GB/Z 42085-2022 Pneumatic fluid power—Assessment of component reliability by accelerated life testing—General guidelines and procedures (English Version)
Introduction
In a pneumatic system, power is transmitted and controlled by compressed air in a circuit. Pneumatic systems consist of various components and are an important part of all types of machinery and equipment. Efficient and economical production requires highly reliable machinery and equipment.
The reliability of pneumatic components can be evaluated in the laboratory according to the test methods specified in national standards for normal use conditions.
The life of pneumatic components is usually long. In order to quickly grasp their life characteristics, accelerated tests can be performed using overstress to bring forward the failure of the components and to determine the relationship between the reliability of the components under accelerated life tests and the reliability under normal conditions of use.
1 Scope
This document establishes a general procedure for evaluating the reliability of pneumatic components based on accelerated life tests. This document applies to directional valves, cylinders with piston rods, regulators, and components covered by ISO 19973 (all parts).
This document does not establish a specific procedure for accelerated life testing of pneumatic components. This document gives variable conditions in the accelerated life test method for pneumatic components and provides guidance for the development of accelerated life test methods for pneumatic components.
This document applies to the first failure of pneumatic components without maintenance.
2 Normative reference documents
This document has no normative references.
3 Terms and definitions
ISO 5598,ISO 19973-1 defined and the following terms and definitions are applicable to this document.
4 Symbols and units of measurement
5 Reliability and accelerated life test overview
Reliability is the ability of a product to perform the required function under a given condition and within a given time interval. This ability, if expressed in terms of probability, is known as reliability. Reliability is assessed according to the test methods described in ISO 19973 (all parts).
Reliability analysis refers to the analysis of the time or number of cycles that a component fails under normal use conditions to quantify its life characteristics, which are often difficult to obtain.
Since components usually have long lifetimes and the time interval between product design and release is short, in order to observe component failure to better understand its lifetime characteristics, procedures have been devised to accelerate component failure under overstressed conditions, thereby allowing components to fail faster than under normal use conditions, i.e., accelerated life testing (ALT).
The relationship between the reliability of a component under ALT and that under normal use conditions can be determined by comparing the results obtained from the extrapolated ALT with those obtained under normal use conditions, as depicted in Figure 1.
6 Failure mechanism and mode
The failure mechanism refers to the physical or chemical process that causes transient or cumulative damage to the component material. Failure mode refers to the manifestation of the failure mechanism of the component failure or performance degradation. Failure mode is the manifestation of the failure mechanism at the defective part of the component (stress exceeding strength).
The failure mode observed under accelerated life conditions needs to be equivalent to the failure mode defined under normal service conditions.
7 Accelerated life test strategy
Prior to accelerated life testing, determine the types of failures that are likely to occur in the component during use (especially feedback from the field). Quantitative methods for design analysis and review include Quality Function Development (QFD), Fault Tree Analysis (FTA), and Failure Mode and Effects Analysis (FMEA). Qualitative methods include Highly Accelerated Life Testing (HALT). Qualitative tests are mainly used to reveal possible failure modes, but they cannot quantify the life (or reliability) of a component under normal use conditions.
Accelerated life tests promote accelerated failure of components and are designed to quantify the life characteristics of components under normal use conditions.
8 Accelerated life test design
8.1 Normal use conditions
Normal service conditions are usually defined according to the rated requirements of the component characteristics, e.g., pressure, temperature, voltage, operating. Operating cycles, lubrication requirements, etc. However, the rated values are usually higher than the normal use conditions. Therefore, the definition of normal service conditions needs to be determined based on these characteristics prior to accelerated testing. See Table 1 for examples of pneumatic valve definitions.
9 test termination
9.1 Minimum number of failure samples
The number of failures of the component under test at each stress level is at least 4. When the number of samples is not greater than 4, the minimum number of failed samples is the number of samples.
9.2 Number of termination cycles
When the failure of the component under test occurs between successive observations, the data collected is called left truncated or interval data. In this case, the number of cycles at the end of the normal operation of the component under test and the number of cycles at which the failure of the component under test is observed are recorded. This data is usually processed in accordance with 10.2 in ISO 19973-1:2015.
10 Statistical analysis
10.1 Failure data analysis
Failure data for all stress level tests are analyzed according to 10.2 to 10.4.
10.2 Life distribution
The initial life distribution is selected (if necessary, it can be changed later). For pneumatic components, the Weibull distribution is commonly used, and its scale parameter () is selected as the stress-related life characteristic, with the slope () assumed to remain constant at different stress levels.
11 Evaluation of reliability characteristics by test data
12 Test report
Appendix A (Informative) Stress Levels for Time-Dependent Stress Models
Appendix B (informative) Life-stress model
Appendix C (informative) Validation of Weibull slope after compromise
Appendix D (Informative) Computational Procedures for Truncated Data
Appendix E (informative) Examples of accelerated life tests used in industrial applications
Appendix F (Informative) Palmgren-Meiner Law
Appendix G (Informative) Results of accelerated life test for cylinders
Bibliography
Introduction
1 Scope
2 Normative reference documents
3 Terms and definitions
4 Symbols and units of measurement
5 Reliability and accelerated life test overview
6 Failure mechanism and mode
7 Accelerated life test strategy
8 Accelerated life test design
9 test termination
10 Statistical analysis
11 Evaluation of reliability characteristics by test data
12 Test report
Appendix A (Informative) Stress Levels for Time-Dependent Stress Models
Appendix B (informative) Life-stress model
Appendix C (informative) Validation of Weibull slope after compromise
Appendix D (Informative) Computational Procedures for Truncated Data
Appendix E (informative) Examples of accelerated life tests used in industrial applications
Appendix F (Informative) Palmgren-Meiner Law
Appendix G (Informative) Results of accelerated life test for cylinders
Bibliography
Standard
GB/Z 42085-2022 Pneumatic fluid power—Assessment of component reliability by accelerated life testing—General guidelines and procedures (English Version)
Standard No.
GB/Z 42085-2022
Status
valid
Language
English
File Format
PDF
Word Count
22500 words
Price(USD)
675.0
Implemented on
2022-12-30
Delivery
via email in 1~5 business day
Detail of GB/Z 42085-2022
Standard No.
GB/Z 42085-2022
English Name
Pneumatic fluid power—Assessment of component reliability by accelerated life testing—General guidelines and procedures
Introduction
In a pneumatic system, power is transmitted and controlled by compressed air in a circuit. Pneumatic systems consist of various components and are an important part of all types of machinery and equipment. Efficient and economical production requires highly reliable machinery and equipment.
The reliability of pneumatic components can be evaluated in the laboratory according to the test methods specified in national standards for normal use conditions.
The life of pneumatic components is usually long. In order to quickly grasp their life characteristics, accelerated tests can be performed using overstress to bring forward the failure of the components and to determine the relationship between the reliability of the components under accelerated life tests and the reliability under normal conditions of use.
1 Scope
This document establishes a general procedure for evaluating the reliability of pneumatic components based on accelerated life tests. This document applies to directional valves, cylinders with piston rods, regulators, and components covered by ISO 19973 (all parts).
This document does not establish a specific procedure for accelerated life testing of pneumatic components. This document gives variable conditions in the accelerated life test method for pneumatic components and provides guidance for the development of accelerated life test methods for pneumatic components.
This document applies to the first failure of pneumatic components without maintenance.
2 Normative reference documents
This document has no normative references.
3 Terms and definitions
ISO 5598,ISO 19973-1 defined and the following terms and definitions are applicable to this document.
4 Symbols and units of measurement
5 Reliability and accelerated life test overview
Reliability is the ability of a product to perform the required function under a given condition and within a given time interval. This ability, if expressed in terms of probability, is known as reliability. Reliability is assessed according to the test methods described in ISO 19973 (all parts).
Reliability analysis refers to the analysis of the time or number of cycles that a component fails under normal use conditions to quantify its life characteristics, which are often difficult to obtain.
Since components usually have long lifetimes and the time interval between product design and release is short, in order to observe component failure to better understand its lifetime characteristics, procedures have been devised to accelerate component failure under overstressed conditions, thereby allowing components to fail faster than under normal use conditions, i.e., accelerated life testing (ALT).
The relationship between the reliability of a component under ALT and that under normal use conditions can be determined by comparing the results obtained from the extrapolated ALT with those obtained under normal use conditions, as depicted in Figure 1.
6 Failure mechanism and mode
The failure mechanism refers to the physical or chemical process that causes transient or cumulative damage to the component material. Failure mode refers to the manifestation of the failure mechanism of the component failure or performance degradation. Failure mode is the manifestation of the failure mechanism at the defective part of the component (stress exceeding strength).
The failure mode observed under accelerated life conditions needs to be equivalent to the failure mode defined under normal service conditions.
7 Accelerated life test strategy
Prior to accelerated life testing, determine the types of failures that are likely to occur in the component during use (especially feedback from the field). Quantitative methods for design analysis and review include Quality Function Development (QFD), Fault Tree Analysis (FTA), and Failure Mode and Effects Analysis (FMEA). Qualitative methods include Highly Accelerated Life Testing (HALT). Qualitative tests are mainly used to reveal possible failure modes, but they cannot quantify the life (or reliability) of a component under normal use conditions.
Accelerated life tests promote accelerated failure of components and are designed to quantify the life characteristics of components under normal use conditions.
8 Accelerated life test design
8.1 Normal use conditions
Normal service conditions are usually defined according to the rated requirements of the component characteristics, e.g., pressure, temperature, voltage, operating. Operating cycles, lubrication requirements, etc. However, the rated values are usually higher than the normal use conditions. Therefore, the definition of normal service conditions needs to be determined based on these characteristics prior to accelerated testing. See Table 1 for examples of pneumatic valve definitions.
9 test termination
9.1 Minimum number of failure samples
The number of failures of the component under test at each stress level is at least 4. When the number of samples is not greater than 4, the minimum number of failed samples is the number of samples.
9.2 Number of termination cycles
When the failure of the component under test occurs between successive observations, the data collected is called left truncated or interval data. In this case, the number of cycles at the end of the normal operation of the component under test and the number of cycles at which the failure of the component under test is observed are recorded. This data is usually processed in accordance with 10.2 in ISO 19973-1:2015.
10 Statistical analysis
10.1 Failure data analysis
Failure data for all stress level tests are analyzed according to 10.2 to 10.4.
10.2 Life distribution
The initial life distribution is selected (if necessary, it can be changed later). For pneumatic components, the Weibull distribution is commonly used, and its scale parameter () is selected as the stress-related life characteristic, with the slope () assumed to remain constant at different stress levels.
11 Evaluation of reliability characteristics by test data
12 Test report
Appendix A (Informative) Stress Levels for Time-Dependent Stress Models
Appendix B (informative) Life-stress model
Appendix C (informative) Validation of Weibull slope after compromise
Appendix D (Informative) Computational Procedures for Truncated Data
Appendix E (informative) Examples of accelerated life tests used in industrial applications
Appendix F (Informative) Palmgren-Meiner Law
Appendix G (Informative) Results of accelerated life test for cylinders
Bibliography
Contents of GB/Z 42085-2022
Introduction
1 Scope
2 Normative reference documents
3 Terms and definitions
4 Symbols and units of measurement
5 Reliability and accelerated life test overview
6 Failure mechanism and mode
7 Accelerated life test strategy
8 Accelerated life test design
9 test termination
10 Statistical analysis
11 Evaluation of reliability characteristics by test data
12 Test report
Appendix A (Informative) Stress Levels for Time-Dependent Stress Models
Appendix B (informative) Life-stress model
Appendix C (informative) Validation of Weibull slope after compromise
Appendix D (Informative) Computational Procedures for Truncated Data
Appendix E (informative) Examples of accelerated life tests used in industrial applications
Appendix F (Informative) Palmgren-Meiner Law
Appendix G (Informative) Results of accelerated life test for cylinders
Bibliography
