scholarly journals Structural Integrity Assessment of Composites Plates with Embedded PZT Transducers for Structural Health Monitoring

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6148
Author(s):  
Tianyi Feng ◽  
M.H. Ferri Aliabadi
Keyword(s):  
Elastic Modulus ◽  
Lead Zirconate Titanate ◽  
Composite Structures ◽  
Structural Integrity ◽  
Fatigue Loading ◽  
Active Sensing ◽  
Case Scenario ◽  
Worst Case ◽  
Integrity Assessment ◽  
Compressive Tests

Active sensing using ultrasonic guided waves (UGW) is widely investigated for monitoring possible damages in composite structures. Recently, a novel diagnosed film based on a circuit-printed technique with piezoelectric lead zirconate titanate (PZT) transducers has been developed. The diagnostic film is a replacement for the traditional cable connection to PZT sensors and has been shown to significantly reduce the weight of the host structure. In this work, the diagnosed films were embedded into composite structures during manufacturing using a novel edge cut-out method during lay-up, which allowed for edge trimming after curing. In this paper, the effect of fatigue loading on the integrity of PZT transducers is initially investigated. The electro-mechanical impedance (EMI) properties at different fatigue loading cycles were used as the diagnostic measure for the performance of the sensors. At the same time, the behaviours of UGW were investigated at different fatigue loading cycles. It was found that the EMI properties and active sensing behaviours remained stable up to 1 million cycles for the force ranges of 0.5~5 kN and 1~10 kN. Next, the effect of embedding the diagnosed film on the mechanical properties of the host composite structure was investigated. Tensile and compressive tests were conducted and the elastic modulus of composite coupons with and without embedded PZT diagnosed films were compared. The elastic modulus of composite coupons with PZT diagnosed films embedded across the entire coupon reduced by as much as 20% for tensile tests and just over 10% for compressive tests compared to the coupons without embedded sensors. These reductions are considered the worst-case scenario, as in real structures the film would only be embedded in a relatively small area of the structure.

New Data on the Capacity of X-Joints Under Tension and Implications for Codes

2008 ◽  
Author(s):  
Adrian F. Dier ◽  
Philip Smedley ◽  
Gunnar Solland ◽  
Hege Bang
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Hot Spot ◽  
Case Scenario ◽  
Element Analysis ◽  
Worst Case ◽  
Numerical Work ◽  
Hot Spot Stress ◽  
Integrity Assessment ◽  
Existing Structures

This paper reviews available static strength data and presents results of finite element analyses on first crack loads and ultimate loads of X-joints in tension. A critique of existing guidance for such joints is given. An examination of hot spot stress for such joints is presented, together with new capacity formulations based on test data. The new formulations are verified with reference to new data from a finite element analysis. The new capacity formulations will be of interest to regulatory authorities, to designers of new offshore installations and to engineers carrying out assessments of existing structures. It is also expected that the formulations will be considered by code drafting committees, e.g. for API RP2A, ISO 19902 and NORSOK, during code revisions. The paper demonstrates that present guidance is unduly conservative in two respects: (1) high γ joints (i.e. thin-walled chords) in the range 0.7 ≤ β ≤ 0.9 joints (i.e. moderately high brace/chord diameter ratios), and (2) joints with β = 1.0 having low γ. However, it is shown that present guidance may be optimistic for low γ joints with β < 0.9. The new capacity formulations proposed in this paper correct these deficiencies. As one example, the new formulations give an increase of 60% in capacity compared to existing guidance for a joint with β = 1.0 and γ = 10, not untypical of many joints in service. In the near term, the paper may be most appreciated by those involved with structural integrity assessment studies. There have been some recent examples where existing guidance has indicated that some primary structural joints are under-strength. This has prompted extensive numerical work to prove the adequacy of the joints. A worst case scenario would be the implementation of unnecessary offshore strengthening work.

Superposition of Manoeuvres and Load Spectra Extrapolation

2006 ◽  
Vol 5-6 ◽  
pp. 255-262 ◽  
Author(s):  
Angela Cerrini ◽  
P. Johannesson ◽  
Stefano Beretta
Keyword(s):  
Structural Integrity ◽  
Working Life ◽  
Service Operations ◽  
Extreme Value Statistics ◽  
Case Scenario ◽  
Worst Case ◽  
Integrity Assessment ◽  
Load Spectra ◽  
Increasing Demand ◽  
Load Conditions

To face the increasing demand for long lasting, versatile and performing machines, a detailed analysis of the load conditions is required especially when structural integrity assessment has to be achieved. Usually acquisitions of load histories are shorter than the machine working life and an extrapolation of the signal for the total service life is needed. Traditional methods for load spectra extrapolation are based on conservative choices in terms of worst case scenario. Methods based on extreme value statistics have been developed. The problem addressed in this paper concerns the extrapolation of load histories on a welded boom in which different manoeuvres are superimposed. Different ways of extrapolating the load measurement have been derived, both in time domain and in Markov domain, in order to account for the superposition of bigger and more damaging cycles and smaller cycles caused by two different service operations.

Life-cycle health monitoring of composite structures using piezoelectric sensor network

2021 ◽  
Author(s):  
yinghong yu ◽  
Xiao Liu ◽  
jun li ◽  
Yishou Wang ◽  
xinlin qing
Keyword(s):  
Life Cycle ◽  
Sensor Network ◽  
Lead Zirconate Titanate ◽  
Health Monitoring ◽  
Composite Structures ◽  
Large Scale ◽  
Structural Integrity ◽  
Piezoelectric Sensor ◽  
Curing Process ◽  
Whole Life Cycle

Abstract The vacuum-assisted resin infusion (VARI) technique provides considerable advantages in manufacturing large-scale composite structures. An accurate and consecutive structural health monitoring system is urgently required to determine the initial quality and assess the structural integrity of a composite structure. In this paper, a real-time active smart diagnostic system (SDS) based on piezoelectric sensor network is proposed to monitor the whole life-cycle of composite structures. Experiments were conducted on carbon fiber reinforced plastic (CFRP) specimens with different thicknesses to investigate the monitoring capability of piezoelectric lead-zirconate-titanate (PZT) sensors used in the SDS approach. The PZT sensor networks inserted inside the composite structures during the VARI process are used to monitor not only the curing parameters, but also the health status of composite structures when they are in service after curing. To monitor the curing process only, the sensor network can also be installed on the bottom of the mould. Experimental results demonstrate that both three-dimensional resin flow and degree of cure (DOC) in the VARI process can be effectively monitored by the PZT sensor network. Meanwhile, the embedded PZT sensor network has the potential to identify the different stages in the curing process. It is obvious that the piezoelectric sensor network will provide important technical support for composite materials with the structure and function integrated.

scholarly journals Methodologies for the optimization of fibre-reinforced composite structures with manufacturing uncertainties

2006 ◽  
Author(s):  
◽  
Ryan Jason Hamilton
Keyword(s):  
Composite Structures ◽  
Design Space ◽  
Laminated Composite ◽  
Full Potential ◽  
Rectangular Plates ◽  
Case Scenario ◽  
Worst Case ◽  
Reinforced Plastics ◽  
Design Variables ◽  
Structural Applications

Fibre Reinforced Plastics (FRPs) have been used in many practical structural applications due to their excellent strength and weight characteristics as well as the ability for their properties to be tailored to the requirements of a given application. Thus, designing with FRPs can be extremely challenging, particularly when the number of design variables contained in the design space is large. For example, to determine the ply orientations and the material properties optimally is typically difficult without a considered approach. Optimization of composite structures with respect to the ply angles is necessary to realize the full potential of fibre-reinforced materials. Evaluating the fitness of each candidate in the design space, and selecting the most efficient can be very time consuming and costly. Structures composed of composite materials often contain components which may be modelled as rectangular plates or cylindrical shells, for example. Modelling of components such as plates can be useful as it is a means of simplifying elements of structures, and this can save time and thus cost. Variations in manufacturing processes and user environment may affect the quality and performance of a product. It is usually beneficial to account for such variances or tolerances in the design process, and in fact, sometimes it may be crucial, particularly when the effect is of consequence. The work conducted within this project focused on methodologies for optimally designing fibre-reinforced laminated composite structures with the effects of manufacturing tolerances included. For this study it is assumed that the probability of any tolerance value occurring within the tolerance band, compared with any other, is equal, and thus the techniques are aimed at designing for the worst-case scenario. This thesis thus discusses four new procedures for the optimization of composite structures with the effects of manufacturing uncertainties included.

scholarly journals Welded joints as critical regions in pressure vessels -case study of vinyl-chloride monomer storage tank

2018 ◽  
Vol 72 (4) ◽  
pp. 177-182 ◽  
Author(s):  
Tamara Golubovic ◽  
Aleksandar Sedmak ◽  
Vesna Spasojevic-Brkic ◽  
Snezana Kirin ◽  
Emil Veg
Keyword(s):  
Vinyl Chloride ◽  
Pressure Vessel ◽  
Welded Joints ◽  
Storage Tank ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Vinyl Chloride Monomer ◽  
Case Scenario ◽  
Worst Case ◽  
Critical Regions

Welded joints are analysed as critical regions in a pressure vessel in respect to structural failure due to the elastic-plastic fracture/crack growth. To assess structural integrity of pressure vessels used in chemical industry the risk based procedure has been introduced and applied in the case of a large spherical pressure vessel used as a vinyl-chloride monomer (VCM) storage tank in HIP Azotara Pancevo. The risk matrix has been used, taking into account the basic definition of risk, being the product of the probability and consequence, and applied to different regions of welded joints, having different mechanical properties, i.e. crack resistance. To estimate probability, the failure assessment diagram (FAD) has been used, as an engineering tool, defined according to the position of the operating point for different regions of the welded joint, relative to the critical point on the limit curve. Generally speaking, consequence is estimated based on pressure vessel parameters, or by detailed analysis of health, safety, business and security issues, but in the analysed case, the worst case scenario is assumed, with the highest consequence due to potential disaster for environment and fatalities.

scholarly journals Disproportionate Collapse Mitigation in Tall Mass Timber Buildings

2019 ◽  
pp. 413-420
Author(s):  
Hossein Daneshvar ◽  
Ying Hei Chui
Keyword(s):  
Urban Areas ◽  
Structural Integrity ◽  
Tall Buildings ◽  
Case Scenario ◽  
Worst Case ◽  
Unique Type ◽  
Structural Robustness ◽  
Concrete Members ◽  
Disproportionate Collapse ◽  
Mass Timber

Tall buildings are a unique type of structure with their own characteristic behaviour. They are most often occupied by a large number of people; therefore, their damage, loss of functionality, or, in worst case scenario, collapse will lead to catastrophic consequences. There are methodologies intended to provide structural integrity or increase structural robustness in tall buildings, thereby making structures resistant to disproportionate collapse, which is characterized by a cascading progression of damage that is not proportionate to the initial failure. Tall buildings are commonly constructed with steel and concrete. As a result, most of the attempts at providing structural integrity are dedicated to mitigating the effect of disproportionate collapse in the steel and concrete members, connections, and their systems. On the other hand, with rising demand for new sustainable buildings in urban areas, tall mass timber buildings have attracted increased attention nationally and internationally. Ease of modularization and offsite construction is one of the greatest advantages of using mass timber in tall building construction in the congested urban areas of major cities. A major challenge facing the engineering community is the lack of research studies regarding the structural robustness required to mitigate the potential of disproportionate collapse. The current study seeks to begin the process of understanding the behaviour of mass timber components and assemblages, and make recommendations regarding their performance and possible means to mitigate the occurrence of disproportionate collapse. These recommendations would lead to safer structural performance in the event of localized damage that has the potential to spread to a disproportionately large part of the structure.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects

EXPEDITION TO MALI, 2020

2020 ◽  
pp. 12-28
Author(s):  
D. V. Vaniukova ◽  
◽  
P. A. Kutsenkov ◽  
Keyword(s):  
Mass Murder ◽  
The State ◽  
Case Scenario ◽  
Worst Case ◽  
Traditional Art ◽  
Peter The Great ◽  
State Museum ◽  
Bobo Dioulasso ◽  
Oriental Studies ◽  
The Village

The research expedition of the Institute of Oriental studies of the Russian Academy of Sciences has been working in Mali since 2015. Since 2017, it has been attended by employees of the State Museum of the East. The task of the expedition is to study the transformation of traditional Dogon culture in the context of globalization, as well as to collect ethnographic information (life, customs, features of the traditional social and political structure); to collect oral historical legends; to study the history, existence, and transformation of artistic tradition in the villages of the Dogon Country in modern conditions; collecting items of Ethnography and art to add to the collection of the African collection of the. Peter the Great Museum (Kunstkamera, Saint Petersburg) and the State Museum of Oriental Arts (Moscow). The plan of the expedition in January 2020 included additional items, namely, the study of the functioning of the antique market in Mali (the “path” of things from villages to cities, which is important for attributing works of traditional art). The geography of our research was significantly expanded to the regions of Sikasso and Koulikoro in Mali, as well as to the city of Bobo-Dioulasso and its surroundings in Burkina Faso, which is related to the study of migrations to the Bandiagara Highlands. In addition, the plan of the expedition included organization of a photo exhibition in the Museum of the village of Endé and some educational projects. Unfortunately, after the mass murder in March 2019 in the village of Ogossogou-Pel, where more than one hundred and seventy people were killed, events in the Dogon Country began to develop in the worst-case scenario: The incessant provocations after that revived the old feud between the Pel (Fulbe) pastoralists and the Dogon farmers. So far, this hostility and mutual distrust has not yet developed into a full-scale ethnic conflict, but, unfortunately, such a development now seems quite likely.

Risk-Based Robust Bidding Strategies for EVs’ Aggregators in Day-ahead Markets with Uncertainty

2020 ◽  
Author(s):  
Ahmed Abdelmoaty ◽  
Wessam Mesbah ◽  
Mohammad A. M. Abdel-Aal ◽  
Ali T. Alawami
Keyword(s):  
Robust Optimization ◽  
Electricity Market ◽  
Real Life ◽  
Optimization Approach ◽  
Case Scenario ◽  
Worst Case ◽  
Bidding Strategies ◽  
Wind Generators ◽  
Proposed Model ◽  
Optimal Bidding

In the recent electricity market framework, the profit of the generation companies depends on the decision of the operator on the schedule of its units, the energy price, and the optimal bidding strategies. Due to the expanded integration of uncertain renewable generators which is highly intermittent such as wind plants, the coordination with other facilities to mitigate the risks of imbalances is mandatory. Accordingly, coordination of wind generators with the evolutionary Electric Vehicles (EVs) is expected to boost the performance of the grid. In this paper, we propose a robust optimization approach for the coordination between the wind-thermal generators and the EVs in a virtual<br>power plant (VPP) environment. The objective of maximizing the profit of the VPP Operator (VPPO) is studied. The optimal bidding strategy of the VPPO in the day-ahead market under uncertainties of wind power, energy<br>prices, imbalance prices, and demand is obtained for the worst case scenario. A case study is conducted to assess the e?effectiveness of the proposed model in terms of the VPPO's profit. A comparison between the proposed model and the scenario-based optimization was introduced. Our results confirmed that, although the conservative behavior of the worst-case robust optimization model, it helps the decision maker from the fluctuations of the uncertain parameters involved in the production and bidding processes. In addition, robust optimization is a more tractable problem and does not suffer from<br>the high computation burden associated with scenario-based stochastic programming. This makes it more practical for real-life scenarios.<br>

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