in this paper a new method for nondestructive testing or nondestructive evaluation is proposed for glass-epoxy composite. for this purpose, impact-echo is used to evaluate the properties of composite materials, detecting internal defects and thickness measurement. in the impact-echo method a steel ball impacts on a composite plate and generates stress waves or p-waves which will be transferred ...

Isotropic ultra-thin shells or membranes, as well cable–membrane structures, cannot resist loads at the initial state and always require a form-finding process to reach steady state. After this stage, they can work in pure membrane quickly experience large deflection behavior, even with small amplitude of load. This paper aims improve load-carrying capacity strength structures via exploiting ad...

The existing experimental evidence suggests that organic matrix composites sustain less impact damage when an electric field is applied. The intricate interaction of an electrical field and mechanical load is governed by coupling of the mechanical and electromagnetic fields via the Lorentz force as well as by the processes undergoing at the microscopic level: Joule heat, fiber-matrix interface ...

BACKGROUND Most military helmets are designed to prevent penetration by small firearms using composite materials in their construction. However, the transient deformation of the composite helmet during a non penetrating impact may result in severe head injury. METHOD Two experimental designs were undertaken to characterize the extend of injuries imparted by composite panels using in protectiv...

This study discusses a structural health monitoring (SHM) system developed to detect the presence of delamination, and predict its location and size in a composite structure. Two structures are considered in this study: a composite beam and a T-joint structure used in ships. Finite element (FE) models of these structures are created, embedded with delaminations, and the strain distribution alon...

This paper discusses a Real-Time Structural Health Monitoring (SHM) technique developed to predict the presence and extent of multiple delaminations in a composite structure. This technique was developed integrating Artificial Neural Networks (ANN) and the Damage Relativity Analysis Technique (DRAT). This SHM technique uses strain signatures emanating from the surface of the structure as damage...

ABSTRACT: Aqueous enzymatic extraction of oil from pistacia khinjuk was performed using cellulase. The central composite design was used to optimize the parameters that are significant to the process. The influence of three regressors on the percentage of oil recovery from seed was evaluated using second-order polynomial multiple regression model. Analysis of variance showed a high coefficient ...

A transform-domain ultrasonic pulse-echo signal processing technique was developed to determine the locations of delaminations in thin composite laminates. It was shown in this study that complex and magnitude cepstra can be used as effective tools for detecting reflected echoes and reconstructing high-resolution images. The scheme was experimentally verified by detecting the echo arrival times...