scholarly journals Assessment of Material Durability of Steam Pipelines Based on Statistical Analysis of Strength Properties—Selected Models

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3633
Author(s):  
Jarosław Piątkowski ◽  
Bożena Gajdzik ◽  
Aleksander Mesjasz
Keyword(s):  
Tensile Strength ◽  
Vickers Hardness ◽  
Operating Time ◽  
Operational Reliability ◽  
Strength Properties ◽  
Working Time ◽  
Prognostic Models ◽  
Significance Level ◽  
The Impact ◽  
Material Durability

The paper presents a research method concerning the application of statistical prognostic models for assessment of material durability and operational reliability of steel for steam pipelines, whose operation has exceeded the working time of 100,000 h. Decisions on the admission of long-lived materials to work for power industry results from extensive diagnostic examinations are based on the results of tests of mechanical properties, microstructure degradation, and corrosion processes. Considering the economic reasons and available data published in diagnostic reports, the determination of failure-free operating time of steam pipelines is based on the results of static tensile tests—tensile strength (Rm); conventional yield point (Rp); elongation (A) and Vickers hardness (V), correlated with the operating time and the media type (fresh steam and secondarily super-heated steam) for the most sensitive element of a pipeline, namely the elbow. The results of changes in strength properties during operation are presented in the form of graphs of the analyzed material feature vs. operating time in the range from zero hours (for a new material) to 300,000 h, taking into account the impact of random and systematic disturbances within the adopted tolerance limits. It has been found that because of the R2 factor and significance level in the t-Student test for regression and correlation coefficients, exponential, hyperbolic and quadratic models are best fitted to empirical points. Based on the tensile strength results (Rm), it has been found that the forecast time of the steam pipeline ranges from 193,400 to 258,300 h. Taking the yield strength (Rp) into account, it has been ascertained that the time ranges from 225,000 to 293,000 h, and for the working time forecast of steam pipelines based on Vickers hardness results, it ranges from 192,100 to 246,800 h.

scholarly journals Evaluation of the Impact of Organic Fillers on Selected Properties of Organosilicon Polymer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1103
Author(s):  
Sara Sarraj ◽  
Małgorzata Szymiczek ◽  
Tomasz Machoczek ◽  
Maciej Mrówka
Keyword(s):  
Tensile Strength ◽  
Natural Fiber ◽  
Accelerated Aging ◽  
Strength Properties ◽  
Visual Observation ◽  
Walnut Shell ◽  
Pistachio Shell ◽  
Thermoplastic Matrix ◽  
Static Tensile ◽  
The Impact

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

scholarly journals Impact of Design Parameters on the Ratio of Compressive to Split Tensile Strength of Self-Compacting Concrete with Recycled Aggregate

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3480
Author(s):  
Rebeca Martínez-García ◽  
P. Jagadesh ◽  
Gabriel Búrdalo-Salcedo ◽  
Covadonga Palencia ◽  
María Fernández-Raga ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Strength Properties ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Design Parameters ◽  
Fine Aggregate ◽  
Strength Ratio ◽  
Self Compacting Concrete ◽  
Split Tensile Strength ◽  
The Impact

Most concrete studies are concentrated on mechanical properties especially strength properties either directly or indirectly (fresh and durability properties). Hence, the ratio of split tensile strength to compressive strength plays a vital role in defining the concrete properties. In this review, the impact of design parameters on the strength ratio of various grades of Self-Compacting Concrete (SCC) with recycled aggregate is assessed. The design parameters considered for the study are Water to Cement (W/C) ratio, Water to Binder (W/B) ratio, Total Aggregates to Cement (TA/C) ratio, Fine Aggregate to Coarse Aggregate (FA/CA) ratio, Water to Solid (W/S) ratio in percentage, superplasticizer (SP) content (kg/cu.m), replacement percentage of recycled coarse aggregates (RCA), replacement percentage of recycled fine aggregates (RFA), fresh density and loading area of the specimen. It is observed that the strength ratio of SCC with recycled aggregates is affected by design parameters.

scholarly journals Prediction of Strength Properties of Filling Packets in Selected Cooling Towers

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3840
Author(s):  
Monika Chomiak ◽  
Maciej Rojek ◽  
Józef Stabik ◽  
Małgorzata Szymiczek
Keyword(s):  
Tensile Strength ◽  
Cooling Tower ◽  
Operating Time ◽  
Degradation Process ◽  
Strength Properties ◽  
Operating Conditions ◽  
Polymer Materials ◽  
Cooling Towers ◽  
Reference Samples ◽  
Degree Of Degradation

The operating conditions of thermoplastic polymer materials determine the changes in their functional properties. Accelerated aging tests do not give a full picture of the changes taking place in the polymer material, hence the conclusions drawn on the basis of exposure of these materials to damaging effects in real operating conditions are particularly important. The aim of the study was to determine the degree of degradation of polypropylene films used in the drainage blocks of cooling towers in a selected power plant in the Silesian voivodship, which allowed forecasting the operating time over a period of 10 years. A number of 600 mm high drip blocks were tested, on which 300 mm high blocks were mounted. The tests were carried out on films subjected to the aging process in the conditions of continuous operation of a cooling tower (almost 100% humidity). The water flow is accompanied by heat exchange, the side effect of which is deposits formation on the surface of the drip blocks, negatively affecting the operation of the cooling tower. The degree of degradation resulting from operational aging was assessed on the basis of the strength properties determined in the static tensile test, thermogravimetric analysis and FTIR spectra. Changes in properties during operation were determined on the basis of the obtained results of the strength tests, which were compared with the tensile strength and elongation at break of reference samples (not subjected to aging in the operating conditions of cooling tower drip blocks). The obtained results were related to the properties of the reference samples not subjected to the degradation process. Based on the collected data, the tensile strength and deformation at fracture after a 10-year service life were predicted.

The influence of alkaline treatment on acoustical, morphological, tensile and thermal properties of Kenaf natural fibers

2020 ◽  
pp. 152808372094424
Author(s):  
Seyed Ehsan Samaei ◽  
Hasan Asilian Mahabadi ◽  
Seyyed Mohammad Mousavi ◽  
Ali Khavanin ◽  
Mohammad Faridan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Sound Absorption ◽  
Hybrid Composites ◽  
Natural Fibers ◽  
Alkaline Treatment ◽  
Strength Properties ◽  
Absorption Coefficients ◽  
Surface Appearance ◽  
Kenaf Fibers ◽  
The Impact

Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustainable alternative to synthetic fibers has received increasing attention for manufacturing hybrid composites with reasonable acoustical and physical properties. The present study deals with the impact of chemical treatment of Kenaf fibers on the overall properties of hybrid composites fabricated from these fibers. Also, the results from predictive analytical model of sound absorption for these composites were employed for comparison with the experimental findings. Kenaf fibers were treated at room temperature with 6% concentration of sodium hydroxide (NaOH) and 4 h immersion time. Having manufactured the composites with the treated and untreated fibers, the normal sound absorption coefficients and tensile strength properties of these sample composites were determined according to ISO 10534-2 and ASTM C1557 − 14, respectively. The SEM analysis of the treated and untreated fibers revealed that in terms of fiber diameter and morphology the former was thinner and had better surface appearance. The experimental measurement of acoustic absorption coefficients of the composites made of treated fibers demonstrated superior sound absorption properties and tensile strength. The revised empirical models proposed by Delany & Bazley and Garai & Pompoli along with Nelder-Mead simplex method were employed and well predicted the sound absorption coefficients of the sample composites. There was also a fair consistency between the experimental and predicted results.

The ecology of Ramalina menziesii. II. Variation in water relations and tensile strength across an inland gradient

1986 ◽  
Vol 64 (1) ◽  
pp. 6-10 ◽  
Author(s):  
D. W. Larson ◽  
U. Matthes-Sears ◽  
T. H. Nash III
Keyword(s):  
Tensile Strength ◽  
Water Uptake ◽  
Water Relations ◽  
Morphological Variation ◽  
Water Loss ◽  
Strength Properties ◽  
Wetting And Drying ◽  
Drying Characteristics ◽  
The Impact

The lichen Ramalina menziesii Tayl. shows a clear gradient in morphology from coastal to inland sites. Experiments were conducted to evaluate the impact of this morphological variation on water uptake, water loss, and tensile strength properties. The results show that none of these characters is greatly influenced by morphological variation. Artificial loading of thalli with NaCl altered the wetting and drying responses in the same direction as was found in coastal material. This implies that the presence of elevated intrathallus concentrations of NaCl found near the coast is mainly responsible for the small differences in wetting and drying characteristics. It further implies that the morphological variation seen in the field is not an adaptation to the conditions near the coast but, rather, is the imposed result of a permanently moist, cool, and salty environment.

scholarly journals A Proposition for the Estimation of the Maximum Tensile Strength of Variously Charged Nanocellulosic Film Materials Provided by Vacuum Filtration

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 543
Author(s):  
Tom Lindström
Keyword(s):  
Tensile Strength ◽  
Strength Properties ◽  
Vacuum Filtration ◽  
Suggested Procedure ◽  
Maximum Tensile Strength ◽  
Research Activities ◽  
Experimental Laboratory ◽  
Two Measures ◽  
The Impact

This short investigation deals with a review of the tensile strength properties of six different types of nanocellulose films (carboxymethylated, carboxymethylcellulose-grafted, enzymatically pretreated, phosphorylated, sulfoethylated, and alkoxylated nanocellulose films) manufactured using identical protocols and the determination of the apparent nanocellulose yield of the same nanocelluloses and their tensile strength properties at different extents of delamination (microfluidization). The purpose was to test a previously suggested procedure to estimate the maximum tensile strength on these different procedures. A second goal was to investigate the impact of the nanocellulose yield on the tensile strength properties. The investigations were limited to the nanocellulose research activities at RISE in Stockholm, because these investigations were made with identical experimental laboratory protocols. The importance of such protocols is also stressed. This review shows that the suggested procedure to estimate the maximum tensile strength is a viable proposition, albeit not scientifically proven. Secondly, there is a relationship between the nanocellulose yield and tensile strength properties, although there may not be a linear relationship between the two measures.

scholarly journals How do firms adjust production factors to the cycle?

2016 ◽  
Vol 16 (2) ◽  
Author(s):  
Gilbert Cette ◽  
Rémy Lecat ◽  
Ahmed Ould Ahmed Jiddou
Keyword(s):  
Capital Stock ◽  
Operating Time ◽  
Capacity Utilization ◽  
Working Time ◽  
Production Factors ◽  
Multiple Dimensions ◽  
Time Offset ◽  
The Impact ◽  
Time Lead ◽  
Path Factor

AbstractThis paper studies the adjustment of production factors to the cycle taking into account factor utilization in multiple dimensions (labor working time, capital operating time and capital capacity utilization) and examines the impact of obstacles to increasing capital operating time on this adjustment path. Factor utilization adjusts the most rapidly, first through capital capacity utilization and capital operating time and then labor working time. The adjustment is slow for the number of employees and even slower for the capital stock. Obstacles to increasing capital operating time lead to a slower adjustment of capital operating time, offset by a stronger adjustment of capacity utilization.

scholarly journals Inoculation of Austenite Primary Grains in Cast Iron

2014 ◽  
Vol 14 (4) ◽  
pp. 45-48 ◽  
Author(s):  
D. Kopyciński ◽  
E. Guzik ◽  
A. Szczęsny ◽  
J. Dorula ◽  
D. Siekaniec ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Iron Powder ◽  
Strength Properties ◽  
Flake Graphite ◽  
Primary Austenite ◽  
Commercial Inoculant ◽  
Austenite Grains ◽  
The Impact

Abstract The modification is a widespread method of improving the strength properties of cast iron. The impact in terms of increasing amounts of eutectic grains has been thoroughly studied while the issue of the impact on the mechanical properties of primary austenite grains has not been studied in depth yet. The paper presents the study of both aspects. The methodology was to conduct the melting cast iron with flake graphite, then modifying the alloy by two sets of modifiers: the commercial modifier, and a mixture of iron powder with a commercial inoculant. The DAAS test was carried out to identify the primary austenite grains. The degree of supercooling was determined and the UTS test was performed as well. Additionally carried out the metallographic specimen allowing for counting grains. It can be concluded that the introduction of the iron powder significantly improved the number of austenite primary grains which resulted in an increase in tensile strength UTS.

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