scholarly journals Using Accelerated Tests to Predict Service Life in Highly Variable Environments

2001 ◽  
pp. 396-413 ◽  
Author(s):  
William Q. Meeker ◽  
Luis A. Escobar ◽  
Victor Chan
Keyword(s):  
Service Life ◽  
Accelerated Tests ◽  
Variable Environments

Dynamic Life Prediction of RC Structures on Multi-Environmental Time Similarity Method

2011 ◽  
Vol 255-260 ◽  
pp. 220-224 ◽  
Author(s):  
Wei Liang Jin ◽  
Zhi Yuan Li ◽  
Ju Chen ◽  
Jin Quan Wang ◽  
Xiao Zhou Wang
Keyword(s):  
Service Life ◽  
Natural Environment ◽  
Life Prediction ◽  
Indoor Environment ◽  
Prior Information ◽  
Service Life Prediction ◽  
Accelerated Tests ◽  
Rc Structures ◽  
Similarity Method

Multi-environmental time similarity (METS) stepped forward for solving the key technique of service-life correlation of reinforced concrete (RC) structures exposed in artificially accelerated and real natural environment. Artificially accelerated tests and the similarity relationship between natural and indoor environment are used to estimate the prior information. Inspections of the real structure and concrete specimens are used to update the information and reduce the uncertainty in the service-life prediction. The progress of service-life prediction becomes dynamic and long-term.

scholarly journals Methods for estimating the durability of the needle bearing of the piston head of the connecting rod of a transportation diesel

2021 ◽  
pp. 55-60
Author(s):  
Vadym Mychaylovich Petuhov ◽  
Alexandr Vasilyevich Orobinsky ◽  
Natalya Anatolyevna Aksenova
Keyword(s):  
Diesel Engine ◽  
Service Life ◽  
Test Procedure ◽  
Operating Conditions ◽  
Accelerated Tests ◽  
Connecting Rod ◽  
Design Work ◽  
Engine Operation ◽  
Piston Head ◽  
Rolling Elements

The article presents the results of an experimental study and analytical evaluation calculations to check service life and increase durability of the needle bearing of piston head of connecting rod of a transport diesel engine. The primary reasons for the violation of the nominal operation of the main units of this mechanism have been established. Corresponding recommendations are proposed for carrying out accelerated tests for durability, reducing the thermal loads of the bearing operation and, as a consequence, improving the quality and service life of its entire piston group. Theoretical and experimental methods for determining the nominal life of the needle bearing of the piston head of the connecting rod (PHCR) of a transport diesel engine are proposed. The theoretical methodology allows obtaining reliable values of durability, taking into account the distribution of the working load over the rolling elements, as well as the mobility of the piston pin and sleeve. The performed calculations make it possible to correct and clarify the standard mathematical model for determining the nominal life of the PHCR needle bearing, depending on the distribution of loads on the rolling elements (rollers) under different operating conditions. This experimental technique with an acceleration factor of 10 is based on a twofold increase in the force effect on the elements of the PHCR needle bearing. This was achieved by assembling the bearing using a special technology, which is described in detail in the work. A significant decrease in the thermal effect and a decrease in radial loads on working rollers have been established. For ensure the regular oil supply into bearing during engine operation, a technique was developed to increase the load on the roller in contact zone, which significantly influenced durability and made it possible to conduct accelerated tests with a reliable yield. Its results of operational research and experience in design work correlate and are sufficiently explained by the developed methods, which allows them to be used for the improvement and modernization of connecting rods with needle bearings in PHCR. That is a permission to use these methodic for doing perfect and modern the needle bearing of the connecting-rod piston. Keywords: diesel, test procedure, needle bearing, rollers, piston head of the connecting rod, durability.

The influence of the technical condition of the modernized spray on the service life of a nozzle sprayer of diesel engine

2020 ◽  
pp. 85-91
Author(s):  
Anzor L. Bolotokov ◽  
Valentin P. Lyalyakin
Keyword(s):  
Diesel Engine ◽  
Service Life ◽  
Diesel Engines ◽  
Resistance Coefficient ◽  
Technical Condition ◽  
Research Purpose ◽  
Spray Nozzle ◽  
Accelerated Tests ◽  
Spiral Groove ◽  
Discussion Article

Injectors of diesel engines lose their functionality due to loss of tightness and jamming of the needle of the nozzle sprayer. (Research purpose) The research purpose is increasing the durability of injectors by upgrading the sprayer needle by performing a spiral screw groove on its guiding part. (Materials and methods) The article notes that the screw groove is performed by an elbor cutter on a lathe with the following parameters: an angle of 30 degrees, a radius of 0.133 millimeters, and a length of 21.71 millimeters. Authors conducted research to determine the resistance coefficient of the gap between the sprayer body and the sprayer with a spiral groove, depending on the fuel contamination. Authors performed non-motor bench accelerated tests of sprayers to determine the hydraulic density, the volume of fuel in the screw groove, and the resistance coefficient of the gap. (Results and discussion) Article notes that the decrease rate in the value of hydro density in upgraded sprayers is 1.24 times less than in serial ones. The article shows that due to the screw groove, the needle of the sprayer is rotated, and the working surfaces of the needle are not caught with the sprayer body, which ensures uniform wear with less intensity. (Conclusions) Upgrading the spray nozzle by applying a screw groove to its surface ensures that the surfaces are lubricated and creates a softened twisting impact instead of a hard hit on the spray nozzle seat.

scholarly journals Accelerated testing of track vehicle torsion bar

2020 ◽  
Vol 327 ◽  
pp. 03001
Author(s):  
Jan Furch ◽  
Quy Hung Nguyen ◽  
Jiri Stodola
Keyword(s):  
Finite Elements ◽  
Service Life ◽  
Dynamic Simulation ◽  
Suspension System ◽  
Accelerated Testing ◽  
Virtual Model ◽  
Accelerated Tests ◽  
Adams Software ◽  
Torsion Bar

The suspension system of track vehicles is often equipped with torsion bars. The torsion bar is a key element of the vehicle's suspension system. The service life of torsion bars depends primarily on the quality of the material used, the diameter of the torsion bars and the method of attachment and placement. In order to obtain the characteristics of the torsion bar, an experimental test stand was created on which accelerated tests were performed. Furthermore, a virtual model of torsion bar operation was created. The torsion bar was modelled using finite elements (FE part). Dynamic simulation was performed using MSC Adams software. Finally, the values measured in the accelerated tests and the results of simulations were compared. Comparing the values found, it was proved that this difference is not significant. This virtual model can be used to investigate the service life of torsion bars and to predict their service life.

scholarly journals Lifetime Test of Tracked Vehicle Torsion Bars using Monte Carlo Method

2020 ◽  
Vol 4 (5) ◽  
pp. 376-389
Author(s):  
Jan Furch ◽  
Quy Hung Nguyen
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Finite Elements ◽  
Service Life ◽  
Dynamic Modelling ◽  
Accelerated Tests ◽  
Tracked Vehicle ◽  
Data Set ◽  
Tracked Vehicles ◽  
Torsion Bar

The article deals with the service life of torsion bars in tracked vehicles. The aim of the article is to show the suitability of accelerated tests and modelling for determining the service life of torsion bars, which takes many years in real operation. The design of a test bench for accelerated tests is presented together with limiting conditions, which were afterwards verified. Subsequently, a virtual model of the torsion bar of a tracked vehicle was created with the help of finite elements. Dynamic modelling was performed by MSC Adams software with a module using finite elements. Furthermore, the article shows the possibility of using the Monte Carlo method to determine the service life of torsion bars of tracked vehicles. The Monte Carlo utility of Accelerated Life Testing Analysis (ALTA) software is used to obtain failure data at specified test stress levels. Using the Monte Carlo simulation, one data set is generated containing values that are arranged in dependence on the specific lifetime distribution of the Weibull distribution. Finally, a comparison of the experiment with the calculated values is performed. The results obtained can be used to compile an accelerated test plan. This modelling design saves a lot of money and time to determine the life of the torsion bar in tracked vehicles.

scholarly journals Comparison between Accelerated Tests and Natural Exposures for Organic Coating Protective Systems Based on EIS Parameters

2021 ◽  
Author(s):  
Xingyue Yong ◽  
Haotian Ji ◽  
Zhenning Chen ◽  
Xin Ruan
Keyword(s):  
Service Life ◽  
Low Frequency ◽  
Mathematical Expression ◽  
Organic Coating ◽  
Atmospheric Environment ◽  
Al Alloy ◽  
Accelerated Tests ◽  
Limit Value ◽  
Protective System ◽  
Probability Density Function Pdf

Abstract The equivalent relationship between accelerated tests and natural exposures has been extensively studied over the past several years to estimate the service life of a barrier organic coating protective system. Herein, based on the probability density function (PDF) theory, a mathematical expression that describes the limit value of the low-frequency impedance (RL) of a barrier organic coating protective system as a function of the elapsed time is proposed in form of Arrhenius formula under certain assumptions, and the degradation coefficient is defined. This expression was consistent with the results of the accelerated tests. The equivalent relationship between accelerated tests and natural exposures, established based on the equivalence principle, was utilized to predict the service life of the coated Al alloy in an ocean atmospheric environment.

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