scholarly journals Enhancing the Out-of-Plane Compressive Performance of Lightweight Polymer Foam Core Sandwiches

Author(s):  
Çağrı UZAY
2005 ◽  
Author(s):  
M. C. Rice ◽  
C. A. Fleischer ◽  
D. D. R. Cartie ◽  
Marc Zupan

Improving lightweight structures is a continuous challenge for yacht hull structural components. Sandwich beams consisting of strong face sheets and a low density core have gained application as weight efficient structures subjected to bending loads. The sandwich structure provides good stiffness by keeping the face sheets at a fixed distance with considerable weight reduction over a statically equivalent monolithic panel. New fabrication technologies now allow for hybrid sandwich structures, known as X-cor to be manufactured. X-cor panels consist of carbon fiber face sheets separated by a closed cell polymer foam core reinforced with carbon fiber or metallic (Titanium or Steel) pins. The pins are inserted into the light weight foam core in the out-of-plane direction and extend from face sheet to face sheet. Pin orientation and concentration can be varied providing a large design space for scientist and designer to explore and to improve material performance. The effect of core thickness, pin reinforcing and polymer foam core on the out-of-plane axial compression response of these panel will be presented. The through thickness three- point simply supported bending behavior of these reinforced panels is used to evaluate the core shear, stretch, face sheet failure characteristics of the structures. Explicit experimental observations are used to develop and calibrate analytical energy balance models to generate failure mode maps describing the panel collapse load as a function of geometry. Multi-scale effective modeling, blurring the distinction between structural and material behavior, will enable optimization of the X-cor sandwich structures in light of Yacht hull design requirements. The mechanical response of X-cor sandwich panels will be compared to current Yacht hull materials using material selection charts, and demonstrator components presented.


2018 ◽  
Vol 134 (1) ◽  
pp. 231-234
Author(s):  
Y. Can ◽  
M. Yazıcı ◽  
H. Güçlü

Author(s):  
Anaïs Farrugia ◽  
Charles Winkelmann ◽  
Valeria La Saponara ◽  
Jeong Sik Kim ◽  
Anastasia H. Muliana

In service, composite structures present the unique challenge of damage detection and repair. Piezoelectric ceramic, such as lead zirconate titanate (PZT), is often used for detecting damage in composites. This paper investigates the effect of embedded PZT crystals on the overall creep behavior of sandwich beams comprising of glass fiber reinforced polymer laminated skins and polymer foam core, which could potentially be used as a damage-detecting smart structure. Uniaxial quasi-static and creep tests were performed on the glass/epoxy laminated composites having several fiber orientations, 0 deg, 45 deg, and 90 deg, to calibrate the elastic and viscoelastic properties of the fibers and matrix. Three-point bending creep tests at elevated temperature (80°C) were then carried out for a number of control sandwich beams (no PZT crystal) and conditioned sandwich beams (with PZT crystals embedded in the center of one facesheet). Lateral deflection of the sandwich beams was monitored for more than 60 h. The model presented in this paper is composed by two parts: (a) a simplified micromechanical model of unidirectional fiber reinforced composites used to obtain effective properties and overall creep response of the laminated skins and (b) a finite element method to simulate the overall creep behavior of the sandwich beams with embedded PZT crystals. The simplified micromechanical model is implemented in the material integration points within the laminated skin elements. Fibers are modeled as linear elastic, while a linearized viscoelastic material model is used for the epoxy matrix and foam core. Numerical results on the creep deflection of the smart sandwich beams show good correlations with the experimental creep deflection at 80°C, thus proving that this model, although currently based on material properties reported at room temperature, is promising to obtain a reasonable prediction for the creep of a smart sandwich structure at high temperatures.


Author(s):  
Xiaolong Tong ◽  
Michelle S. Hoo Fatt ◽  
Anudeep Reddy Vedire

2019 ◽  
Vol 135 (4) ◽  
pp. 769-771
Author(s):  
Y. Can ◽  
H. Güçlü ◽  
İ. K. Türkoğlu ◽  
İ. Kasar ◽  
M. Yazıcı

2017 ◽  
Vol 742 ◽  
pp. 673-680
Author(s):  
M. Adli Dimassi ◽  
Axel S. Herrmann

The use of sandwich structures is well established in industrial sectors where high stiffness and strength combined with lightweight are required, like in marine, wind turbine and railway applications. However, the vulnerability of sandwich structures to low-velocity impacts limits its use in primary aircraft structures. Pin reinforcement of the foam core enhances the out-of-plane properties and the damage tolerance of the foam core. In this paper, a finite element model is proposed to predict the impact behaviour of pin-reinforced sandwich structure. An approach based on the building block approach was used to develop the model. Multi-scale modelling in the impact region that considers the delamination of the face sheet using cohesive zone elements was employed to increase the accuracy of the simulation. Impact tests were performed to validate the numerical model. A good agreement between numerical and experimental results in terms of contact-force displacement history and failure mode was found.


2017 ◽  
Vol 22 (1) ◽  
pp. 40-54 ◽  
Author(s):  
Nilanjan Mitra ◽  
Alak K. Patra ◽  
Satya P Singh ◽  
Shyamal Mondal ◽  
Prasanta K Datta ◽  
...  

Identification of interfacial delamination in the glass fiber/polymer-foam-core sandwich composites is difficult if the delamination does not propagate to the side surface of the specimen. However, these damages may eventually lead to compromising the sandwich composite structural component. A cost-effective novel embedded fiber optic sensor is being proposed in this manuscript, which works on the principle of multimode interference, to perform distributed sensing of interfacial delamination within the sandwich composites while in service. Even though this easy to use methodology has been used to identify interfacial delamination, this methodology can also be used for different other types of interfacial/interlaminar distributed strain sensing of samples under mechanical as well as thermal loads.


Author(s):  
A Alavi Nia ◽  
M Kazemi

The aim of this study was to evaluate the penetration of ballistic projectiles into the sandwich panels both analytically and numerically. Due to the complexity of the mathematical equations governing this phenomenon, very few analytical studies have been conducted in this area. Given the widespread use of sandwich panels consisting of metal face-sheets and metal foam core in aerospace industries, revisions are carried out on analytical method provided by Hoo Fatt et al. on polymer foam core and composite face-sheets sandwich panels. Then using the improved relations, the high speed impact of a cylindrical projectile on the sandwich panels with aluminum face-sheets and aluminum foam core with different density ratios has been discussed. Also, the penetration process is simulated and finally to evaluate the accuracy of the improved analytical method and simulations, the results are compared to the experimental data obtained from tests have been done on the panels with aluminum foam core and aluminum face-sheets. Results of the research show that the improved procedure and numerical simulations are in good agreement with the experiments.


2013 ◽  
Vol 845 ◽  
pp. 297-301 ◽  
Author(s):  
Behzad Abdi ◽  
Syed Azwan ◽  
Ayob Amran ◽  
Roslan Abdul Rahman ◽  
R.A. Abdullah

Free vibration modes of foam-core sandwich plates with and without polymer columns were experimentally identified from frequency response tests. The responses were made at selected locations on the plate surface by attaching a single-axis accelerometer to measure out-of-plane response. Resonant frequencies, relative damping ratios and mode shapes were established for the lowest 3 out-of-plane modes found in the frequency range of 0-900 Hz. The results show that the vibration characteristics were affected by the sandwich structure configuration and material properties.


Author(s):  
Nikhil P. Joshi ◽  
Anastasia H. Muliana

Sandwich composites with polymer foam core are currently used in load-bearing components in buildings and naval structures due to their high strength to weight and stiffness to weight ratios, excellent thermal insulation, and ease of manufacturing. During their service time, sandwich composites are exposed to various external mechanical and hygro-thermal stimuli. It is known that the constituent properties of the sandwich composites are greatly influenced by the temperature and moisture fields. Granville [1] conducted experiments to study the effect of moisture on structural, dimensional stability, weight gain and peel strength of sandwich composites. Morganti et al. [2] analyzed the effect of moisture on the dimensional stability of the sandwich composites and concluded that moisture affects the physical behavior of the composite directly by modifying its structural characteristics such as matrix degradation and microcracks between fiber and matrix etc. However, the effect of moisture on the deformations in the sandwich composite with the viscoelastic foam cores has not yet been studied. The time-dependent response of the sandwich composite (due to the viscoelastic foam core) is aggravated in the moist environment conditions. Thus, it becomes necessary to analyze the effect of moisture on the overall response of the sandwich composites.


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