scholarly journals Vacuum Insulation Panels - An Assessment of the Impact of Accelerated Ageing on Service Life

2012 ◽  
Vol 58 (10) ◽  
pp. 598-606 ◽  
Author(s):  
Roman Kunič
Keyword(s):  
Service Life ◽  
Accelerated Ageing ◽  
Vacuum Insulation ◽  
The Impact

scholarly journals Experimental Verification of Theoretical Ageing and Service Life Prediction Model for Vacuum Insulation Panels

2021 ◽  
Author(s):  
Mahsa Nikafkar
Keyword(s):  
Thermal Conductivity ◽  
Service Life ◽  
Accelerated Ageing ◽  
Aging Effects ◽  
Building Sector ◽  
Microporous Silica ◽  
Vacuum Insulation ◽  
Ageing Model ◽  
Innovative Material ◽  
Multiple Variables

Vacuum Insulation Panels (VIPs) are a kind of the super-insulated materials (SIMs). VIPs are innovative material in various fields like the building sector as it encompasses a higher thermal resistance per unit of thickness compared to conventional insulation. To extensively use VIPs in the building sector, comprehensive performance analysis, and their properties such as thermal conductivity valuations are required to be done under simulated conditions to evaluate its longterm performance. However, different VIPs have varying durability, and as it stands, there is no comprehensive understanding of how all VIPs will behave in real conditions. This research investigates the effect of multiple variables (such as temperature, relative humidity) on VIP service life. The purpose of this research is to validate the theoretical ageing model of VIPs. First, the experimental thermal conductivity results from seven samples of three different VIP categories are collected using a heat flow meter. To measure the accelerated ageing results over 25 years, Arrhenius equation is applied. Next, NRC theoretical model is used to predict the ageing response of the samples. Finally, an analytical method is employed to verify and validate this model based on the collected data. Results shows that effect of ageing and environmental temperature have higher impacts on the performance of fibreglass panels than the fumed silicas. Additionally, the aging effects analysis reveals that microporous silica VIP products would maintain their superior thermal performance over time. Keywords: Vacuum insulation panel, Ageing, Thermal conductivity, accelerated ageing, modelling

scholarly journals Experimental Verification of Theoretical Ageing and Service Life Prediction Model for Vacuum Insulation Panels

2021 ◽  
Author(s):  
Mahsa Nikafkar
Keyword(s):  
Thermal Conductivity ◽  
Service Life ◽  
Accelerated Ageing ◽  
Aging Effects ◽  
Building Sector ◽  
Microporous Silica ◽  
Vacuum Insulation ◽  
Ageing Model ◽  
Innovative Material ◽  
Multiple Variables

Vacuum Insulation Panels (VIPs) are a kind of the super-insulated materials (SIMs). VIPs are innovative material in various fields like the building sector as it encompasses a higher thermal resistance per unit of thickness compared to conventional insulation. To extensively use VIPs in the building sector, comprehensive performance analysis, and their properties such as thermal conductivity valuations are required to be done under simulated conditions to evaluate its longterm performance. However, different VIPs have varying durability, and as it stands, there is no comprehensive understanding of how all VIPs will behave in real conditions. This research investigates the effect of multiple variables (such as temperature, relative humidity) on VIP service life. The purpose of this research is to validate the theoretical ageing model of VIPs. First, the experimental thermal conductivity results from seven samples of three different VIP categories are collected using a heat flow meter. To measure the accelerated ageing results over 25 years, Arrhenius equation is applied. Next, NRC theoretical model is used to predict the ageing response of the samples. Finally, an analytical method is employed to verify and validate this model based on the collected data. Results shows that effect of ageing and environmental temperature have higher impacts on the performance of fibreglass panels than the fumed silicas. Additionally, the aging effects analysis reveals that microporous silica VIP products would maintain their superior thermal performance over time. Keywords: Vacuum insulation panel, Ageing, Thermal conductivity, accelerated ageing, modelling

scholarly journals Maintenance Modelling of Ceramic Claddings in Pitched Roofs Based on the Evaluation of Their In Situ Degradation Condition

2020 ◽  
Vol 5 (9) ◽  
pp. 77
Author(s):  
Cláudia Ferreira ◽  
Ana Silva ◽  
Jorge de Brito ◽  
Ilídio S. Dias ◽  
Inês Flores-Colen
Keyword(s):  
Service Life ◽  
Maintenance Strategies ◽  
Total Replacement ◽  
Remaining Service Life ◽  
In Situ Degradation ◽  
Maintenance Policies ◽  
And Performance ◽  
The Impact ◽  
Maintenance Model

Existing maintenance policies have several limitations, mainly due to the lack of knowledge regarding the durability and performance of buildings. Usually, the maintenance policies are insufficiently accurate, neglecting the risk of failure over time and the global costs associated with repairs. In this study, a condition-based maintenance model, based on Petri nets, is proposed to evaluate the impact of three maintenance strategies of ceramic claddings in pitched roofs (CCPR): MS1—only total replacement; MS2—composed of total replacement and minor intervention and MS3—composed of total replacement, minor intervention and cleaning operations. In this study, 146 CCPR were inspected in situ, with a total area of 43,991.6 m2. The remaining service life of the CCPR; the global costs over the claddings’ lifetime (considering inspection, maintenance, replacement and disposal costs); the claddings’ degradation condition and the number of replacements during the time horizon are used to evaluate the performance of the different maintenance strategies through a simplified multi-criteria analysis. The results show that the gains in performance, in terms of expected service life and durability, of the consideration of preventive maintenance actions (minor interventions or cleaning operations) outweigh the increase of the operation costs.

scholarly journals ESTIMATION OF VEHICLE OPERATING TIME TAKING INTO ACCOUNT THE INFLUENCE OF A NUMBER OF FACTORS

2021 ◽  
Vol 1 (37) ◽  
pp. 76-85
Author(s):  
A. Krasheninin
Keyword(s):  
Service Life ◽  
Operating Time ◽  
Material Resources ◽  
Number Of Factors ◽  
Additional Costs ◽  
Definition Of ◽  
Optimal Average ◽  
The Cost ◽  
The Impact ◽  
Standard Service

Modern vehicles operated on the railways of Ukraine have almost exhausted or exceeded their resource. The overuse of financial and material resources for their maintenance continues. The standard service life of vehicles was calculated on stable economic conditions of use of vehicles and their timely updating in process of aging. The service life of modern vehicles is determined by the influence of many factors, the disregard of which can lead to significant costs, even in compliance with the standard service life. For railway transport, these factors need modern clarification, as in operation their service life often exceeds the standard or, as for intermodal transport, the service life does not have a strict justification. Accordingly, the article analyzes the issues of assessing the impact on the service life of vehicles of the components of the cost of its maintenance and average daily mileage. It is shown that, firstly, the definition of the service life of vehicles must be linked to the cost of vehicle development, its creation, testing and production, the cost of operation and storage, as well as additional costs, and secondly , with the optimal average daily mileage, at which all the costs are minimal.

scholarly journals Lifetime Prediction Methods for Degradable Polymeric Materials—A Short Review

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4507 ◽  
Author(s):  
Angelika Plota ◽  
Anna Masek
Keyword(s):  
Polymeric Materials ◽  
Short Review ◽  
Isoconversional Method ◽  
Lifetime Prediction ◽  
Accelerated Ageing ◽  
Radiation Chemical ◽  
Degradation Reactions ◽  
Wlf Model ◽  
Advanced Isoconversional Method ◽  
The Impact

The determination of the secure working life of polymeric materials is essential for their successful application in the packaging, medicine, engineering and consumer goods industries. An understanding of the chemical and physical changes in the structure of different polymers when exposed to long-term external factors (e.g., heat, ozone, oxygen, UV radiation, light radiation, chemical substances, water vapour) has provided a model for examining their ultimate lifetime by not only stabilization of the polymer, but also accelerating the degradation reactions. This paper presents an overview of the latest accounts on the impact of the most common environmental factors on the degradation processes of polymeric materials, and some examples of shelf life of rubber products are given. Additionally, the methods of lifetime prediction of degradable polymers using accelerated ageing tests and methods for extrapolation of data from induced thermal degradation are described: the Arrhenius model, time–temperature superposition (TTSP), the Williams–Landel–Ferry (WLF) model and 5 isoconversional approaches: Friedman’s, Ozawa–Flynn–Wall (OFW), the OFW method corrected by N. Sbirrazzuoli et al., the Kissinger–Akahira–Sunose (KAS) algorithm, and the advanced isoconversional method by S. Vyazovkin. Examples of applications in recent years are given.

scholarly journals Effect of Voids behind Lining on the Failure Behavior of Symmetrical Double-Arch Tunnels

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1321 ◽  
Author(s):  
Zhang ◽  
Ye ◽  
Min ◽  
Xu
Keyword(s):  
Service Life ◽  
Earth Pressure ◽  
Internal Force ◽  
Failure Behavior ◽  
Large Section ◽  
Failure Patterns ◽  
Internal Forces ◽  
Tunnel Safety ◽  
Increasing Demand ◽  
The Impact

The presence of voids behind lining seriously affects the safety of the symmetrical double-arch tunnels during service life. It is essential to find out the impact of voids on tunnel safety due to the increasing demand for the construction and maintenance of symmetrical double-arch tunnels. Model tests and numerical analyses were conducted in this research. The results attained were explored including earth pressure, internal force, and lining failure. Results reveal that the presence of voids has a large influence on the internal force in the lining of symmetrical double-arch tunnels, generally in the form of asymmetrical failure patterns of the lining. The failure patterns of the lining are greatly influenced by the size and location of voids with respect to the symmetrical double-arch tunnel circumference. Significant changes in the lining internal forces were found at the areas in the close vicinity of the void whereas a few changes were found at the bottom of the sidewall, the invert, and the central wall far away from the void. The propagation laws of lining cracks of asymmetrical double-arch tunnels are more complicated than symmetrical tunnels with a void behind the central wall. The location of the initial cracking of symmetrical and asymmetrical double-arch tunnels is the same, while the lining failure of the large-section tunnel is the most complicated.

Structural Impact in FPSO Life Extension: A Class Perspective

2013 ◽  
Author(s):  
Christiane L. Machado ◽  
Sudheer Chand
Keyword(s):  
Service Life ◽  
Oil And Gas ◽  
Structural Response ◽  
Oil And Gas Industry ◽  
Environmental Data ◽  
Life Extension ◽  
Element Analysis ◽  
Actual Performance ◽  
Remaining Service Life ◽  
The Impact

The Offshore Oil and Gas Industry has converted a large number of units from trading tankers and carriers into Floating Production, Storage and Offloading units (FPSOs). Several of these have been moored offshore Brazil during the last 15 years. Following the discovery of offshore pre-salt fields some years ago, demand for FPSOs has increased, and the forecasts for productive field lives have grown. The result of these developments is the need to extend the service lives of existing FPSOs. The main aim of this study is to investigate FPSO structural response to environmental conditions and functional loads, considering the actual available tools for numerical simulations and Rule requirements, which currently are basic requirements for design review for Classification. The procedure was developed from one selected FPSO converted from a trading Very Large Crude Carrier (VLCC) tanker approximately 15 years ago and includes investigation of the impact on hull behavior comparing the motion analyses of the production unit under environmental data and software capabilities available at the period of conversion and actual performance: variances in the environmental (sea scatter diagrams) datasets; updates to Classification requirements for defining offloading conditions, environmental loads, acceptance criteria and remaining fatigue life (RFL); and incorporating the most recent gauged thickness for primary structure. The selected FPSO was evaluated according to prescriptive Rule requirements and also using finite element analysis, taking into account the previous conditions of Classification approval as well as the actual requirements and available data. Structural analysis included one global model and some local refined models to address strength, buckling and fatigue capacity of the typical portions/connections of the hull. The comparisons performed from the results of these analyses are a crucial step toward understanding the structural capacity of the FPSO at the conversion stage, its performance during the last 15 years, and its remaining service life. Differences were tabulated and evaluated so that a more precise level of uncertainty could be achieved for predicting the estimated remaining service life, and consequently, a new and dedicated approach to investigate the existing FPSO fleet is being generated.

Stress Analysis of Grain Steel Silo with Hole

2012 ◽  
Vol 594-597 ◽  
pp. 666-671
Author(s):  
Qi Feng Peng ◽  
Fan Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Service Life ◽  
Circular Hole ◽  
Stress Level ◽  
Vertical Displacement ◽  
Principal Strain ◽  
Element Analysis ◽  
The Impact

The stress of the grain steel silo is complex. Recently, many grain silos scraped during their service life. The results of finite element analysis by COMSOL show that the cause of the structure failure is the stress concentration caused by the expanding of the hole. Analysis on different hole on the wall of the silo and different frame to strengthen the hole was also studied. Considering the impact of the weight of the structure, the pressure and friction force caused by the storage of the grain and wind load. The analysis turn out that, if the frame of the hole is identical, the stress level and the first principal strain in condition of circular hole is lower than that of rectangular condition, and the maximum vertical displacement of circular hole is smaller than rectangular. In addition, if the hole is the same, the stress level and the first principal strain in condition of U-shaped frame is lower than that of square condition, but the maximum vertical displacement U-shaped frame is bigger than square frame. Therefore, we can’t reduse the stress level by strenthening the frame.

Grinding of flat glass with Fe- and Cu-based diamond tools

2016 ◽  
Vol 232 (9) ◽  
pp. 1561-1568 ◽  
Author(s):  
Sabri Ozturk
Keyword(s):  
Service Life ◽  
Glass Plant ◽  
Flat Glass ◽  
Cutting Tools ◽  
Grinding Wheels ◽  
Diamond Grit ◽  
Diamond Tools ◽  
Effective Factor ◽  
The Impact ◽  
Cutting Speeds

Preparation of grinding wheels is the most important effective factor in glass machining. This article presents the comparison of the iron- and copper-based grinding tools. The performance of the tools is investigated based on technical and commercial aspects using same cutting speeds, feeds, and sizes of diamond grits. Scanning electron microscope is used in order to observe the microstructures of cutting tools. The service life of the grinding tools is determined on the production line in a flat glass plant. A lifetime of Fe-based diamond tools is longer compared to the copper-based wheels. The impact of metal bond materials on the service life is examined. The results show that the Fe-based tools are more economical and more useful for grinding of glass. The holding of Fe-based bonding to diamond grit is stronger than the copper-based ones.

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