Estimation of Degradation of Strength Properties of a Material of Structures Intended for a Long Service Life Using a Combination of Mathematical Models and “Practicable” Measurements

2003 ◽  
Author(s):  
V. I. Makhnenko
Keyword(s):  
Service Life ◽  
Mathematical Models ◽  
Strength Properties

scholarly journals Performance of Polymer Concrete Seeded with Steel Fibres and Stone Powder

2019 ◽  
Vol 8 (4) ◽  
pp. 9844-9847
Keyword(s):  
Compressive Strength ◽  
Bisphenol A ◽  
Mathematical Models ◽  
Experimental Work ◽  
Strength Properties ◽  
Polymer Concrete ◽  
Cement Concrete ◽  
Steel Fibres ◽  
Concrete Mix

This paper presents the fiber effect in the polymer concrete. The concrete is prepared with 10% Bethemcharla stone powder as replacement to cement and 10% of Bisphenol-A polymer to the concrete mixes. The fibers were incorporated to the concrete in the proportion of 0,1 and 2% by volume of specimen. The study mainly focused to evaluate compressive, split, shear and flexural strengths of concrete. Tests conducted on cube, cylinder and beam specimens and from the results it is found that, the fiber seeding to mixes enhances the strength properties. In addition to the mixes, plan cement concrete mix without stone powder and polymer is prepared and tested for the same strengths, this mix is considered as reference mix for comparison purpose. For present experimental work few mathematical models are established to assess strengths in association of cube compressive strength.

scholarly journals STRATEGIC PLANNING OF THE ROLLING STOCK IN TRANSPORTATION BY RAIL

Transport ◽  
2002 ◽  
Vol 17 (6) ◽  
pp. 230-233
Author(s):  
Saulius Kaminskas
Keyword(s):  
Service Life ◽  
Mathematical Models ◽  
Rolling Stock ◽  
Maximum Efficiency ◽  
Repair Costs ◽  
Operational Characteristics ◽  
Optimal Service ◽  
Key Factor ◽  
Qualitative Characteristics

Planning the structure and volume of the rolling stock is a key factor of achieving maximum efficiency of transportation by rail as well as forecasting the demand for these it transport facilities. The demand for trains is a time — dependant variable which in each case should be determined by two main approaches. The first method allows us to determine quantitative parameters of rolling stock (i.e. kilometers logged, efficiency, turnover, etc.). The second is based on specially developed mathematical models relying on qualitative characteristics such as relative expenses, efficiency of the particular train, relative expenditure of resources, cost of the trains, etc. Planning the volume of the rolling stock the determination of optimal service life of the trains plays an important role. The calculations involve repair costs, number of overhauls, current expenses and other operational characteristics.

scholarly journals ОПРЕДЕЛЕНИЕ ХАРАКТЕРИСТИК ХИМИЧЕСКИХ ИСТОЧНИКОВ ТОКА С ЦЕЛЬЮ ПОДТВЕРЖДЕНИЯ ВОЗМОЖНОСТИ ИХ ИСПОЛЬЗОВАНИЯ В СОСТАВЕ СИСТЕМ ЭЛЕКТРОСНАБЖЕНИЯ

2018 ◽  
Vol 26 (4) ◽  
pp. 103-109
Author(s):  
В.А. Пырец ◽  
В.С. Рева ◽  
К.Н. Земляной ◽  
О.В. Гаврилов ◽  
К.В. Безручко
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Mathematical Models ◽  
Discharge Capacity ◽  
Storage Battery ◽  
Residual Service Life ◽  
Residual Service

In the article the question definitions of the guaranteed residual service life of the storage battery, which allows you to accurately determine the parameters and characteristics, and also to predict them in the course of its life cycle. One of the methods of confirming the operability of chemical current sources and determining their further failure-free operation is considered, which are accelerated climatic tests. Also shown is the discharge capacity of chemical sources of current in the form of mathematical models, what makes it possible to determine the characteristics of chemical sources of current under normal conditions, and vice versa, when the capacitance is known from measurements of accelerated climatic tests.

Properties of Rolled and Extruded Semiproducts Made of New Al-Cu-Mg-Ag Heat-Resistant B-1213 Alloy

2006 ◽  
Vol 519-521 ◽  
pp. 483-488 ◽  
Author(s):  
I.N. Fridlyander ◽  
V.V. Antipov ◽  
T.P. Fedorenko ◽  
E.G. Jakimova
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Heat Resistance ◽  
Crack Resistance ◽  
Primary Structure ◽  
Elevated Temperatures ◽  
Strength Properties ◽  
Heat Resistant

Main properties and structure of 2 mm thick sheets and 20×100 mm extruded strips made under industrial conditions from Al-Cu-Mg heat-resistant B-1213 alloy with Ag, Cr, Mn and Zr additions were investigated. It was stated that wrought B-1213 alloy semiproducts are superior to analogous semis made of widely used commercial heat resistant AK4-1ch-type alloys (analogues - AU2GN, 2618 alloys) in strength properties and heat resistance characteristics (by 10-20 %) as well as in crack resistance and fatigue life (by 20-40 %). B-1213 alloy is intended for replacement of traditional heat-resistant alloys of system Al-Cu-Mg-Fe-Ni in advanced aircraft primary structure components subjected heating at elevated temperatures (up to 200-250 oC) and allows one to increase weight efficiency, service life and reliability.

scholarly journals Correlating the Strength Properties of Roller Compacted Concrete

2021 ◽  
Vol 3 (1) ◽  
pp. 1-5
Author(s):  
Saad Issa Sarsam
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Mathematical Models ◽  
Concrete Slab ◽  
Strength Properties ◽  
Coefficient Of Determination ◽  
Specific Strength ◽  
Roller Compacted Concrete ◽  
Indirect Tensile

Prediction of the strength properties of roller compacted concrete from mathematical models is significant for rapid decision of the quality of the pavement. In the present assessment, roller compacted concrete slab samples have been prepared in the laboratory using 12 percentage of Portland cement by weight of aggregates. Cube, core, and beam specimens were extracted from the slab samples and tested for compressive, indirect tensile, and flexural strength at the age of 28 days. Strength test results were corelated among each other and mathematical models were obtained. It was observed that low significance of aggregates gradation type on the compressive and tensile strength exists. However, high influence of dense gradation on flexural strength could be detected. The flexural strength of dense graded mixture is higher than that of gap graded mixtures. The compressive strength of gap graded mixture is higher than that of dense graded mixture. It can be concluded that the flexural strength is higher than the tensile strength by (2.17 and 1.24) folds for dense and gap graded mixtures respectively. The compressive strength is higher than tensile strength by (5.72 and 4.87) folds for dense and gap graded mixtures respectively. The compressive strength is higher than the flexural strength by (3.4 and 2.49) folds for dense and gap graded roller compacted concrete respectively. The obtained mathematical models exhibit high coefficient of determination and may be implemented in verification of the specific strength property based on other measured strength properties of roller compacted concrete.

Review of Experimental Models for Confirmation of Mathematical Models of Gears

2008 ◽  
Vol 385-387 ◽  
pp. 345-348
Author(s):  
Boris Aberšek ◽  
Jože Flašker
Keyword(s):  
Mathematical Model ◽  
Service Life ◽  
Mathematical Models ◽  
Complex Structure ◽  
Experimental Methods ◽  
Experimental Models ◽  
Test Pieces ◽  
Properties Of Materials ◽  
The Mathematical Model ◽  
Real Complex

In order to calculate the service life as precisely and reliably as possible we need good mathematical models for describing loading, geometry, properties of materials and fracture mechanics parameters. It can be established whether a mathematical model is precise and reliable only by comparison of results of the method such as analytical methods in case of simple problems and experiment when real complex structure are deal with. Since gears and gearing belong to the second group, by correctly selected and developed test pieces and carefully planned experiments we obtained results with which we confirmed and justified the mathematical model for calculating mentioned parameters. To this end we will show in this paper series of experimental methods and test pieces used on the gears.

Reservation and Development of Rigid Pavement Quality with the Aid of Bacteria

2021 ◽  
Author(s):  
Saad Sarsam ◽  
◽  
Mohammed Sulaiman ◽  
Keyword(s):  
Service Life ◽  
Healing Process ◽  
Strength Properties ◽  
Water Bath ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Rigid Pavement ◽  
Flexure Strength ◽  
Healing Agent ◽  
Wheel Loading

Initiation of Microcracks in rigid pavement usually starts within few hours of casting due to the shrinkage of concrete and casting at hot environment condition. Cracking proceeds and changes to macrocracks throughout the service life of the pavement due to repetitions of compressive, tensile, and shear stress under wheel loading. Such cracking exhibits a durability problem since the ingress of moisture and harmful chemicals such as sulphates and chlorides into the concrete through the cracks can cause premature matrix degradation and corrosion of embedded steel reinforcement at joints, which may result in the decrement of strength and service life. In this work, implementation of self-healing techniques was adopted with the aid of bacteria and healing agent to precipitate CaCo3 on the formed micro-cracks. The precipitation of calcite by continuous hydration of cement helps in production of calcium carbonate precipitation with the help of bacteria. A soil bacterium named Bacillus subtilis was cultured in the laboratory, the concentration of bacteria cell of B. subtilits in normal saline (NaCl, 9 g/l) suspension was 106 cell/ml. Concrete specimens of various type (cube of 100x100x100 mm, cylinder of 100mm diameter and 200mm height, and beam of 100 x 100 x 500 mm) size have been prepared in the laboratory, then separated to three sets. The first set of specimens were subjected to controlled compression and flexure pre-cracking, then subjected to healing and curing in a water bath which contains the prementioned bacteria at 20°C for 7 days. The second set was the control specimens cured in water bath for 7 and 28 days at 20°C. The third set of specimens were subjected to healing and curing in a water bath which contains the prementioned bacteria at 20°C for 7 and 28 days and then tested for compressive, indirect tensile, and flexure properties. It was observed that the healing process provided by the bacteria have improved the overall properties of concrete by (23, 11 and 16) % for compressive, tensile and flexure strength respectively as compared to those of control mixture after 28 days of curing. On the other hand, specimens subjected to controlled pre-cracking exhibit improvement in strength properties after the healing process provided by the bacteria by (28 and 33) % for compressive and flexure strength respectively as compared to those of control mixture after 7 days of curing. It was concluded that spraying of bacterial water for curing the concrete is beneficial and can be considered as sustainable and environment friendly solution for maintenance. Bacteria can reserve, develop and maintain the quality of rigid pavement.

Analysis of the Linear Section Risk Level Including Changes in the Pipe Material Strength Properties during Main Oil Pipeline Operations

2021 ◽  
pp. 7-14
Author(s):  
S.A. Shotskiy ◽  
◽  
S.L. Golofast ◽  
Keyword(s):  
Service Life ◽  
Pipe Steel ◽  
Strength Properties ◽  
Risk Level ◽  
Pipe Material ◽  
Oil Pipeline ◽  
Main Pipelines ◽  
Linear Sections ◽  
Main Oil Pipeline

Strength properties of the pipe material are random variables and have a statistical straggling that differs for pipe products of different grades. Distribution of these properties significantly effects on the results of calculating the current level of strength reliability and risk of linear sections for the main pipelines. The reliability of such calculations results depends not only on the distribution that obeys the strength properties of the pipe material at the surveyed section, but also on the dispersion limits of these properties. At present, the main pipelines have significant service lives. Due to this, when making assessment of the technical condition, safety, and risk level of linear sections, the issue is raised of how stable the distribution is related to the pipe steel strength properties with an increase of the service life for the main pipeline. The results of studies are presented concerning the actual distribution and limits of dispersion for the strength properties of pipe steel grade 17G1S after a long-term operation of the main pipeline. It is established that the regularities and strength properties dissipation limits for the material of a pipe made of the above steel are changing with time. Based on the results of the study, a practical example is considered related to the assessment of the effect of the identified changes on the probability of failure and the risk level for one of sections at the linear part of the main oil pipeline. The results obtained in the work substantiate the need in considering changes in the distribution of strength properties that arises with an increase in the main pipelines service life. The outlined approach allows to increase the reliability of risk assessment results for the main pipelines having long-term service life.

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