scholarly journals Structural integrity of engineering composite materials: a cracking good yarn

2016 ◽  
Vol 374 (2071) ◽  
pp. 20160057 ◽  
Author(s):  
Peter W. R. Beaumont ◽  
Costas Soutis
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Large Scale ◽  
Structural Integrity ◽  
High Efficiency ◽  
Human Life ◽  
Engineering Structures ◽  
Catastrophic Fracture ◽  
Materials Used ◽  
Integrity Analysis

Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a ‘fracture safe design’ is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

Targeting Problems of Composite Failure

2009 ◽  
Vol 417-418 ◽  
pp. 37-40 ◽  
Author(s):  
Peter W.R. Beaumont
Keyword(s):  
Life Expectancy ◽  
Stress Corrosion Cracking ◽  
Large Scale ◽  
Structural Integrity ◽  
Engineering Structures ◽  
Composite Failure ◽  
Long Life ◽  
Catastrophic Fracture ◽  
Materials Used ◽  
Integrity Analysis

Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Fitness considerations for long-life implementation of aerospace composites include understanding phenomena such as fatigue, creep and stress corrosion cracking that affect reliability, life expectancy, and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined; furthermore, SI takes into account service duty.

Composite Fracture: Getting to the Heart of the Matter

2011 ◽  
Vol 471-472 ◽  
pp. 1-6
Author(s):  
Peter W.R. Beaumont
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Structural Integrity ◽  
Constitutive Models ◽  
Process Variables ◽  
Material Systems ◽  
New Knowledge ◽  
Structural Composite ◽  
Successful Design ◽  
Materials Used

The demands made on structural composite materials in modern design are increasingly stringent. Greater performance, lower costs, increased reliability and safety all require that the design engineer knows more and more of the material systems available. Bringing together new knowledge contained in constitutive models of continuum design and empirical information from a girth of experience is proving to be difficult because the number of service and process variables required for sophisticated, optimal design is becoming increasingly larger. Understanding Structural Integrity (SI) provides the key to the successful design, certification, and safety of large composite structures and engineering composite materials. This is because SI analysis treats simultaneously the design, the materials used, figures out how best components and parts are joined, and takes service duty into account. But predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic failure of the structure will occur remains an unsolved mystery.

Damage in Composite Material: A Microwave Detection

2014 ◽  
Vol 605 ◽  
pp. 303-305
Author(s):  
Jerome Rossignol ◽  
Alain Thionnet
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Dielectric Material ◽  
Low Cost ◽  
Unidirectional Composite ◽  
Microstrip Resonator ◽  
Microwave Frequencies ◽  
Fibre Break ◽  
Materials Used ◽  
Non Destructive

In the field of the transport, the increase of the security rule recommends to a periodic control of the structure to detect damage due to mechanical loadings. Now, current materials, used in the case of transport applications, are the composite materials. The methods, to control these materials or composite structures, need to be low cost, non-destructive, in-situ and swiftness as far as possible. The scientific literature reports many methods to control the damage in composite materials and structures. However the above requirements and the adaptation to composite materials reduce the number of methods that can be used. Currently, the adapted methods are based on infrared thermography, acoustical emission, EMIR (ElectroMagnetic InfraRed) or microwave imagery. We present an innovative non-destructive method of detecting damages in composite materials. The method is based on the observation and analysis of the modification in dielectric material resulting from damage. The originality of this method is that the diagnostic is obtained by using a microstrip resonator at microwave frequencies. The feasibility of the method is demonstrated by the detection of a fibre break into an unidirectional composite submitted to a flexural loading. The fibre break is the damage to detect. The perspective of this work is to develop a quantification and a localization of damages.

A Review of Damage Tolerant Design, Certification and Repair in Metals Compared to Composite Materials

2014 ◽  
Vol 891-892 ◽  
pp. 1597-1602 ◽  
Author(s):  
Nabil Chowdhury ◽  
Wing Kong Chiu ◽  
John Wang
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Failure Modes ◽  
Structural Integrity ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Repair Efficiency ◽  
Mechanically Fastened ◽  
Damage Tolerant

A review of some of the various fatigue models introduced over the years for both metallic materials, in particular aluminium alloys followed by fatigue and durability concerns associated with composite materials. The move towards light weight and high stiffness structures that have good fatigue durability and corrosion resistance has led to the rapid move from metal structures to composite structures. With this brings the added concern of certifying new components as the damage mechanisms and failure modes in metals differ significantly than composite materials such as carbon fiber reinforced polymers (CFRP). The certification philosophy for composites must meet the same structural integrity, safety and durability requirements as that of metals. Hence this is where the challenge now lies. Substantial work has been conducted in the reparability of composite structures through bonding using various adherend thicknesses and joint types and has been shown to have higher durability than mechanically fastened repairs for thin adherends however these are currently unacceptable repair methods as they cannot be certified. Repairs are designed on the basis that the repair efficiency can be predicted and should be designed conservatively with respect to the various failure modes and include the surrounding structure.

Rapid Assessment of Natural Periods of Large Short-Period Civil Engineering Structures

2013 ◽  
Vol 569-570 ◽  
pp. 286-293
Author(s):  
Vikram Pakrashi ◽  
Biswajit Basu ◽  
Kevin Ryan
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Rapid Assessment ◽  
Ambient Vibration ◽  
Empirical Formulas ◽  
Long Distance ◽  
Engineering Structures ◽  
Historical Structures ◽  
Model Free ◽  
Short Period

Rapid assessment of large, short-period structures is extremely important for establishing structural integrity. This paper demonstrates experimental non-contact detection of consistent frequency peaks from the ambient vibration of a range of large buildings. Long distance, remote Laser Doppler Vibrometry is employed to estimate the dominant response frequencies of these large building structures from their ambient vibration. These dominant frequencies were reproducible in the frequency domain. The results demonstrate potential field applications of this method in a number of important applications. Such applications include model-free and rapid assessment or monitoring of historical structures, strategically important structures, lifelines, assessment and monitoring of structures such as nuclear facilities and rapid evaluation of large scale structures following disasters. Empirical formulas specified in codes do not cover such special structures and experimental determination of periods employing the method proposed may thus become essential.

Validation of Constraint Based Methodology in Structural Integrity: VOCALIST — Analytical Programme

2003 ◽  
Author(s):  
Elisabeth Keim ◽  
Michael Ludwig ◽  
Richard Bass ◽  
Wallace McAfee ◽  
Sean Yin ◽  
...  
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Structural Features ◽  
Experimental Program ◽  
Safety Margins ◽  
Standard Specimens ◽  
First Results ◽  
Materials Used ◽  
Constraint Effects ◽  
Large Scale Tests

The aim of the European Community (EC) project VOCALIST (Validation of Constraint-Based Assessment Methodology in Structural Integrity) is to develop and validate innovative procedures for assessing the level of, and possible changes to, constraint-based safety margins in ageing nuclear pressure boundary components. An iterative process of experiment and analysis will address this overall objective. The analytical investigations within VOCALIST cover all three ferritic materials used in the experimental program. Two of the three materials are investigated in the ductile to brittle transition regime and the third material will be tested in the ductile regime. The main effort is to predict the results of the large-scale tests in terms of constraint effects. All participants use constraint based methods, which as a first step are calibrated to the behaviour of standard specimens and then applied to the structural features and (or) large scale tests of each material. In this contribution the progress since last year of the analytical program of VOCALIST will be reported. The analyses of the specimens and components under investigation are highlighted with respect to modelling aspects and the first results are presented.

scholarly journals Transparent Polyurethane Nanofiber Air Filter for High-Efficiency PM2.5 Capture

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Wen Liang ◽  
Yuan Xu ◽  
Xiao Li ◽  
Xiao-Xiong Wang ◽  
Hong-Di Zhang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Large Scale ◽  
High Efficiency ◽  
Residential Buildings ◽  
Human Life ◽  
Thermoplastic Polyurethane ◽  
Fine Particulate Matter ◽  
Ventilation Rate ◽  
Air Filter ◽  
High Productivity

AbstractFine particulate matter (PM) has seriously affected human life, such as affecting human health, climate, and ecological environment. Recently, many researchers use electrospinning to prepare nanofiber air filters for effective removal of fine particle matter. However, electrospinning of the polymer fibers onto the window screen uniformly is only achieved in the laboratory, and the realization of industrialization is still very challenging. Here, we report an electrospinning method using a rotating bead spinneret for large-scale electrospinning of thermoplastic polyurethane (TPU) onto conductive mesh with high productivity of 1000 m2/day. By changing the concentration of TPU in the polymer solution, PM2.5 removal efficiency of nanofiber-based air filter can be up to 99.654% with good optical transparency of 60%, and the contact angle and the ventilation rate of the nanofiber-based air filter is 128.5° and 3480 mm/s, respectively. After 10 times of filtration, the removal efficiency is only reduced by 1.6%. This transparent air filter based on TPU nanofibers has excellent filtration efficiency and ventilation rate, which can effectively ensure indoor air quality of the residential buildings.

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