement, although generally the theoretical curves were stiffer. Experimental failure did not occur in the maximum moment region on many of the beams, despite attempts at end anchorages to postpone local shear failure. The ulltimate loads of the beams that did fail in the maximum region were within about 5% of predicted values.

Ion beam assisted deposition of a thin film coating on a gradient-index lens array

A new coating method which employs ion bombardment has been developed for a gradient-index (GRIN) rod lens array using silicone rubber and fiber reinforced plastic plates in its construction. The thin film coatings deposited using this method passed the durability tests on the basis of MIL-M-13508C. The adhesion of the thin film coating was strong and durable enough to allow for use on GRIN rod lens arrays in photocopiers. The effect of ion bombardment has been investigated with thin film analysis data by Fourier transform infrared microspectroscopy and secondary ion mass spectrometry.

The finite element technique for predicting the natural frequencies, mode shapes and damping values of filamentary composite plates

This article presents the numerical method for predicting the natural frequencies, mode shapes and damping values of filamentary composite plates. This method is based on finite element technique, using damped element and allowing transverse shear deformation. For the example of this technique, the theoretical results comparing with experimental values of carbon fibre and glass fibre reinforced plastics plates (mid-plane symmetric) are provided. The dynamic properties of these laminates are discussed. Finally, a simple graphic technique to estimate the natural frequencies and damping values is suggested.

Prediction and Measurement of the Vibrational Damping Parameters of Carbon and Glass Fibre-Reinforced Plastics Plates

The objective of this investigation is to predict the natural frequency and specific damping capacity of laminated composite plates in various modes of vibration by using the finite element method.

PREDICTION AND MEASUREMENT OF THE NATURAL FREQUENCIES AND DAMPING CAPACITY OF CARBON FIBRE-REINFORCED PLASTICS PLATES

The objective of this investigation is to predict the natural frequency and specific damping capacity of laminated composite plates in various modes of vibration by using the finite element method. The simple definition of specific damping capacity is ψ = ƊU/U, where U is the maximum strain energy stored per cycle and U is the energy dissipated per cycle. In this work, U is calculated by a finite element method which includes transverse shear deformation ; ƊU is determined from a damped element model. The specific damping capacities, mode shapes, and natural frequencies of various free-free carbon and glass fibre-reinforced plastics plates have been predicted and measured.

Effect of moisture and glass contents on the poisson's ration of FRP plates as determined by laser interferometry

Poisson's ratio values of orthotropic FRP (Fibre Reinforced Plastics) plates were determined using the laser interferometry technique. The variation of Poisson's ratio was measured as a function of moisture content and glass fibre content (both in percentage weight) in the FRP plates, using this technique. The holographic test set up specifically fabricated to make the above measurements is described in the paper. Poisson's ratio of these composite plates increased as their moisture content increased and decreased as the fibre loading increased. It was concluded that the laser interferometry technique offered a very useful and reliable tool to determine the Poisson's ratio of orthotropic FRP plates with varied compositions.

Torsional strength of carbon fibre reinforced composites for the application as internal bone plates

The paper is concerned with comparative measurements of torsional strength and modulus of carbon fibre reinforced composites in the form of plates as used for internal fixation of bones. The carbon/carbon-composites have been prepared with sulfur modified CT-pitch, phenolic resin and polyphenylacetylene resin as matrix precursor. Carbon fibre reinforced plastic plates were processed using commercially available prepregs. The mechanical properties and especially the torsional strength data are discussed from the view-point of requirements in osteo-synthesis.

Comparison of Single and Muilti-Hole Bolted Joints in Glass Fibre Reinforced Plastic

Data is presented on the strength of single and multi-hole joints in laminated glass fiber reinforced plastic plates bolted to a steel fitting. The laminate lay-up was (—45/0/—45/0°)s. The results suggest that the joint strength, expressed as the load/bolt, decreases as the joint geometry be comes increasingly complex.

Acoustic emission detection using a piezoelectric strain gauge for failure mechanism identification in cfrp

An experimental technique for monitoring the fatigue of carbon fibre-reinforced plastics plates is described. The technique is based upon the use of a piezoelectric strain gauge for acoustic emission detection. Count rate and spectral analysis procedures may be used in the analysis of the measured signals and their application for the characterisation of failure mechanisms is demonstrated. Results from flexural tests on a series of multi-layered plates with various lay-ups show that the observations based on acoustic emission detection correlated well with data from other complementary monitoring methods, such as ultrasonic scanning. The main type of fatigue damage observed was delamination.

The Effect of Stacking Sequence on the Pin-Bearing Strength in Glass Fibre Reinforced Plastic

The pin-bearing strength of glass fibre reinforced plastic plates was measured using specimens possessing mid-plane symmetry and composed of eight layers, two each at 0° , 90° , and ±45° . The results suggest that placing the 90° layer (normal to the applied load) at or next to the surface increases the bearing strength. The ultimate failure mode was found to depend on stacking sequence.