Some Results and Issues in the Non-Destructive Evaluation of Sandwich Composite Structures

2001 ◽  
Author(s):  
Emmanuel O. Ayorinde ◽  
Ronald F. Gibson ◽  
Feizhong Deng
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Sandwich Beam ◽  
Sandwich Composite ◽  
Glass Composite ◽  
Transverse Loading ◽  
Three Point Bending ◽  
Damage States ◽  
Vibration Modal ◽  
Non Destructive

Abstract This paper focuses on the use of basic NDE methods like ultrasonics, imaging and vibration testing to assess the integrity of some sandwich composites which have been subjected to transverse loading. Samples of a foam core, glass composite facing sandwich beam of varying thicknesses and end notch lengths were tested in three point bending and assessed by these NDE methods. The results show that core shear and indentation failures appear to be the prominent failure modes for these geometries and materials, and that changes in the damping and vibration modal frequencies of the beams can indicate damage states.

Three-Point Bending Shear Stress of Wooden Sandwich Composite

2016 ◽  
Vol 852 ◽  
pp. 1337-1341
Author(s):  
Xin Feng Wu ◽  
Jian Ying Xu ◽  
Jing Xin Hao ◽  
Rui Liao ◽  
Zhu Zhong
Keyword(s):  
Shear Stress ◽  
Shear Force ◽  
Sandwich Beam ◽  
Single Layer ◽  
Skin Layer ◽  
Sandwich Composite ◽  
Three Point Bending ◽  
The Core ◽  
Sandwich Construction ◽  
Core Thickness

The effect of construction parameters and material type on bending shear stress and shear force was analyzed systematically. It is shown that maximum bending shear stress of sandwich construction is smaller than homogeneous single layer beam with same cross section if the skin has higher modulus than the core. Besides the effect of core or skin layer to shear force is almost identical for sandwich composite composed by different materials with same construction parameter. In addition, the shear force can be taken almost by the core of sandwich beam only if the ratio of core thickness to the whole is more than. Otherwise the resistance to shear force of skin layer should be considered to calculate the shear deformation. The results can provide basic theory for design optimization of sandwich construction.

scholarly journals Non Destructive Investigation of Defects in Composite Structures by Full-Field Measurement Methods

2013 ◽  
Vol 550 ◽  
pp. 135-142
Author(s):  
Elodie Péronnet ◽  
Marie Laetitia Pastor ◽  
Richard Huillery ◽  
Olivier Dalverny ◽  
Sébastien Mistou ◽  
...  
Keyword(s):  
Defect Detection ◽  
Field Measurement ◽  
Composite Structures ◽  
Measurement Methods ◽  
Sandwich Composite ◽  
Full Field ◽  
X Ray ◽  
Full Field Measurement ◽  
Application Fields ◽  
Non Destructive

This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed.

scholarly journals Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

2021 ◽  
Author(s):  
Luca Boccarusso ◽  
Fulvio Pinto ◽  
Stefano Cuomo ◽  
Dario De Fazio ◽  
Kostas Myronidis ◽  
...  
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Industrial Applications ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Continuous Manufacturing ◽  
Low Velocity ◽  
Impact Compression

AbstractAdvanced sandwich composite structures that incorporate foams or honeycombs as core materials, have been extensively investigated and used in various applications. One of the major limitations of the conventional materials used is their weak impact resistance and their end-of-life recyclability and overall sustainability. This paper is focused on the study of the production and mechanical characterization of hybrid sandwich panels using hemp bi-grid cores that were manufactured with an ad hoc continuous manufacturing process. Bi-grid structures were stratified in multiple layers, resulting in cores with different thicknesses and planar density. Sandwich panels made with carbon fibers skins were then subjected to Low Velocity Impact, compression and indentation and the damaged panels were investigated via CT-Scan. Results show that the high tailorability of the failure modes and the very good energy absorption properties of the hybrid material open new exciting perspectives for the development of new sandwich structures that can extend the use of natural fibers into several industrial applications.

Bending Response of Composite Sandwich Beams with M-Type Folded Cores

2014 ◽  
Vol 1049-1050 ◽  
pp. 452-455
Author(s):  
Li Xin Cong ◽  
Yu Guo Sun
Keyword(s):  
Failure Modes ◽  
Fiber Composite ◽  
Sandwich Beam ◽  
Deformation Mode ◽  
Sandwich Beams ◽  
The Finite Element Method ◽  
Carbon Fiber Composite ◽  
Maximum Displacement ◽  
Three Point Bending ◽  
Composite Sandwich

Bending properties and failure modes of sandwich structure with carbon fiber composite M-type folded cores were investigated and presented in this paper. Three point bending responses of both sandwich beams were measured. The finite element method was utilized to determine deformation mode of sandwich beam with M-type folded cores. Cores buckling and debonding have been studied under three point bending and the maximum displacement was also studied using FE-analytical and experimental methods.

Human reliability in non-destructive inspections of nuclear power plant components: modeling and analysis

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
Vanderley Vasconcelos ◽  
Wellington Antonio Soares ◽  
Raissa Oliveira Marques ◽  
Silvério Ferreira Silva Jr ◽  
Amanda Laureano Raso
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Human Factors ◽  
Nuclear Power ◽  
Power Plants ◽  
Failure Modes ◽  
Cooling System ◽  
Human Reliability ◽  
Non Destructive ◽  
Plant Components

Non-destructive inspection (NDI) is one of the key elements in ensuring quality of engineering systems and their safe use. This inspection is a very complex task, during which the inspectors have to rely on their sensory, perceptual, cognitive, and motor skills. It requires high vigilance once it is often carried out on large components, over a long period of time, and in hostile environments and restriction of workplace. A successful NDI requires careful planning, choice of appropriate NDI methods and inspection procedures, as well as qualified and trained inspection personnel. A failure of NDI to detect critical defects in safety-related components of nuclear power plants, for instance, may lead to catastrophic consequences for workers, public and environment. Therefore, ensuring that NDI is reliable and capable of detecting all critical defects is of utmost importance. Despite increased use of automation in NDI, human inspectors, and thus human factors, still play an important role in NDI reliability. Human reliability is the probability of humans conducting specific tasks with satisfactory performance. Many techniques are suitable for modeling and analyzing human reliability in NDI of nuclear power plant components, such as FMEA (Failure Modes and Effects Analysis) and THERP (Technique for Human Error Rate Prediction). An example by using qualitative and quantitative assessesments with these two techniques to improve typical NDI of pipe segments of a core cooling system of a nuclear power plant, through acting on human factors issues, is presented.

Non-Destructive Testing of Thermoplastic Carbon Composite Structures

2020 ◽  
Vol 2020 (1) ◽  
pp. 34-52
Author(s):  
Rafał Szymański
Keyword(s):  
Composite Structures ◽  
Ultrasonic Method ◽  
Composite Panel ◽  
Aviation Industry ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Pulse Technique ◽  
Thermoplastic Matrix ◽  
The Subject ◽  
Non Destructive

AbstractThe article is in line with the contemporary interests of companies from the aviation industry. It describes thermoplastic material and inspection techniques used in leading aviation companies. The subject matter of non-destructive testing currently used in aircraft inspections of composite structures is approximated and each of the methods used is briefly described. The characteristics of carbon preimpregnates in thermoplastic matrix are also presented, as well as types of thermoplastic materials and examples of their application in surface ship construction. The advantages, disadvantages and limitations for these materials are listed. The focus was put on the explanation of the ultrasonic method, which is the most commonly used method during the inspection of composite structures at the production and exploitation stage. Describing the ultrasonic method, the focus was put on echo pulse technique and the use of modern Phased Array heads. Incompatibilities most frequently occurring and detected in composite materials with thermosetting and thermoplastic matrix were listed and described. A thermoplastic flat composite panel made of carbon pre-impregnate in a high-temperature matrix (over 300°C), which was the subject of the study, was described. The results of non-destructive testing (ultrasonic method) of thermoplastic panel were presented and conclusions were drawn.

Failure Analysis Case Study of a 1.5 Meter Space Flex Harness

2017 ◽  
Author(s):  
Erick Kim ◽  
Kamjou Mansour ◽  
Gil Garteiz ◽  
Javeck Verdugo ◽  
Ryan Ross ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Failure Modes ◽  
Field Of View ◽  
Area Of Interest ◽  
Air Stream ◽  
Novel Method ◽  
Temperature Controlled ◽  
Non Destructive ◽  
Failure Site

Abstract This paper presents the failure analysis on a 1.5m flex harness for a space flight instrument that exhibited two failure modes: global isolation resistances between all adjacent traces measured tens of milliohm and lower resistance on the order of 1 kiloohm was observed on several pins. It shows a novel method using a temperature controlled air stream while monitoring isolation resistance to identify a general area of interest of a low isolation resistance failure. The paper explains how isolation resistance measurements were taken and details the steps taken in both destructive and non-destructive analyses. In theory, infrared hotspot could have been completed along the length of the flex harness to locate the failure site. However, with a field of view of approximately 5 x 5 cm, this technique would have been time prohibitive.

Failure Analysis Strategies for Multistacked Memory Devices with TSV Interconnects

2015 ◽  
Author(s):  
Frank Altmann ◽  
Christian Grosse ◽  
Falk Naumann ◽  
Jens Beyersdorfer ◽  
Tony Veches
Keyword(s):  
Failure Analysis ◽  
Focused Ion Beam ◽  
Failure Modes ◽  
Ion Beam ◽  
Memory Devices ◽  
Metallographic Cross Section ◽  
Electron Beam Induced Current ◽  
Thermal Simulations ◽  
Lock In ◽  
Non Destructive

Abstract In this paper we will demonstrate new approaches for failure analysis of memory devices with multiple stacked dies and TSV interconnects. Therefore, TSV specific failure modes are studied on daisy chain test samples. Two analysis flows for defect localization implementing Electron Beam Induced Current (EBAC) imaging and Lock-in-Thermography (LIT) as well as adapted Focused Ion Beam (FIB) preparation and defect characterization by electron microscopy will be discussed. The most challenging failure mode is an electrical short at the TSV sidewall isolation with sub-micrometer dimensions. It is shown that the leakage path to a certain TSV within the stack can firstly be located by applying LIT to a metallographic cross section and secondly pinpointing by FIB/SEM cross-sectioning. In order to evaluate the potential of non-destructive determination of the lateral defect position, as well as the defect depth from only one LIT measurement, 2D thermal simulations of TSV stacks with artificial leakages are performed calculating the phase shift values per die level.

scholarly journals Evaluation of the influence of design in the mechanical properties of honeycomb cores used in composite panels

2021 ◽  
pp. 146442072098519
Author(s):  
A Miranda ◽  
M Leite ◽  
L Reis ◽  
E Copin ◽  
MF Vaz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Failure Modes ◽  
Industrial Applications ◽  
Sandwich Composite ◽  
Composite Panels ◽  
Distribution Analysis ◽  
Absorbed Energy ◽  
Fused Filament Fabrication ◽  
Subtractive Manufacturing

The aerospace, automotive, and marine industries are heavily reliant on sandwich panels with cellular material cores. Although honeycombs with hexagonal cells are the most commonly used geometries as cores, recently there have been new alternatives in the design of lightweight structures. The present work aims to evaluate the mechanical properties of metallic and polymeric honeycomb structures, with configurations recently proposed and different in-plane orientations, produced by additive and subtractive manufacturing processes. Structures with configurations such as regular hexagonal honeycomb (Hr), lotus (Lt), and hexagonal honeycomb with Plateau borders (Pt), with 0°, 45°, and 90° orientations were analyzed. To evaluate its properties, three-point bending tests were performed, both experimentally and by numerical modeling, by means of the finite element method. Honeycombs of two aluminum alloys and polylactic acid were fabricated. The structures produced in aluminum were obtained either by selective laser melting technology or by machining, while polylactic acid structures were obtained by material extrusion using fused filament fabrication. From the stress distribution analysis and the load–displacement curves, it was possible to evaluate the strength, stiffness, and absorbed energy of the structures. Failure modes were also analyzed for polylactic acid honeycombs. In general, a strong correlation was observed between numerical and experimental results. The results show that the stiffness and absorbed energy increase in the order, Hr, Pt, Lt, and with the orientation through the sequence, 45°, 90°, 0°. Thus, Lt structures with 0° orientation seem to be good alternatives to the traditional honeycombs used in sandwich composite panels for those industrial applications where low weight, high stiffness, and large energy-absorbing capacity are required.

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