Study on Fatigue Strength Diagrams of Helical Compression Springs

• Published in: Transaction of Japan Society of Spring Engineers Vol. 2024; no. 69; pp. 63 - 86
• Main Author: Research Committee on Fatigue Strength Diagrams of Helical Compression Springs
• Format: Journal Article
• Language: Japanese
• Published: Tokyo Japan Society of Spring Engineers 31.03.2024; Japan Science and Technology Agency
• Subjects: Compression springs; Compressive strength; Data acquisition; Data analysis; Fatigue life; Fatigue strength; Fatigue tests; Fatugue strength diagram; Helical springs; JIS B-2704-1; Oil tempered wire for valve spring; Round wire helical compression spring; S N diagrams; Safety factors; Statistical analysis
• ISSN: 0385-6917; 1348-1479; 1348-1479
• DOI: 10.5346/trbane.2024.63

The “Research Committee on Fatigue Diagrams of Helical Coil Springs”, which ended its activities in 2015, manufactured various springs and conducted fatigue tests with the aim of investigating the validity of the JIS fatigue diagrams. As a result, it was confirmed that the JIS diagram for fatigue strength after 107 cycles was considerably on the safe side. However, due to the small amount of data on the short lifespan side such as 105 and 106 cycles, it was not possible to reach a conclusion from a statistical analysis perspective. Therefore, this committee set test conditions and acquired fatigue data on the low-life side, which the above-mentioned committee had not been able to obtain sufficiently. In addition, statistical analysis was conducted on the test results and the results were compared with the JIS diagram on the low-life side. As a result, it was confirmed that the 50% breakage probability line for this experiment at 105 and 106 times corresponds to a JIS diagram with a safety factor of 1.4 to 1.8.