scholarly journals Defect Detection in Aerospace Sandwich Composite Panels Using Conductive Thermography and Contact Sensors

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6689
Author(s):  
David I. Gillespie ◽  
Andrew W. Hamilton ◽  
Robert C. Atkinson ◽  
Xavier Bellekens ◽  
Craig Michie ◽  
...  
Keyword(s):  
Impact Damage ◽  
Primary Repair ◽  
Single Point ◽  
Weight Ratio ◽  
Sandwich Composite ◽  
Thermal Stimulus ◽  
Honeycomb Core ◽  
Commercial Aircraft ◽  
Common Structure ◽  
Carbon Fibre Reinforced Polymer

Sandwich panels consisting of two Carbon Fibre Reinforced Polymer (CFRP) outer skins and an aluminium honeycomb core are a common structure of surfaces on commercial aircraft due to the beneficial strength–weight ratio. Mechanical defects such as a crushed honeycomb core, dis-bonds and delaminations in the outer skins and in the core occur routinely under normal use and are repaired during aerospace Maintenance, Repair and Overhaul (MRO) processes. Current practices rely heavily on manual inspection where it is possible minor defects are not identified prior to primary repair and are only addressed after initial repairs intensify the defects due to thermal expansion during high temperature curing. This paper reports on the development and characterisation of a technique based on conductive thermography implemented using an array of single point temperature sensors mounted on one surface of the panel and the concomitant induced thermal profile generated by a thermal stimulus on the opposing surface to identify such defects. Defects are classified by analysing the differential conduction of thermal energy profiles across the surface of the panel. Results indicate that crushed core and impact damage are detectable using a stepped temperature profile of 80 ∘C The method is amenable to integration within the existing drying cycle stage and reduces the costs of executing the overall process in terms of time-to-repair and manual effort.

scholarly journals Mechanical behavior of sandwich structure composites for helicopters

2020 ◽  
Vol 12 (4) ◽  
pp. 155-162
Author(s):  
George PELIN ◽  
Cristina-Elisabeta PELIN ◽  
Adriana STEFAN ◽  
Alexandra PETRE ◽  
Alina DRAGOMIRESCU
Keyword(s):  
Mechanical Behavior ◽  
Composite Structure ◽  
Weight Ratio ◽  
High Strength ◽  
Mechanical Tests ◽  
Impact Behavior ◽  
Sandwich Composite ◽  
Maximum Efficiency ◽  
Commercial Aircraft ◽  
Sandwich Composite Structure

The visible part of the floors of a commercial aircraft has long been a standard issue for virtually every commercial aircraft, mainly due to the weight of the materials from which they were made. Floor parts must provide mechanical strength and dimensional stability, while keeping the weight of the aircraft as low as possible for maximum efficiency. The design of the 787 Dreamliner and the Airbus A380 aircraft brought new opportunities in the use of the sandwich composite structure, mainly due to their light weight and high strength-to-weight ratio. Thus, this paper investigates the mechanical behavior of sandwich composite panels composed of two sides of carbon fiber laminate and Nomex honeycomb core obtained in the autoclave and developed under the RoRCraft CompAct grant. The technical approaches of this work are mainly focused on the compression behavior and especially on the compression after impact behavior of the hybrid sandwich composite structure, for defining and obtaining an optimal structure for the floors. These mechanical tests are decisive for such materials and have been performed in accordance with international ASTM standards.

scholarly journals Sequential Laser–Mechanical Drilling of Thick Carbon Fibre Reinforced Polymer Composites (CFRP) for Industrial Applications

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2136
Author(s):  
Sharizal Ahmad Sobri ◽  
Robert Heinemann ◽  
David Whitehead
Keyword(s):  
Carbon Fibre ◽  
Polymer Composites ◽  
Weight Ratio ◽  
High Strength ◽  
Industrial Applications ◽  
Fibre Laser ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Thrust And Torque

Carbon fibre reinforced polymer composites (CFRPs) can be costly to manufacture, but they are typically used anywhere a high strength-to-weight ratio and a high steadiness (rigidity) are needed in many industrial applications, particularly in aerospace. Drilling composites with a laser tends to be a feasible method since one of the composite phases is often in the form of a polymer, and polymers in general have a very high absorption coefficient for infrared radiation. The feasibility of sequential laser–mechanical drilling for a thick CFRP is discussed in this article. A 1 kW fibre laser was chosen as a pre-drilling instrument (or initial stage), and mechanical drilling was the final step. The sequential drilling method dropped the overall thrust and torque by an average of 61%, which greatly increased the productivity and reduced the mechanical stress on the cutting tool while also increasing the lifespan of the bit. The sequential drilling (i.e., laser 8 mm and mechanical 8 mm) for both drill bits (i.e., 2- and 3-flute uncoated tungsten carbide) and the laser pre-drilling techniques has demonstrated the highest delamination factor (SFDSR) ratios. A new laser–mechanical sequence drilling technique is thus established, assessed, and tested when thick CFRP composites are drilled.

Prediction of Elastic Properties of Honeycomb Core Materials and Analysis of Interlaminar Stress of Honeycomb Sandwich Composite Plate

2006 ◽  
Vol 306-308 ◽  
pp. 763-768
Author(s):  
Hyoung Gu Kim ◽  
Hoong Soo Yoon ◽  
Nak Sam Choi
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Sandwich Composite ◽  
Plate Model ◽  
Honeycomb Core ◽  
Interlaminar Stresses ◽  
Honeycomb Sandwich ◽  
Honeycomb Sandwich Composite ◽  
Theoretical Results ◽  
Core Materials

Theoretical formulas for effective elastic modulus and Poisson's ratio of honeycomb core materials were proposed considering the bending, axial and shear deformations of cell walls. Theoretical results obtained by the formulas showed orthotropic elasticity and large Poisson’s ratio, which were comparable to results by finite element analysis(FEA). Tensile test of honeycomb sandwich composite(HSC) plates was performed for analysis of their deformation behaviors and interlaminar stresses. Equivalent plate model using the theoretical results of honeycomb core layer show that interlaminar shear stress occurring due to large difference of Poisson’s ratio between skin and honeycomb core layers led to the delamination in HSC plate under tensile loading. Load-displacement behavior of HSC specimen simulated by equivalent plate model coincided fairly with that of detailed FEA model similar to experimental results.

scholarly journals Innovation in Aircraft Cabin Interior Panels Part I: Technical Assessment on Replacing the Honeycomb with Structural Foams and Evaluation of Optimal Curing of Prepreg Fiberglass

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3207 ◽  
Author(s):  
Edgar Adrián Franco-Urquiza ◽  
Annika Dollinger ◽  
Mauricio Torres-Arellano ◽  
Saúl Piedra ◽  
Perla Itzel Alcántara Llanas ◽  
...  
Keyword(s):  
Weight Ratio ◽  
Viscoelastic Behavior ◽  
Compression Molding ◽  
Polyurethane Foams ◽  
Future Research ◽  
Honeycomb Core ◽  
Molding Process ◽  
Aircraft Cabin ◽  
Structural Applications ◽  
Cabin Interior

Sandwich composites are widely used in the manufacture of aircraft cabin interior panels for commercial aircraft, mainly due to the light weight of the composites and their high strength-to-weight ratio. Panels are used for floors, ceilings, kitchen walls, cabinets, seats, and cabin dividers. The honeycomb core of the panels is a very light structure that provides high rigidity, which is considerably increased with fiberglass face sheets. The panels are manufactured using the compression molding process, where the honeycomb core is crushed up to the desired thickness. The crushed core breaks fiberglass face sheets and causes other damage, so the panel must be reworked. Some damage is associated with excessive build-up of resin in localized areas, incomplete curing of the pre-impregnated fiberglass during the manufacturing process, and excessive temperature or residence time during the compression molding. This work evaluates the feasibility of using rigid polyurethane foams as a substitute for the honeycomb core. The thermal and viscoelastic behavior of the cured prepreg fiberglass under different manufacturing conditions is studied. The first part of this work presents the influence of the manufacturing parameters and the feasibility of using rigid foams in manufacturing flat panels oriented to non-structural applications. The conclusion of the article describes the focus of future research.

Impact Damage Research of Sandwich Composite Laminates

2013 ◽  
Vol 710 ◽  
pp. 136-141
Author(s):  
Li Jun Wei ◽  
Fang Lue Huang ◽  
Hong Peng Li
Keyword(s):  
Compressive Strength ◽  
Composite Laminates ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Compression Process ◽  
Velocity Impact ◽  
Residual Compressive Strength ◽  
Core Materials

Sandwich composite laminates structure is a classic application of composite material on actual aircraft structural. Dealing with low-velocity impact damage and residual compressive strength of sandwich composite laminates, explicit finite element method of ABAQUS/Explicit software was adopted to simulate low-velocity impact and compression process. Impact response and invalidation on compression between sandwich composite laminates with different core materials and regular composite laminates were compared. The simulation results indicated that softer core materials can absorb more impact energy, reduce the structure damage and enhance the residual compressive strength after impact.

Impact Damage Resistance and Tolerance of Honeycomb Core Sandwich Panels

2008 ◽  
Vol 42 (4) ◽  
pp. 385-412 ◽  
Author(s):  
K.S. Raju ◽  
B.L. Smith ◽  
J.S. Tomblin ◽  
K.H. Liew ◽  
J.C. Guarddon
Keyword(s):  
Impact Damage ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Damage Resistance

scholarly journals Impact Damage Resistance and Post-Impact Tolerance of Optimum Banana-Pseudo-Stem-Fiber-Reinforced Epoxy Sandwich Structures

2020 ◽  
Vol 10 (2) ◽  
pp. 684 ◽  
Author(s):  
Mohamad Zaki Hassan ◽  
S. M. Sapuan ◽  
Zainudin A. Rasid ◽  
Ariff Farhan Mohd Nor ◽  
Rozzeta Dolah ◽  
...  
Keyword(s):  
Composite Structures ◽  
Sandwich Structures ◽  
Impact Damage ◽  
Fiber Composite ◽  
Peak Load ◽  
Weight Ratio ◽  
Synthetic Fiber ◽  
Damage Area ◽  
Banana Fibers ◽  
The Impact

Banana fiber has a high potential for use in fiber composite structures due to its promise as a polymer reinforcement. However, it has poor bonding characteristics with the matrixes due to hydrophobic–hydrophilic incompatibility, inconsistency in blending weight ratio, and fiber length instability. In this study, the optimal conditions for a banana/epoxy composite as determined previously were used to fabricate a sandwich structure where carbon/Kevlar twill plies acted as the skins. The structure was evaluated based on two experimental tests: low-velocity impact and compression after impact (CAI) tests. Here, the synthetic fiber including Kevlar, carbon, and glass sandwich structures were also tested for comparison purposes. In general, the results showed a low peak load and larger damage area in the optimal banana/epoxy structures. The impact damage area, as characterized by the dye penetration, increased with increasing impact energy. The optimal banana composite and synthetic fiber systems were proven to offer a similar residual strength and normalized strength when higher impact energies were applied. Delamination and fracture behavior were dominant in the optimal banana structures subjected to CAI testing. Finally, optimization of the compounding parameters of the optimal banana fibers improved the impact and CAI properties of the structure, making them comparable to those of synthetic sandwich composites.

Sign in / Sign up

Export Citation Format

Share Document