Circuit models for Salisbury screens made from unidirectional carbon fiber composite sandwich structures

2016 ◽  
Author(s):  
Elliot J. Riley ◽  
Erik H. Lenzing ◽  
Ram M. Narayanan
2014 ◽  
Vol 108 ◽  
pp. 234-242 ◽  
Author(s):  
Jian Xiong ◽  
Li Ma ◽  
Ariel Stocchi ◽  
Jinshui Yang ◽  
Linzhi Wu ◽  
...  

2010 ◽  
Vol 29-32 ◽  
pp. 2256-2261 ◽  
Author(s):  
Jun Li ◽  
Ba Ta Xi

This note presents the main process of optimization design of foam core/carbon fiber composite sandwich which primarily designed for UAV wing beams. During the actual application, the original design provided excessive structural strength and it has certain capacity to be optimized. So the weight of structure can be reduced under the premise of meet the strength requirement. In order to characterize fully the complex mechanical behavior of such a highly heterogeneous material and find the ultimate strength of this structure, MSC.Patran/Nastran has be applied on analysis of this composite sandwich structure. Base on the result of the numerical simulations, the best combination of composite laminated and the material layer thickness have be determined, and the beams structure of the lightweight has be designed ultimately.


Author(s):  
Mehmet Ziya Okur ◽  
Serkan Kangal ◽  
Metin Tanoğlu

Lightweight composite sandwich structures are laminated composite structures that are composed of thin stiff face sheets bonded to a thicker lightweight core in between. These structures have high potential to be used in marine, aerospace, defense and civil engineering applications due to their high strength to weight ratios and energy absorption capacity.In this study, composite sandwich structures were developed with carbon fiber reinforced polymer composite face sheets and aluminum honeycomb core materials with various thicknesses. Carbon fiber/epoxy composite face sheets were fabricated with lamination of [0/90]s carbon fabrics by vacuum infusion technique. Al honeycomb layers were sandwiched together with the face sheets using a thermosetting adhesive. Mechanical tests were carried out to determine the mechanical behavior of face sheets, Al cores and the composite structure. Effect of core thickness on the mechanical properties of the sandwich was investigated.


2011 ◽  
Vol 194-196 ◽  
pp. 117-120 ◽  
Author(s):  
Xai Mei Lu ◽  
Yun Fei Ma ◽  
Shi Xun Wang

In this paper, low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures are investigated experimentally and numerically. Low-velocity impact tests and residual tensile strength tests are simulated by the FE (finite element) software, ABAQUS/Explicit and its subroutine (VUMAT). In order to give more detailed description about the impact damage of the structure and improve modeling accuracy, multi-steps analysis method is employed to simulate impact process and residual tensile strength test in one analysis model. The calculation results computed by the FE model have been compared to the value of experiments, the difference of impact process simulation is about 3.3% and that of tensile strength test simulation is about 12.9%. The calculation error of computation model is acceptable, since unavoidable damage could be introduced in the courses of manufacture, processing and transportation of composite materials, and these damages are determinated difficultly in the computation programs. Next, the degradation tendency chart of residual tensile strength and impact energy threshold Uo of carbon fiber composite lattice core sandwich structures are obtained by the computation value of residual tensile strength after impacted with different impact energy. Previously, this threshold can only be obtained by experiment tests. After the contact force which is bigger than the threshold Uo impact on the sandwich structures, the residual tensile strength of structures are degraded greatly. This conclusion is significant for the design and application of carbon fiber composite lattice core sandwich structures.


Author(s):  
Hari P. Konka ◽  
M. A. Wahab ◽  
K. Lian

The smart sandwich structures have been widely used in the aerospace, automobile, marine, and civil engineering applications. A typical smart sandwich structure is usually comprised of two stiff face skins separated by a thick core with variety of embedded sensors to monitor the performance of the structures. In this study, the smart composite sandwich structure (CSS) samples are fabricated with glass microballoons syntactic foam core and resin infused glass-fiber face skins (with piezoelectric fiber composite sensors (PFCS) embedded inside the resin infused glass-fiber face skins). One of the main concerns associated with embedding sensors inside composite structures is the structural continuity, compatibility, and interface stress concentrations caused by the significant differences in material property between sensor and host structures. PFCS are highly flexible, easily embeddable, highly compatible with composite structures and their manufacturing processes, which makes them ideal for composite health monitoring applications. In this study, in-plane tensile, tension–tension fatigue, short beam shear, and flexural tests are performed to evaluate the effect on strengths/behavior of the CSS samples due to embedded PFCS. Then carefully planned experiments are conducted to investigate the ability of the embedded PFCS to monitor the stress/strain levels and detect damages in CSS using modal analysis technique. The tensile tests show that both the average ultimate strength and the modulus of elasticity of the tested laminate with or without embedded PFCS are within 7% of each other. The stress–life (S-N) curves obtained from fatigue tests indicates that the fatigue lives and strengths with and without the PFCS are close to each other as well. From short beam and flexural test results, it is observed that embedded PFCS leads to a reduction of 5.4% in the short beam strength and 3.6% in flexural strength. Embedded PFCS’s voltage output response under tension–tension fatigue loading conditions has been recorded simultaneously to study their ability to detect the changes in input loading conditions. A linear relationship has been observed between the changes in the output voltage response of the sensor and changes in the input stress amplitude. This means that by constantly monitoring the output response of the embedded PFCS, one could effectively monitor the magnitude of stress/strain acting on the structure. Experiments are also performed to explore the ability of the embedded PFCS to detect the damages in the structures using modal analysis technique. Results from these experiments show that the PFCS are effective in detecting the initiations of damages like delamination inside these composite sandwich structures through changes in natural frequency modes. Hence embedded PFCS could be an effective method to monitor the health of the composite sandwich structures’ in-service conditions.


2016 ◽  
Vol 156 ◽  
pp. 307-319 ◽  
Author(s):  
Jian Xiong ◽  
Lina Feng ◽  
Ranajay Ghosh ◽  
Huaping Wu ◽  
Linzhi Wu ◽  
...  

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