Authors: Roberta Licheri, Roberto Orrù, Antonio Mario Locci, Giacomo Cao
Abstract: Two processing routes, both starting from powders of Zr, B4C and Si, which take advantage of
the Spark Plasma Sintering (SPS) apparatus, are proposed in this work for the preparation of fully dense
2ZrB2-SiC composite. The first method consists of the in-situ reaction synthesis and densification of the
product while, in the second one, reactants are first converted by SHS (Self-propagating Hightemperature
Synthesis) into the desired composite and the obtained powders are then sintered by SPS.
Based on the results reported in this work, both routes are particularly convenient as compared to the
techniques available in the literature for the preparation of analogous materials.
Authors: Jeong Pyo Nam, Sung Ho Yoon, Young Eun Hwang, Hong Li, Qing Fen Li
Abstract: In this study, the effect of combined environmental factors such as ultraviolet ray, high
temperature and high moisture on mechanical and thermal analysis properties of glass fabric and
phenolic composites are evaluated through a 2.5KW accelerated environmental aging tester. The
environmental factors such as temperature, moisture and ultraviolet ray applied of specimens. A
xenon-arc lamp is utilized for ultraviolet light and exposure time of up to 3000 hours are applied.
Several types of specimens - tensile, bending, and shear specimens that are warp direction and fill
direction are used to investigate the effects of environmental factors on mechanical properties of the
composites. Mechanical degradations for tensile, bending and shear properties are evaluated
through a Universal Testing Machine (UTM). Also, storage shear modulus, loss shear modulus and
tan δ are measured as a function of exposure time through a Dynamic Mechanical Analyzer (DMA).
From the experimental results, changes in material properties of glass fabric and phenolic
composites are shown to be slightly degraded due to combined environmental effects.
Authors: Jiang Tao Ruan, Shi Bin Wang, Jing Wei Tong, Min Shen, Francesco Aymerich, Pierluigi Priolo
Abstract: The results on a numerical and experimental study of graphite/epoxy composite plates [03/903]S are presented. Each specimen was firstly impacted by the low velocity with different energy level. Compression experiment based on carrier electronic speckle pattern interferometry (carrier-ESPI) is made for the post-impact composite plate. The finite element method (FEM) is used to gain further understanding of the deformation behavior of impacted specimens. The compressive deformation of various delaminated composite plates are analyzed with software ANSYS to see that the impact parameters and delamination damage data, such as impact energy, maximum impact force and delamination area, affect the deformation fields. In addition, the comparisons between the finite element results and experimental measurements are considered under different compression loads.
Authors: Łukasz Pieczonka, Andrzej Klepka, Wieslaw Jerzy Staszewski, Tadeusz Uhl, Francesco Aymerich
Abstract: The paper investigates experimentally the effect of low-frequency vibration on nonlinear vibro-acoustic wave modulations applied to the detection of Barely Visible Impact Damage (BVID) in a composite plate. Finite Element (FE) modeling was used in a pretest stage to identify different motion scenarios of delaminated surfaces and relate them to natural frequencies of the damaged plate. In particular the opening-closing and frictional sliding actions of the defected interfaces have been considered. Subsequently, the identified frequencies have been used for low frequency excitation in nonlinear acoustic experiments on a composite plate with impact damage.
Authors: Marcin Strączkiewicz, Andrzej Klepka, Wieslaw Jerzy Staszewski, Francesco Aymerich
Abstract: Over the last few decades a number of different techniques have been developed for impact damage detection in composite structures. The most frequently used methods in Non-Destructive Testing (NDT) are: ultrasonic testing, acoustics emission, X-ray and visual inspection. These methods are quite effective but often require expensive equipment, a large number of transducers or highly qualified staff. Additionally, these techniques are used locally. Therefore monitoring of large structures in many cases is very difficult or even impossible. Recent years have seen many new developments mostly free from these limitations. This paper investigates the triple correlation technique for impact damage detection in composite structures. The method correlates fundamental and higher harmonics of signal vibration response