Papers by Keyword: Honeycomb Sandwich Structure

Abstract: Honeycomb composite structures widely used in aviation are sturdy and light-weight but they may accumulate water from the atmosphere during aircraft operation. The presence of water in honeycomb cells leads to a higher airplane mass and excessive corrosion of aluminum cores, while the frozen water endangers panel integrity. This work describes the use of infrared thermography for detecting water trapped in aviation honeycomb cells.

Abstract: In this paper, a honeycomb sandwich beam and a plate are studied to verify a method of determining the equivalent properties of these structures. The responses of the structures are obtained from both numerical and physical experiments considering free-free boundary conditions. It is shown that a double-layer effect caused by the bonding-stretching process during manufacturing cannot be ignored. It is also found that at low frequencies, the equivalent method gives good agreement with measurements. However at higher frequency range, the response calculated using equivalent method shift towards higher frequency compared with measurements.

Abstract: continuous carbon fiber reinforced silicon carbide (C_f/SiC) ceramic matrix composites were prepared by precursor infiltration pyrolysis and chemical vapor infiltration (PIP-CVI process), in which the honeycomb sandwich structure preforms were fabricated by the three dimensional braid method. In this paper, the microstructure and the bending strength were observed and analyzed by SEM and three point bending method. The results of the study show that: The C_f/SiC ceramic matrix composites, which were lightweight and high strength, were prepared by that technique. The composite samples have a fiber volume fraction of 20%, a density of 0.38 g/cm³ and a flexural strength of 3.81 MPa. The honeycomb sandwich fiber reinforced ceramic matrix composite with a light weight, corrosion resistance and excellent physical and mechanical properties is a kind of structure and functional ceramic materials, which can realize the structure and the requirement of heat integration.

Abstract: Based on the honeycomb sandwich structure on the supported plates of a satellite antenna, the bending effect of the honeycomb sandwich structure is analyzed with analytical method and finite element method (FEM) to design and verify the models established in the paper. Then, the analytical method without/with considering the flexural rigidity effect of the face sheets is solved. And the equivalent model of the honeycomb sandwich structure is constructed for valuating analysis. Then the three different models are analyzed with finite element method. The results show that, the flexural rigidity of face sheets can affect the bending of the structure when the thickness cant be ignored. Compared to the reality model, the bending results of the equivalent model are more conservative. Its significant in the engineering practice for the honeycomb sandwich structures.

Abstract: In this paper, the failure modes of the honeycomb sandwich structure under uniaxial compressions after impact (CAI) are analyzed through experiments and Finite Element Method (FEM). Three cases of impact damage location, two cases of impact damage depth and adhesive properties are investigated by the comparisons of corresponding non-destructive structure. Several conclusions are drawn: the failure modes and the initial damage positions obtained from experiments and FEM simulations are almost the same; the location of impact damage may affect the overall loading capabilities of the sandwich structure, whose decreasing rate peaks when the damage is at the top surface and drops when the damage is at the marginal area; different adhesive layer property of interface may lead to the failure mode change, that is, instead of honeycomb core failure, interlaminar failure will occur when the fracture energy of the adhesive layer is low; the damage level and risky location of the structure will vary relevant to the impact energy.

Abstract: In order to analyze the mechanical properties of Carbon/epoxy facings-Aluminum honeycomb sandwich structure, we simulated panels of different layers and core thickness using ABAQUS finite element analysis program. And three-point bending tests and shear tests were made on the same panels using electronic universal testing machine. In addition, we also made the same three-point bending tests on steel tubes to get a comparison with honeycomb sandwich panels. It could be seen that, the simulated results were basically identified with experimental results. The results indicated that core thickness played an important role in the panels’ bulking modulus, and number of carbon fiber layers decided the shear strength. As a whole, honeycomb sandwich structure was suitable for use in the car body with good mechanical properties under premise of lighter.

Abstract: To estimate the disbond defects of the carbon fiber composite materials with honeycomb sandwich structure applied in the aerospace, active infrared thermographic NDT (non-destructive testing) is researched. The specimen with known disbond defects is detected by an active infrared thermography system. The specimen is stimulated by a pulse heating source. Based on the thermal wave propagation theory, the surface temperature of the specimen contained defects will differ from the surrounding sound area because of their different thermal-physical properties. The surface temperature is monitored using infrared camera and analyzed by a computer in the time domain. The experiment results show that the active infrared thermographic NDT is rapid, effective and intuitive for detecting the disbond defects in composite materials with honeycomb sandwich structure.

Abstract: The concept of light weight design will be very helpful for the tilting train to travel around a curve at a faster speed because the light weight car body makes the center of gravity lower. The impact characteristics of composite materials should be investigated because the impact property of composites is very important. This paper investigates the low-velocity impact characteristics and residual strength conducted on honeycomb sandwich panels. Low-velocity impact tests were carried out at different energy levels on honeycomb sandwich panels using a drop-weight apparatus. The impact-induced damages such as fiber breakage, matrix crack and delamination are examined with an optical microscope apparatus. Residual strength was evaluated by applying three point bending load to honeycomb sandwich panels. Experimental results show that the residual strength is greatly reduced as the impact energy increases. From the microscopic observation data, matrix crack, fiber breakage and delamination are the main impact damages of honeycomb sandwich panels.

Abstract: To prove the suitability the honeycomb composites structure with VARTM, the mechanical properties of the skin materials and honeycomb composites structure were evaluated with the static strength tests. The mechanical properties of honeycomb composites structure made by VARTM were satisfied with the real using conditions instead of the composites structure made by autoclave process. Accordingly, the honeycomb sandwich composites made by VARTM is available for manufacturing various composites parts. VARTM was very effective method to manufacture the honeycomb sandwich composites. It was possible that the manufacturing process was changed from autoclave process to VARTM to solve the problems on the autoclave process.