Vibration and wave number characterization in carbon-fiber sandwich composite structures

2012 ◽  
Author(s):  
J. Sargianis ◽  
J. Suhr
Keyword(s):  
Carbon Fiber ◽  
Composite Structures ◽  
Wave Number ◽  
Sandwich Composite

Fabrication, characterization and mechanical testing of carbon fiber sandwich composites with nanoparticle included polyurethane adhesives

2021 ◽  
pp. 002199832110588
Author(s):  
Mehmet Emin Çetin
Keyword(s):  
Carbon Fiber ◽  
Composite Structures ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Synergistic Effects ◽  
Sandwich Panels ◽  
Sandwich Composite ◽  
Scanning Calorimetry ◽  
Aluminum Honeycomb ◽  
Out Of Autoclave

In honeycomb core and composite face sheet sandwich panels, it is essential to understand the bonding characteristics of adhesive in relevance with its properties to observe synergistic effects of reinforcing nanoparticles such as multi-walled carbon nanotubes (MWCNTs). This study investigates the effects of MWCNT inclusion on polyurethane (PU) adhesive, which directly affects sandwich structures' structural and mechanical performance. MWCNTs are added to PU adhesive up to 0.2%, and their RAMAN spectroscopic analysis, Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analyses (TGA) and differential-scanning calorimetry analyses (DSC) are evaluated. Aluminum honeycomb carbon-fiber-reinforced composite (CFRC) sandwich panels are fabricated using an out-of-autoclave manufacturing process. Carbon-fiber prepreg is used for top/bottom face sheets. Mechanical strength of face/core bonding evaluated as a function of MWCNT addition and core cell sizes. Manufactured sandwich composite structures are investigated for flat-wise tensile strength and three-point bending strength. Results show that MWCNT reinforcement to PU adhesive and lower cell size increases bending and flat-wise tensile resistances.

Wave propagation in composite structures

2009 ◽  
Vol 225 (3) ◽  
pp. 639-648
Author(s):  
O Bareille ◽  
M N Ichchou
Keyword(s):  
Numerical Method ◽  
Composite Structures ◽  
Wave Number ◽  
Sandwich Composite ◽  
Flexural Wave ◽  
Honeycomb Core ◽  
Matching Criterion ◽  
Wave Numbers ◽  
Identification Technique ◽  
Measured Displacement

Dynamic behaviour of honeycomb-core composite structures forms the framework of this article. The wave numbers of propagative waves are the elements of comparison between a numerical method (wave finite-element method) and an experimental identification technique (inhomogeneous wave correlation). The numerical method is based on the description of the dynamics of periodic waveguides. The experimental technique uses a matching criterion with the measured displacement field to obtain the corresponding wave numbers for a wave-based description of the displacement. Both approaches are applied to a sandwich composite beam with a honeycomb core. They seem to be in quite good accordance with analytical results for the flexural wave number.

ONR REVIEW: ARCHITECTED COMPOSITES FOR DAMAGE TOLERANCE IN EXTREME CONDITIONS

2021 ◽  
Author(s):  
PAVANA PRABHAKAR ◽  
VINAY DAMODARAN, ◽  
ABARINATHAN PUSHPARAJ SUBRAMANIYAN
Keyword(s):  
Energy Dissipation ◽  
Composite Structures ◽  
Computational Models ◽  
Peak Load ◽  
Moisture Diffusion ◽  
Honeycomb Structure ◽  
Sandwich Composite ◽  
Extreme Conditions ◽  
Improved Performance ◽  
Damage Tolerant

The long-term goal of this ONR funded project is to facilitate the design of architected composites that play a key role in damage tolerant and resilient structures. The main emphasis is on developing new composite structures with improved performance and durability as compared to conventional structural composites. To that end, we will present our work in detail on the following within the realm of sandwich composites along with a novel Machine Learning framework for stress prediction in composites: 1) Novel recoverable sandwich composite structures: Traditional sandwich cores such as foam core or honeycomb structures are good options for enabling lightweight and stiff structures. Although, these cores are known to dissipate energy under extreme conditions such as impact loading, they experience permanent damage. Here, our goal is to design core structures that undergo substantial deformation without accumulating damage and recover their original geometric configuration after the loading is removed. In contrast to a traditional foam or honeycomb structure, we have developed a multi-layer architected core design that facilitates significant deformation beyond the initial peak load, yielding a larger energy dissipation during impact and other extreme loading scenarios. We utilize the concept of pseudo-bistability of truncated cone unit cells to achieve elastic buckling for energy dissipation and shape recovery of core structures. 2) Tailoring of sandwich composite facings: Our objective is to establish the influence of fiber architecture on moisture diffusion pathways in FRPC facings for enabling damage tolerant facing designs. To that end, we have evaluated the moisture kinetics in FRPCs by developing micromechanics based computational models within FEM. We have explained the effect of tortuous diffusion pathways that manifest within FRPCs due to internal fiber architectures. Finally, we established the relationship between tortuosity and diffusivity that can be used for studying moisture diffusion in other FRPCs.

Edge Illumination X-Ray Phase Contrast Imaging and Ultrasonic Attenuation for Porosity Quantification in Composite Structures

2021 ◽  
Author(s):  
Dana Shoukroun ◽  
Sandro Olivo ◽  
Paul Fromme
Keyword(s):  
Carbon Fiber ◽  
Composite Structures ◽  
Phase Contrast ◽  
Ultrasonic Attenuation ◽  
Aerospace Industry ◽  
Composite Plates ◽  
Phase Contrast Imaging ◽  
Fiber Reinforced ◽  
Contrast Imaging ◽  
X Ray

Abstract Carbon fiber reinforced composites are widely used in the aerospace industry, due to their low weight and high strength. Porosity often occurs during the manufacturing of composite structures, which can compromise the structural integrity of the part and affect its mechanical properties. In the aerospace industry a typical requirement for structural components is for the porosity content to be kept below 2%. Non-destructive evaluation (NDE) techniques are used to estimate the porosity content in composite components, the most common being ultrasonic attenuation and X-ray computed tomography (CT). Planar Edge Illumination X-ray Phase Contrast Imaging (EI XPCI) was used to quantify the porosity content in woven carbon fiber reinforced composite plates with porosity ranging between 0.7% and 10.7%. A new metric was introduced, the standard deviation of the differential phase (STDVDP) signal, which represents the variation of inhomogeneity in the plates for features of a scale equal to or above the system resolution (here 12μm). The SDTVDP was found to have a very high correlation with porosity content estimated from matrix digestion and ultrasonic attenuation, hence providing a promising new methodology to quantify porosity in composite plates.

Multi-Objective Optimal Design of Sandwich Composite Laminates Using Simulated Annealing and FEM

2008 ◽  
Author(s):  
A. Sarhadi ◽  
M. Tahani ◽  
F. Kolahan ◽  
M. Sarhadi
Keyword(s):  
Simulated Annealing ◽  
Optimal Design ◽  
Composite Laminates ◽  
Composite Structures ◽  
Simulated Annealing Algorithm ◽  
Core Layer ◽  
Sandwich Composite ◽  
Surface Layers ◽  
Multi Objective ◽  
Aspect Ratios

Multi-objective optimal design of sandwich composite laminates consisting of high stiffness and expensive surface layers and low-stiffness and inexpensive core layer is addressed in this paper. The object is to determine ply angles and number of surface layers and core thickness in such way that natural frequency is maximized with minimal material cost and weight. A simulated annealing algorithm with finite element method is used for simultaneous cost and weight minimization and frequency maximization. The proposed procedure is applied to Graphite-Epoxy/Glass-Epoxy and Graphite-epoxy/Aluminum sandwich laminates and results are obtained for various boundary conditions and aspect ratios. Results show that this technique is useful in designing of effective, competitive and light composite structures.

Buckling Analysis of Carbon Fiber Reinforced Plastics Cylinders under Axial Compression

2013 ◽  
Vol 395-396 ◽  
pp. 76-79
Author(s):  
Da Huang ◽  
Cheng Hong Duan
Keyword(s):  
Carbon Fiber ◽  
Axial Compression ◽  
Composite Structures ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced ◽  
The Stability

In this paper, the stability of carbon fiber reinforced plastics (CFRP) cylinders under axial compression was studied by the finite element analysis method. According to the Riks method, compressive capacity of the composite structures was investigated by nonlinear analysis, in which the eigen buckling modes were considered in the form of initial defects. And the post-buckling performances of different structures were also compared.

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