Papers by Keyword: Composite Structure

Abstract: It’s of great practical significance to improve the durability of steel-concrete composite beam structures.The deterioration of steel-concrete composite beams includes stud rust, reinforcement corrosion, corrosion of the steel beams and concrete performance degradation, which are caused by a number of factors. The corrosion mechanism of composite beams is discussed, and some basic issues remain to be solved in this area are analyzed in the paper. Besides, some research directions in the future are put forward.

Abstract: Reinforced Concrete Slab is one of the important types of composite structure, About the concrete laminated slab of the research and the engineering application are summarized, Point out that the characteristics of Composite Concrete Slabs, the application and development of the laminated slab of recent advances at home and abroad, and look into the future of the Composite Concrete Slabs research.

Abstract: Composite structures adopted in aerospace structures have attracted much interest to structural health monitoring (SHM) for localization of impact and damage positions due to their poor impact resistance properties. Propagation mechanism and frequency dispersion characteristics of Lamb wave signals on composite structures are more complicated than that on simple aluminum plates. Recently, much attention has been paid to the research of time reversal focusing method because this method shows a promising advantage to give a focusing image of the structural damage, improve the signal-to-noise ratio and compensate the dispersion of Lamb wave signals. In this paper, aiming at developing a practical method for on-line localization of impact and damage on aircraft composite structures which can take advantage of time reversal focusing and does not rely on the transfer function, a new phase synthesis based time reversal focusing method is proposed. Impact and damage images are given out directly through time reversal focusing based on phase synthesis process of the signals. A SHM demonstration system is built on a composite panel of an aircraft wing box with many bolt holes and stiffeners using the phase synthesis based time reversal focusing method. The demonstration results show that this method can estimate the positions of impact and damage efficiently with a low sensitivity of velocity errors.

Abstract: This paper presents ongoing work by the authors to implement real-time structural health monitoring (SHM) systems for operational research-scale wind turbine blades. The authors have been investigating and assessing the performance of several techniques for SHM of wind turbine blades using piezoelectric active sensors. Following a series of laboratory vibration and fatigue tests, these techniques are being implemented using embedded systems developed by the authors. These embedded systems are being deployed on operating wind turbine platforms, including a 20-meter rotor diameter turbine, located in Bushland, TX, and a 4.5-meter rotor diameter turbine, located in Los Alamos, NM. The SHM approach includes measurements over multiple frequency ranges, in which diffuse ultrasonic waves are excited and recorded using an active sensing system, and the blades global ambient vibration response is recorded using a passive sensing system. These dual measurement types provide a means of correlating the effect of potential damage to changes in the global structural behavior of the blade. In order to provide a backdrop for the sensors and systems currently installed in the field, recent damage detection results for laboratory-based wind turbine blade experiments are reviewed. Our recent and ongoing experimental platforms for field tests are described, and experimental results from these field tests are presented. LA-UR-12-24691.

Abstract: A new forming procedure was developed to produce shape memory composite structures having structural composite skins over a shape memory polymer core. Core material was obtained by solid state foaming of an epoxy polyester resin with remarkably shape memory properties. The composite skin consisted of a two-layer unidirectional thermoplastic composite (glass filled polypropylene). Skins were joined to the foamed core by hot compression without any adhesive: a very good adhesion was obtained as experimental tests confirmed. The structure of the foam core was investigated by means of computer axial tomography. Final shape memory composite panels were mechanically tested by three point bending before and after a shape memory step. This step consisted of a compression to reduce the panel thickness up to 60%. At the end of the bending test the panel shape was recovered by heating and a new memory step was performed with a higher thickness reduction. Memory steps were performed at room temperature and 120 °C so as to test the foam core in the glassy and rubbery state, respectively. Shape memory tests revealed the ability of the shape memory composite structures to recover the initial shape also after severe damaging (i.e. after room temperature compression). Compressing the panel at a temperature higher than the foam resin glass transition temperature minimally affects composite stiffness.

Abstract: This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed.

Abstract: The shear lag and shear deformation effects on deflection of composite girder with corrugated steel webs (CGCSW) was studied. The influence of shear lag and shear deformation effect was expressed by deflection coefficient δ1 and δ2. Parametric analysis within a scope of dimensions of built-in girders was performed, including girder span, width, height, thickness of concrete flange and thickness of steel web. The results show that the deflection coefficient of shear lag effect is approximately directly proportional to square of width-span ratio, while the deflection coefficient of shear deformation effect is related to all parameters. It’s suggested that shear lag effect on CGCSW’s deflection be neglected when width-span ratio is smaller than 1/9, and shear deformation effect should always be considered.

Abstract: In this paper the dynamic behavior of composite multilayered cylindrical panel with a single, square, interlaminar delamination is considered with using finite element method. Based on numerical results it is possible to determine the effect of the delamination on the guided wave propagation in curved structures. The results are used to quantify the difference of response signal in the case of perfect and defected structures. The results indicates that the size and orientations of the defect have a significant influence on overall dynamic behavior and they should be taken into account to design appropriate and effective non-destructive damage test methods and algorithms.

Abstract: The first part of the paper is devoted to presentation and discussion of the capabilities, advantages and limitations of infrared non-destructive techniques (IR NDT). Then, the results of experimental analysis performed by testing several specimens made of woven glass epoxy resin and containing artificial delamination in the form of square PTFE foil are presented.

Abstract: The paper presents the general review of application of composite materials including the distinction of their specific features. Also short overview of history of composite materials is conducted. The major subject is the explanation, what is advantage of the composites over traditional materials. Additionally, a lot of examples demonstrate in which areas of current industry they are applied.