Dynamic characteristics of sandwich composite with debonding

2018 ◽  
Vol 32 (9) ◽  
pp. 1204-1223
Author(s):  
M Idriss ◽  
A El Mahi
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Flexural Vibration ◽  
Experimental Tests ◽  
Core Material ◽  
Sandwich Composite ◽  
Dissipated Energy ◽  
Stress And Strain ◽  
Sandwich Composites ◽  
Modal Strain Energy

The article presents the results of experimental and finite element analyses of the flexural vibration behavior sandwich composite with different debonding ratios. Sandwich composite consists of two thin skins composed of E-glass fiber and epoxy resin bonded to lightweight and weaker core material of PVC foams. Experimental tests using the impulse technique were performed on the sandwich constituents and sandwich composites with different debonding lengths. The modal dynamic characteristics of sandwich composite were measured and discussed for each debonding ratio. A finite element modeling was used to determine the natural frequencies, modal shapes, and stress and strain fields for each element of sandwich composites for each debonding ratio. The modal strain energy approach was used to determine the contribution of energies dissipated of the core and the skins in the total dissipated energy and the global damping of the different sandwich composites. The results obtained by this approach are compared with those obtained experimentally.

Damage behavior of potting materials in sandwich composites with pinned joints

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Cesim Atas ◽  
Alper Basmaci
Keyword(s):  
Core Material ◽  
Sandwich Composite ◽  
Composite Panels ◽  
Sandwich Composites ◽  
Resin Infusion ◽  
Damage Behavior ◽  
Mechanical Joints ◽  
The Core ◽  
Bottom Face ◽  
Infusion Technique

AbstractThe damage behavior of the potting materials around a pinhole, being used in the mechanical joints of sandwich composites, is investigated experimentally. The sandwich composite panels used in the tests were manufactured by the vacuum-assisted resin infusion technique. Each of the top and bottom face sheets of the panels consisted of two woven E-glass/epoxy layers. As the core material, PVC foam (AIREX

MICRO-SLIP INDUCED DAMPING IN PLANAR CONTACT UNDER CONSTANT AND UNIFORM NORMAL STRESS

2010 ◽  
Vol 02 (02) ◽  
pp. 281-304 ◽  
Author(s):  
N. PEYRET ◽  
J.-L. DION ◽  
G. CHEVALLIER ◽  
P. ARGOUL
Keyword(s):  
Normal Stress ◽  
Loss Factor ◽  
Flexural Vibration ◽  
Bolted Joints ◽  
Stress Fields ◽  
Dissipated Energy ◽  
Stress And Strain ◽  
Loading Process ◽  
Nonlinear Loss ◽  
Planar Contact

The friction between interfaces at bolted joints plays a major role in the damping of structures. This paper deals with the energy losses caused by micro-slips in the joints. The aim of this study is to define in an analytical way these energy dissipation mechanisms which we examine through the analysis of a new benchmark: the flexural vibration of a clamped-clamped beam with original positioning of the interfaces. The joints exhibit the behavior of an interface under constant and uniform normal stress. The stress and strain values are computed at the joints under the assumption of quasi-static motion. This model allows us to understand the evolution of the slip and stick regions along the joint interfaces during the loading process. The expressions of the strain and stress fields during each phase of the loading process are derived. These lead to the quantification of the dissipated energy within the interface. Using this formula, a nonlinear loss factor can then be computed. In the final part of the paper, the dynamic response of the beam is calculated using this nonlinear loss factor.

The Theoretical Prediction and Experimental Verification of Modal Parameters for Carbon Fiber Reinforced Composites with Sandwich Structure

2011 ◽  
Vol 194-196 ◽  
pp. 2415-2419
Author(s):  
Guo Li Zhang ◽  
Ya Nan Wang ◽  
Jia Lu Li ◽  
Guang Wei Chen ◽  
Li Chen ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibre ◽  
Rectangular Plate ◽  
Natural Frequency ◽  
Flexural Vibration ◽  
Woven Fabric ◽  
Core Material ◽  
Sandwich Composite ◽  
Modal Shape ◽  
Modal Test

A innovative structure of sandwich composite rectangular plate with dimensions of 350 ×83.5×9.5mm was designed, it was made of unidirectional prepreg of carbon fibre and woven fabric prepreg of carbon fiber as face materials and paulownia as core material by hand lay-up performing and press molding technology for investigating the dynamic performance such as natural frequency and modal shapes. Based on testing the in-plane and out-plane mechanical properties of composite samples reinforced by unidirectional carbon fibre and carbon fiber woven fabric, a ANSYS FEA dynamic modeling was developed. According to the impulse response modal test method, a modal test system was established. The natural frequency test results showed that the minimum natural frequency of sandwich composite rectangular plate is about 616.45Hz which is higher about 27.5% than that of aluminum rectangular plate reinforced by carbon. The modal experiment indicated that the 1st modal shape, 2nd modal shape, 3rd modal shape and 4th modal shape of the sandwich composite rectangular plate were torsional vibration, flexural vibration shape, torsional flexural vibration and double-flexural vibration separately. It was found the calculating precision of FEA dynamic predication was very high, the dynamic predicating results by FEA could provide fundamental data to the optimal design high speed reciprocating sandwich composite rectangular parts.

Damage characterization of sandwich composites subjected to impact loading

2018 ◽  
Vol 22 (7) ◽  
pp. 2125-2138 ◽  
Author(s):  
Ranjith Kumar Pathipaka ◽  
Kiran Kumar Namala ◽  
Nagasrisaihari Sunkara ◽  
Chennakesava Rao Bandaru
Keyword(s):  
Contact Force ◽  
Impact Energy ◽  
Energy Levels ◽  
Free Fall ◽  
Core Material ◽  
Sandwich Composite ◽  
Sandwich Composites ◽  
Honeycomb Core ◽  
Advanced Composite Materials ◽  
3D Printed

Advanced composite materials are usually optimized to achieve balance of properties for given range of applications. In recent times, researchers had worked on the sandwich composites by using different foam and metal honeycomb as a core material. In the current project, honeycomb core is prepared by using 3D printed technology. In this case of sandwich composites, cross-linked polyethylene foam and 3D-printed polylactic acid honeycomb as core and GFRP is used as face sheet. The comparison is made between polyethylene foam and 3D printed honeycomb core sandwich composite in the aspect of toughness, strength, and modulus. The present study is to characterize the damages in the sandwich structure for the amount of energy absorbed by the structures such as delamination, indentation, crushing of foams, and debonding of face sheets and core material subjected to free fall impact. The contact force versus time, contact force versus deflection of plates with respect to impact energy levels of 9.3, 16.5, and 25.7 J and impact energy versus time are determined. The current research helps in determination of core materials effecting/absorbing the damage and behavior of sandwich materials subjected to impact loads.

DYNAMIC RESPONSE OF PHOTOPOLYMER RESINS CORES FOR NAVAL APPLICATIONS IN EXTREME ENVIRONMENTS

2021 ◽  
Author(s):  
ZACKERY NIETO ◽  
ALEJANDRA G. CASTELLANOS
Keyword(s):  
Finite Element ◽  
Fuel Efficiency ◽  
El Paso ◽  
Extreme Environments ◽  
Core Material ◽  
Sandwich Composite ◽  
Element Analysis ◽  
University Of Texas ◽  
Ice Caps ◽  
Arctic Temperature

Due to the melting of polar ice caps, large deposits of natural resources are becoming more readily available, leading to an increase in arctic naval exploration. Naval vessels and ship hulls must be built with lightweight structures, such as sandwich composites, to increase the ship’s fuel efficiency. However, identifying new material choices that can withstand the harsh Arctic environments is crucial for the survivability and safety of personnel and structures. This study investigates the potential of photopolymer resins through additive manufacturing as a lightweight sandwich composite core material. The thermo-mechanical properties of this resin were evaluated using: tensile, flexural, and compressive tests according to the ASTM Standards D638, D695, and D790, respectively. Tests were conducted at room temperature (23 C) and arctic temperature (-60 C). The experimental data will be used as an input for high-fidelity finite element (FE) simulations with the software ABAQUS. From the performed tests, the photopolymer exhibited isotropic behavior at both room (RT) and Arctic temperatures. Preliminary quasi-static results for “Durable Resin” at AT showed an increase of ~300% in its tensile, flexural, and compressive modulus and an increase of ~300% in its tensile and flexural strength and ~100% in its compressive strength when compared to the same resin at RT. The finite element analysis models showed good agreement with the experimental results. Zackery Nieto, The University of Texas at El Paso, 500 W. University Ave, El Paso,

Experimental Investigation on Dynamic Characteristics of Polypropylene Honeycomb Sandwich Structures under the Influences of Different Temperatures

2014 ◽  
Vol 606 ◽  
pp. 153-157
Author(s):  
P. Nagasankar ◽  
S. Balasivanandha Prabu ◽  
Velmurugan Ramachandran ◽  
R. Paskaramoorthy
Keyword(s):  
Experimental Investigation ◽  
Thermal Properties ◽  
Dynamic Characteristics ◽  
Loss Factor ◽  
Glass Fibers ◽  
Sandwich Composite ◽  
Sandwich Composites ◽  
Honeycomb Sandwich ◽  
Different Temperatures ◽  
Half Power

The dynamic characteristics of the Polypropylene honeycomb (PPHC) sandwich composites have been investigated under various temperatures (30°,35°,40°,45°,50°,55°,60°, 65°,70°,75° and 80°C) and different orientations (0° and 90°) of the glass fibers in the composites. Since the thermal properties of the constituent materials (glass fiber, epoxy resin and PPHC core) of the PPHC sandwich composites are different and the in-plane effect of the composites varies with the two different orientations (0° and 90°) of the fibers, the variation of the loss factor under the various temperatures are also different for these orientations. A two stage layup technique has been used to fabricate the sandwich composite specimens. Impulse technique associated with the half power bandwidth method, has been used to evaluate the natural frequency and damping values of the sandwich composite under different temperatures.

Tension and compression of sandwich composites with weft-knit fabric cores

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040004
Author(s):  
Jieng-Chiang Chen ◽  
Yi-Fang Zhuang
Keyword(s):  
Compressive Force ◽  
Core Layer ◽  
Longitudinal Force ◽  
Test System ◽  
Core Material ◽  
Sandwich Composite ◽  
Sandwich Composites ◽  
Carbon Fabric ◽  
The Core ◽  
Tension And Compression

The manufacturing techniques of sandwich composites containing core layers of weft-knit glass fabric (WG) and weft-knit carbon fabric (WC) with carbon fabric skin layers are discussed herein. The core layers of the sandwich composites were fabricated with WG-reinforced epoxy (E) resin, WC-reinforced epoxy resin, and polyurethane foam (F). The core layer was then stacked with two pieces of carbon fabric on the top and bottom surfaces to fabricate the sandwich composites. Three sandwich composites [plain carbon fabric sandwich composite with a WG core layer (C/E/WG), plain carbon fabric sandwich composite with a WC core layer (C/E/WC), and plain carbon fabric sandwich composite with an F core layer (C/E/F)] were developed in this study. A two-step manufacturing procedure was developed to achieve sufficient adhesiveness between the skin and core layers. The tensile, flatwise compressive, and longitudinal compressive properties of these sandwich composites were measured according to referred ASTM standards on a materials test system (MTS 810). Experimental results revealed that the WC core materials displayed excellent resistance to a flatwise compressive force and the foam core material show weak resistance. Under longitudinal compression, the skin and core layer of the C/E/F specimen separated, indicating that the C/E/F specimen could not withstand longitudinal force. Moreover, the C/E/WG and C/E/WC specimens both bend at the end of the same test.

A modified damping model of vector form intrinsic finite element method for high-speed spiral bevel gear dynamic characteristics analysis

2021 ◽  
pp. 030932472110188
Author(s):  
Xiangying Hou ◽  
Yuzhe Zhang ◽  
Hong Zhang ◽  
Jian Zhang ◽  
Zhengminqing Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Numerical Solutions ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Vector Form ◽  
Good Efficiency ◽  
Spiral Bevel ◽  
Damping Model

The vector form intrinsic finite element (VFIFE) method is springing up as a new numerical method in strong non-linear structural analysis for its good convergence, but has been constricted in static or transient analysis. To overwhelm its disadvantages, a new damping model was proposed: the value of damping force is proportional to relative velocity instead of absolute velocity, which could avoid inaccuracy in high-speed dynamic analysis. The accuracy and efficiency of the proposed method proved under low speed; dynamic characteristics and vibration rules have been verified under high speed. Simulation results showed that the modified VFIFE method could obtain numerical solutions with good efficiency and accuracy. Based on this modified method, high-speed vibration rules of spiral bevel gear pair under different loads have been concluded. The proposed method also provides a new way to solve high-speed rotor system dynamic problems.

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