Selection of Critical Failure Modes for Service Life Overtesting

1977 ◽  
Vol 14 (5) ◽  
pp. 306-309 ◽  
Author(s):  
A. E. Samsonov
Keyword(s):  
Service Life ◽  
Failure Modes ◽  
Selection Of

A Mathematical Model for Competing Failure Modes in Strain Cycle Fatigue

2006 ◽  
Vol 129 (2) ◽  
pp. 293-303 ◽  
Author(s):  
Gerald T. Cashman
Keyword(s):  
Failure Modes ◽  
High Stress ◽  
Local Strain ◽  
Initiation Site ◽  
Weakest Link ◽  
Strain Relationship ◽  
Powder Metallurgy Alloy ◽  
Link Model ◽  
Cyclic Plastic Strain ◽  
Selection Of

Elevated temperature data for powder metallurgy alloy René 95 generated in vacuum are presented to demonstrate that the life differences observed between surface and internally initiated failures are due to an environmental effect. The transition in behavior from a mode at low stress dominated by internal initiations to a surface dominated mode at high stress is quantitatively described in terms of both a weakest-link model and a local strain relationship. A fatigue failure mechanism is provided that explains that the natural selection of initiation site is based upon the concept that the site displaying the highest local cyclic plastic strain is the location where fatigue initiates.

Sample selection of prognostics validation test based on multi-stage Wiener process

2018 ◽  
Vol 233 (4) ◽  
pp. 605-614
Author(s):  
Zhiao Zhao ◽  
Yong Zhang ◽  
Guanjun Liu ◽  
Jing Qiu
Keyword(s):  
Wiener Process ◽  
Process Model ◽  
Failure Modes ◽  
Early Stage ◽  
Sample Selection ◽  
Degradation Process ◽  
Time Interval ◽  
Degradation Data ◽  
Multi Stage ◽  
Selection Of

Sample allocation and selection technology is of great significance in the test plan design of prognostics validation. Considering the existing researches, the importance of prognostics samples of different moments is not considered in the degradation process of a single failure. Normally, prognostics samples are generated under the same time interval mechanism. However, a prognostics system may have low prognostics accuracy because of the small quantity of failure degradation and measurement randomness in the early stage of a failure degradation process. Historical degradation data onto equipment failure modes are collected, and the degradation process model based on the multi-stage Wiener process is established. Based on the multi-stage Wiener process model, we choose four parameters to describe different degradation stages in a degradation process. According to four parameters, the sample selection weight of each degradation stage is calculated and the weight of each degradation stage is used to select prognostics samples. Taking a bearing wear fault of a helicopter transmission device as an example, its degradation process is established and sample selection weights are calculated. According to the sample selection weight of each degradation process, we accomplish the prognostics sample selection of the bearing wear fault. The results show that the prognostics sample selection method proposed in this article has good applicability.

Prepregs with Long Service Life. 2. Rheokinetic Selection of Industrial Types of Epoxy Resins and Curing Agents

2003 ◽  
Vol 30 (4) ◽  
pp. 25-32
Author(s):  
Yu. N. Smirnov ◽  
S.V. Kruzhkova ◽  
T.E. Shatskaia ◽  
V.I. Natrusov
Keyword(s):  
Service Life ◽  
Epoxy Resins ◽  
Curing Agents ◽  
Selection Of

scholarly journals Modelling the process of technical re-equipment of the MTF with the simultaneous selection of the optimal plan for its operation on the farm

2020 ◽  
Vol 175 ◽  
pp. 13007
Author(s):  
Arthur Alukhanyan ◽  
Olga Panfilova
Keyword(s):  
Service Life ◽  
Optimal Strategy ◽  
Scientific Management ◽  
Agricultural Machinery ◽  
Main Criterion ◽  
Optimal Plan ◽  
Important Prerequisite ◽  
Optimal Service ◽  
Simultaneous Selection ◽  
Selection Of

The article deals with the issues of renovation (renewal) of the agricultural machinery and tractor fleet by developing models for developing an optimal strategy for its technical re-equipment. The optimal service life of machines in operation is considered as the most important prerequisite for the scientific management of such an update. The main criterion for the optimal strategy is the effectiveness of replacing a particular machine with a new one. The relevance of solving this problem is determined by the urgent need to plan the pace of technical re-equipment of the MTF, taking into account the presence of various economic restrictions.

Influence of Frost Damage on Chloride Penetration into Concrete

2016 ◽  
Vol 711 ◽  
pp. 359-366
Author(s):  
Peng Zhang ◽  
Folker H. Wittmann ◽  
Yan Ru Wang ◽  
Tie Jun Zhao ◽  
Guan Ting
Keyword(s):  
Service Life ◽  
Frost Damage ◽  
Chloride Penetration ◽  
Capillary Absorption ◽  
Freeze Thaw ◽  
Durability Design ◽  
Design Service Life ◽  
Before And After ◽  
Deteriorating Process ◽  
Selection Of

In most national and international codes for durability design, service life is estimated after selection of one single and dominant deteriorating process such as carbonation, chloride penetration or frost attack. Application of existing codes has shown, however, that the predicted service life is not reached in practice in most cases. Early damage occurs and as a consequence expensive repair measures become frequently necessary, long before the design service life is reached. One reason for this discrepancy is certainly the fact that in practice each dominant deteriorating process is usually accompanied by other aggravating processes. In this contribution capillary absorption of different types of concrete is studied first. The influence of an increasing number of freeze-thaw cycles on capillary absorption of water is studied first, then chloride penetration before and after exposure to a certain number of freeze-thaw cycles was determined experimentally. It was found that an increasing number of freeze-thaw cycles increases chloride penetration significantly, and hence reduces service life in aggressive environment. It can be concluded that for realistic service life prediction the interaction between frost damage and chloride penetration has to be taken into consideration in regions with low temperatures.

Preview: 1988 MRS Spring Meeting: Bally's ∎ Reno, Nevada Events Scheduled April 4-10

MRS Bulletin ◽  
1988 ◽  
Vol 13 (2) ◽  
pp. 40-43
Author(s):  
David E. Clark ◽  
Clifton W. Draper ◽  
C.T. Liu
Keyword(s):  
Service Life ◽  
High Technology ◽  
Research Society ◽  
Degradation Mechanisms ◽  
Spring Meeting ◽  
Optical Cable ◽  
Materials Research ◽  
Short Courses ◽  
Preliminary Program ◽  
Selection Of

The 1988 Spring Meeting of the Materials Research Society will be held at Bally's in Reno, Nevada, with events spanning April 4-10. Program Chairs David Clark, Clif Draper, and Chain T. Liu have planned the most diversified topical symposia coverage to date. In addition to a thorough examination of the popular and “hot news” areas, the meeting will also offer a selection of intriguing specialty topics never before offered at an MRS meeting. This year's Spring meeting will feature 16 topical symposia, a program of 23 short courses, and an equipment show. Highlights of the symposia are described below. The names of the short courses and equipment exhibitors are listed elsewhere in this issue. For details see the 1988 MRS Spring Meeting Preliminary Program mailed to all MRS members.During the Plenary and Student Awards session, Raymond D. Tuminaro of AT&T Bell Laboratories will present the Plenary Address on “Materials Aspects of the SL Undersea Optical Cable Design.” Tuminaro will focus on the fiber and cable materials, review their vulnerabilities to degradation mechanisms, and explore methods currently being used to assure acceptable performance levels for the projected 25-year service life of these systems.A special feature is being planned for the 1988 MRS Spring Meeting. A major photomicrography exhibition—Microscapes: The Hidden Art of High Technology—will focus on the seldom-seen world of advanced developments in microelectronics and lightwave communications.

scholarly journals Selection of Parameters for Diagnostics of Parts of Cylinder-piston Group of Automotive Diesel Engines

2020 ◽  
Author(s):  
Б.С. Антропов ◽  
В.В. Капралов ◽  
В.В. Гумённый ◽  
В.А. Генералов
Keyword(s):  
Service Life ◽  
Information Value ◽  
Dust Particles ◽  
Inertial Forces ◽  
Oil Consumption ◽  
Automotive Engines ◽  
Piston Group ◽  
Cylinder Piston ◽  
Quality Check ◽  
Selection Of

Детали цилиндропоршневой группы (ЦПГ) определяют ресурс автомобильных двигателей, так как они являются наиболее нагруженными газовыми и инерционными силами, имеющими переменный и знакопеременный характер изменения. К тому же эти детали имеют контакт с горячими газами и атмосферным воздухом, содержащим абразивные частицы пыли, что интенсифицирует их износ. Достоверность диагностирования состояния деталей ЦПГ зависит от информативности выбранных параметров, которыми являются показатели качества работы двигателей. Проверка двигателей из эксплуатации с пробегами, близкими к их ресурсу, на тормозном стенде при работе на номинальном режиме, показала, что самым информативным является расход масла на долив (на угар). Он рекомендован как основной диагностический параметр деталей ЦПГ. Вспомогательными параметрами рекомендуются компрессия и расход картерных газов, которые целесообразно использовать при углублённом диагностировании указанных деталей с целью определения неисправных цилиндров двигателя. Parts of cylinder-piston group determine service life of automotive engines as they are the most loaded gas and inertial forces, having variable and sign-alternating character of change. In addition, these parts have contact with hot gases and atmospheric air containing abrasive dust particles which intensifies their wear. Reliability of diagnostics of CPG parts condition depends on information value of selected parameters which are indicators of engines operation quality. Check of engines out of service with runs close to their service life on the brake stand bench during operation at nominal conditions has showed that the most informative is oil consumption through burning. It is recommended as the main diagnostic parameter of CPG parts. The auxiliary parameters are recommended compression and flow rate of crankcase gases which are useful for deep diagnostics of the specified parts in order to determine faulty cylinders of the engine.

scholarly journals Perencanaan Perawatan Mesin Pump 107 Dengan Metode Reability Centered Maintenance (RCM) di PT. Petrokimia Gresik

2018 ◽  
Vol 1 (02) ◽  
pp. 33-38
Author(s):  
Rezza Wira Utomo
Keyword(s):  
Service Life ◽  
Failure Mode ◽  
Failure Rate ◽  
Failure Modes ◽  
Treatment Method ◽  
Maintenance Scheduling ◽  
Effect Analysis ◽  
Mean Time ◽  
Working Efficiency ◽  
Causes Of Failure

PT. Petrokimia Gresik is one of the largest fertilizer companies in Indonesia, locatedin Gresik, East Java. The pump 107 engine on the Ammonia unit is often damaged due to itslargest size compared to other types of pumps, as well as the result of carrying thick orconcentrated fluid (bluish black) so that it is heavy for the drainage process. The purpose ofthis study is to plan and recommend the proposed treatment method on the pump enginebased on the method used to improve the working efficiency of the pumping machine 107and determine the failure mode and diagnosis of the effects of failure modes that occur in thecomponent. The method used is the Reability Centered Maintenance (RCM) method whichis expected to be able to produce maintenance or maintenance scheduling that is increasinglydirected so that it can improve the performance and efficiency of the engine, reduce repaircosts, and extend the service life of the machine itself. From this study, the results are in theform of Faliure Model And Effect Analysis (FMEA), FMEA table preparation is carried outbased on component function data and maintenance reports which can then be determined byvarious failures resulting in malfunction. From the compilation of FMEA, it can be seenwhat the causes of failure are and what impacts they have caused. Next, the value of MeanTime Between Failure (MTBF) pump 107-JA is 15,829 hours, pump 107-JB is 43,764 hoursand pump 107-JCM is 19,578 hours. Maintainability M (t) or Mean Time to Repair (MTTR)value on pump 107-JA is 2,914 hours, pump 107-JB is 3,411 hours, and pump 107-JCM is3,1 hours, Availability A (t) value is pump 107-JA at 84.44%, pump 107-JB at 92.76% andpump 107-JCM at 86.31%. The last one is found that the failure rate of pump 107-JA is0.063172, pump 107-JB is 0.02284 and pump 107-JCM is 0.051.

Characterization of Two Types of Stainless Steels Recommended for Manufacturing Brine Recirculation Pumps

2010 ◽  
Author(s):  
O. A. Abuzeid ◽  
A. I. Aljoboury ◽  
A.-H. I. Mourad ◽  
A. Alawar ◽  
M. Abou Zour
Keyword(s):  
Corrosion Resistance ◽  
Service Life ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Material Selection ◽  
Electrochemical Tests ◽  
Desalination Plants ◽  
Selection Of

In earlier works, characterization and stress corrosion cracking of casings of brine recirculation pumps, used in desalination plants, had been investigated. These casings which were manufactured from two types of Ni resist ductile irons have been reported to show different service lives. Material selection of casings is believed to be one of possible factors to extend the service life of these pumps. Two types of stainless steels; UNS S31603 and UNS S32750 have been recommended as substitutes to Ni resist ductile irons. In this work, mechanical, metallurgical, and electrochemical tests have been conducted on as received samples, made of these two types of stainless steels. Results have shown considerable higher yield and tensile strengths and corrosion resistance for the UNS S32750 over the UNS S31603. Results have also shown reproduced pitting behavior illustrated by measured pitting potentials and visual observations for UNS S31603 samples. UNS S32750 samples have shown no signs of pitting.

A Few Aspects on Lubricant Selection for Stepless Chain Coverters: Efficiency and Service Life

1992 ◽  
Author(s):  
G. Schönnenbeck
Keyword(s):  
Friction Coefficient ◽  
Service Life ◽  
Standardized Test ◽  
Test Methods ◽  
Long Term Stability ◽  
Friction Disk ◽  
The Individual ◽  
And Control ◽  
Selection Of

Abstract Stepless vehicle drives will assume their place next to automatic switching units throughout the world if they meet their expected fuel-saving potential. This necessitates optimizing the individual components of the CVT as regards their efficiency. The main source of losses are the hydraulic supply units and the losses which result specifically from non-positive transmission. In the case of stepless chain conveners, these result mainly from friction disk deformation. These losses account for 50 to 70 % of total CVT losses. Both loss components are influenced by the lubricant to a significantly greater extent than it would appear at first sight: In the case of fully-hydraulic clamping and control systems, the viscosity and its long-term stability determines the degree of leakage losses and therefore the size of the pump or pump combinations. This applies to pressure levels between 20 and 40 bar. This in turn is directly proportional to the hydraulic losses on the CVT. The friction coefficient of the lubricant determines the level of the necessary clamping forces. These are responsible for friction-disk deformation. Also of importance as far as the selection of lubricant is concerned is its influence on the CVT service life. The critical service life limits for chain converters are chain breakage (not the subject of this report) and evidence of wear, i.e. grey staining, sheave-grooving, pitting, scoring and rocker pin wear. Standardized test methods exist at P.I.V. for both wear manifestations and for the friction coefficient, these tests allowing a targeted selection of lubricants.

Sign in / Sign up

Export Citation Format

Share Document