The B~+ implanted surface region consists of amorphous Ni-B phase, Ni_3B and Ni_4B_3 second phases, and damage structure. The corresponding measurements indicate that both surface micro-hardness and endurance limit of the specimens have increased after implantation. Compared with unimplanted specimens under the same fatigue condition, all implanted specimens show the smallest overall fatigue damage.
A Safety and allowable high-strain formula for band Saw-blades is proposed, according to the endurance limit of alternating stress in unsymmetrical bending (or pulsating) circulation, and comparisons with those formula given in the Japanese Hand-Book of wood Industry(1982)and with high-strain upper limit curve in Kockums Group (sweden) were also observed.
An approximate calculation formula of endurance limit stress of the drillstring at the condition of being eroded by drilling fluid was derived in combination with the basic characteristics of drillstring fatigue rupture and relevant experimental data.
The results of 2-roller contact fatigue test showed that the types of EP-additive used greatly affect the endurance limit of specimen material. Comparing the commercial N220 heavy-duty gear oil containing the modified chlorinated paraffin with that containing the complex additive, the former can improve significantly the contact fatigue strength of the carburized and quenched steel 20CrMnTi lubricated. The boundary lubrication behavior of modified chlorinated paraffin additive is discussed.
Field surveying shows that the rotor's failure of the steam turbine is because of the rotor' S fatigue failure which is caused by the combined stress. Apply the fuzzy mathematics to get the membership function of the endurance limit. Calculating formula of the rotor' s fuzzy reliability was deduced out by using the theory of the fuzzy reliability.
Through metallographic test,mechanical property tests at room temperature and high temperature,carbide analysis,and high temperature endurance limit test,an estimation formula related to working temperature and stress of material is derived to determine the remaining lifetime of 12Cr1MoV steel after long term operation and the spheroidizing level reaches 4 of 4.5 degree.
It is shown that a decrease in their endurance limit in chloride media is determined by their structure, rather than chemical composition and strength.
It is shown that treatment of VT6 alloy with high-frequency currents increases the endurance limit of the zone subjected to strengthening and makes the alloy more resistant to erosion.
Accumulation of fatigue damage of the material is noted to have a significant influence on reduction of the endurance limit.
When the endurance limit (401±91 s) of the voluntary contraction (VC-I) was reached, the triceps surae could be electrically stimulated to the same torque level for an additional 1 min in 10 of the 11 subjects.
At the endurance limit of VC-I, the superimposed twitch was larger than during the unfatigued MVC, while there was no significant difference between the twitch at the endurance limit of VC-II and MVC.