M. W. Tofique, A. Löf, C. Millward, Z. Günther. Testing and calculation of impact fatigue strength of Flap-X and SS 716 flapper valve steel grades / trans from Engl. M. A. Fedorova

During the operation of reciprocating compressors, the flapper valve opens and closes under fluid pressure and flow. As it closes, it strikes against the valve seat, generating stresses and noise. This cycle of loading produces bending and impact fatigue stresses in the reed. This load pattern is repeated billions of times during the service life of a compressor and it defines the service life and reliability. The goal of this study was to calculate the impact fatigue strength of the Flap-X and the SS 716 grades and, to provide the compressor manufacturers with the information they can use to specify a steel grade to be used in their compressors, for reliable service. Impact fatigue tests were conducted on a custom-built impact fatigue test rig that used air pulses to produce movement of the reed valves manufactured by a major European compressor manufacturer Nidec Global appliance GmbH, at a frequency of 315 Hz and pulse width of 2,2 milliseconds. The testing was conducted according to the staircase test method detailed in the International Standard SS-ISO 12107:2012. The impact fatigue strength of the Flap-X and SS 716 steel valves was calculated in terms of the impact velocity according to the modified staircase test method in the standard. The test results and their statistical analysis showed that the impact fatigue strength of the Flap-X grade was higher compared to the SS 716 grade. The calculation and testing of the impact fatigue strength of the flapper valve steel grades could help the compressor designers to select the optimum material for their compressor designs, to provide reliable service. The higher impact fatigue strength of the Flap-X grade, lower failure rate and longer impact fatigue life will allow the compressor manufacturers to design thinner valves, as Flap-X can sustain higher impact fatigue stresses reliably for longer time and, at the same time help reduce noise, as thinner valves produce less noise for a given pressure and frequency.

Download Full-text

Testing and calculation of impact fatigue strength of Flap-X and SS 716 flapper valve steel grades

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/604/1/012062 ◽

2019 ◽

Vol 604 ◽

pp. 012062

Author(s):

Muhammad Waqas Tofique ◽

Alexander Löf ◽

Chris Millward ◽

Zippl Günther

Keyword(s):

Fatigue Strength ◽

Impact Fatigue ◽

Steel Grades ◽

Valve Steel

Download Full-text

Fatigue Strength Analysis of S34MnV Steel by Accelerated Staircase Test

Open Engineering ◽

10.1515/eng-2020-0048 ◽

2020 ◽

Vol 10 (1) ◽

pp. 394-400 ◽

Cited By ~ 2

Author(s):

I. M. W. Ekaputra ◽

Rando Tungga Dewa ◽

Gunawan Dwi Haryadi ◽

Seon Jin Kim

Keyword(s):

Standard Deviation ◽

Fatigue Strength ◽

Fatigue Limit ◽

Fatigue Testing ◽

Reliability Estimation ◽

Test Method ◽

Strength Analysis ◽

Staircase Method ◽

Staircase Test ◽

Number Of Cycles

AbstractThis paper presents the reliability estimation of fatigue strength of the material used for crank throw components. The material used for crank throw components is forged S34MnV steel and subsequently heat-treated by normalising and tempering. High cycle fatigue testing under fully reversed cycling (R = −1) was performed to determine the fatigue limit of the material. The staircase test method is used to obtain accurate values of the mean fatigue limit stress until a number of cycles up to 1E7 cycles. Subsequently, the fatigue test results depend strongly on the stress step and are evaluated by the Dixon-Mood formula. The values of mean fatigue strength and standard deviation predicted by the staircase method are 282 MPa and 10.6MPa, respectively. Finally, the reliability of the design fatigue strength in some selected probability of failure is calculated. Results indicate that the fatigue strength determined from accelerated staircase test is consistent with conventional fatigue testing. Furthermore, the proposed method can be applied for the determination of fatigue strength and standard deviation for design optimisation of S34MnV steel.

Download Full-text

Impact Bending Fatigue Strength of Gear Teeth Case-Hardened by Nitriding and Carburizing

Volume 6: 8th International Power Transmission and Gearing Conference ◽

10.1115/detc2000/ptg-14380 ◽

2000 ◽

Author(s):

Koji Maenosono ◽

Akira Ishibashi ◽

Keiji Sonoda

Keyword(s):

Fatigue Strength ◽

Power Transmission ◽

Plasma Nitriding ◽

Impact Fatigue ◽

Gear Teeth ◽

High Tension ◽

High Fatigue ◽

Alloy Steels ◽

Almost All ◽

The Impact

Abstract Almost all gears used for power transmission of automobiles have been case-hardened by carburizing. Recently, strict demand for reducing running noise and vibration from the power transmission gears requires, in most cases, an additional finishing operation such as grinding and/or honing after carburizing. Nitriding is conducted at a temperature of about 820 K which is lower than the transformation temperature, and thus quenching is not required, resulting in smaller heat treatment deterioration. However, nitrided gears hardly used in practice as for power transmission gears. In the present investigation, experiments were conducted, using test gears case-hardened by two different methods, carburizing and plasma-nitriding. Test results showed that the fatigue strength of carburized gears was higher than that of nitrided gears in most cases when the test gears were made from the same steel. However, the impact fatigue strengths of nitrided gears made from a high tension steel with additional alloy elements Mo and V were higher than those of carburized gears made from the carbon and alloy steels which have been, used as for gear material. The other high tension steel containing neither Mo nor V could not bring about a sufficiently high fatigue strength in comparison with the conventional carburized gears. It should be noted that the impact fatigue strength of carburized gears made from the high tension steel was higher than the ones made of conventional carburizing steel.

Download Full-text

Increasing the impact fatigue strength of ring valve plates

Chemical and Petroleum Engineering ◽

10.1007/bf01137837 ◽

1976 ◽

Vol 12 (12) ◽

pp. 1114-1115 ◽

Cited By ~ 1

Author(s):

V. A. Pyshkin ◽

V. A. Yakovlev ◽

V. Yu. Kuznetsov ◽

S. A. Abramenko

Keyword(s):

Fatigue Strength ◽

Impact Fatigue ◽

Ring Valve ◽

The Impact

Download Full-text

Effect of distance between impact point and hole position on the impact fatigue strength of composite laminates

Composite Structures ◽

10.1016/j.compstruct.2017.02.045 ◽

2017 ◽

Vol 168 ◽

pp. 33-39 ◽

Cited By ~ 3

Author(s):

R.A.M. Santos ◽

P.N.B. Reis ◽

M.J. Santos ◽

C.A.C.P. Coelho

Keyword(s):

Fatigue Strength ◽

Composite Laminates ◽

Impact Point ◽

Impact Fatigue ◽

Hole Position ◽

The Impact

Download Full-text

Fatigue life assessment of TTC streetcar concrete pavements

10.32920/ryerson.14665692.v1 ◽

2021 ◽

Author(s):

Bahram Farhang

Keyword(s):

Life Cycle ◽

Service Life ◽

Fatigue Cracks ◽

Fatigue Loading ◽

Life Assessment ◽

Superior Performance ◽

Experimental Program ◽

Impact Fatigue ◽

Construction Methods ◽

The Impact

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.

Download Full-text