Study on the Bending Fatigue Properties of Nomex Fiber

2014 ◽  
Vol 1048 ◽  
pp. 62-65
Author(s):  
Guang Ming Cai ◽  
Xin Wang
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Testing ◽  
Ccd Camera ◽  
Fracture Morphology ◽  
Fatigue Properties ◽  
Bending Angle ◽  
Bending Fatigue ◽  
Different Temperatures ◽  
Bending Fatigue Strength

In this paper, we reported a bending fatigue testing apparatus which can test the bending fatigue properties of single Nomex fiber by setting the pretension, bending angle and temperature. The S-N and θ-N curves indicated that the pre-tension and bending angle had great influences on the bending fatigue life of Nomex fiber. A CCD camera was utilized to allow observation of the bending fatigue fracture morphology of fiber. It showed the fracture mechanism of Nomex fibers. The bending fatigue life of Nomex fiber was tested at different temperatures to show that its bending fatigue strength is strongly influenced by the temperature.

The Evaluation of Bending Fatigue Testing of Austempered Ductile Iron Spur Gear

2019 ◽  
Author(s):  
Qi Zhang ◽  
Jianhua Lv ◽  
Rizwanulhaque Syed ◽  
Jing Zhang ◽  
Yang Xu ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Ductile Iron ◽  
Fatigue Testing ◽  
Spur Gear ◽  
Austempered Ductile Iron ◽  
Spur Gears ◽  
Reliability Design ◽  
Bending Fatigue ◽  
Bending Fatigue Strength ◽  
Number Of Cycles

Abstract An experimental evaluation of bending fatigue strength for austempered ductile iron (ADI) spur gears have been performed using Zwick fatigue tester. The gear material was manufactured by vertically continuous casting, in which the radius of the graphite grains is smaller. The Stress-Number of Cycles curve (S-N curve) for the bending fatigue strength of the ADI spur gears are manufactured without any specific surface treatments, and have been obtained by post-processing software. It was observed that when the reliability was 50%, the fatigue limit was 304.89 MPa. It has provided a reliable basis to rate the reliability design of the small gearboxes in automation later.

Study on Rotating Bending Fatigue Property of Ti65 Titanium Alloy

2016 ◽  
Vol 849 ◽  
pp. 347-352
Author(s):  
Xu Wang ◽  
Si Qing Li ◽  
Jing Nan Liu
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Notched Specimens ◽  
Different Temperatures ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

The rotating bending fatigue properties of Ti65 titanium alloy blisk forging was studied in the present investigation. The smooth and notched specimens were prepared to test the fatigue properties at room temperature and 650°C. Meanwhile, the influences on rotating bending fatigue of temperature and type were analyzed. Furthermore, the fractural morphology was observed through scanning electron microscopy. The results showed that the medium fatigue strength of Ti65 titanium alloy decreased at 650°C compared with that at room temperature, and the fatigue strength of notched specimens indicated the same significant declination at different temperatures compared with smooth specimens. At room temperature the medium fatigue strength of smooth and notched are 473MPa and 173MPa, respectively, and the fatigue notch sensitive coefficient was 0.87. At 650°C the medium fatigue strength of smooth and notched specimens are 427MPa and 168MPa, where the fatigue notch sensitive coefficient was 0.78.

Finite Fatigue Life Distributions of SAE 1008 Subjected to Various Load-Time Histories

1980 ◽  
Vol 102 (1) ◽  
pp. 135-140 ◽  
Author(s):  
H. A. ElMaraghy ◽  
J. N. Siddall
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Narrow Band ◽  
Fatigue Properties ◽  
Load History ◽  
Random Load ◽  
Bending Fatigue ◽  
Theoretical Predictions ◽  
Time Histories ◽  
Life Distributions

The probabilistic fatigue properties of SAE 1008 steel were determined experimentally. A flexural bending fatigue testing program was carried out consisting of: (a) constant strain amplitude, (b) blocks of Hi-Lo and Lo-Hi-Lo strain amplitudes, and (c) narrow band random load history. Fatigue life of 30-45 specimens in each program were recorded and used to construct distributions of fatigue life. A computer simulation technique was used to predict these distributions. Experimental results and theoretical predictions are both presented for comparison.

A Study on the Development of Mach Peening for Prolonging Fatigue Life of Machine Structural Alloy Steel

2008 ◽  
Vol 580-582 ◽  
pp. 621-624
Author(s):  
Bok Kyu Lim
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Alloy Steel ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Light Weight ◽  
Structural Alloy ◽  
Bending Fatigue

The light weight components, crucial in automobiles and machinery, is require hight strength. Mach peening process is one of many of techniques utilized for improving fatigue properties. From the results of rotary bending fatigue tests, the fatigue strength increases up to 129% in mach peening specimen compared with un-peening. A layer of highly compressed residual stress is obtained by mach peening. The compressive residual stress, induced by mach peening, seems to be an important factor for increasing the fatigue strength.

Effect of metal and polymer mating gears on the bending fatigue performance of asymmetric polymer gears

2021 ◽  
pp. 146442072110033
Author(s):  
A Karthik Pandian ◽  
Sachin Singh Gautam ◽  
S Senthilvelan
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Operating Temperature ◽  
Load Sharing ◽  
Dissipated Energy ◽  
Analysis Tool ◽  
Bending Stress ◽  
Bending Fatigue ◽  
Significant Difference ◽  
Bending Fatigue Strength

The material of the mating gear influences the fatigue life of polymer gears. The bending fatigue characteristics of polyamide 66 asymmetric gears (34°/20° and 20°/34°) corresponding to steel–polymer and polymer–polymer material combinations were investigated. The performance of symmetric gear pairs (20°/20°) was determined to serve as a comparison. Quasi-static numerical simulations were performed in a finite element analysis tool to predict root bending stress, load sharing ratio, and tooth deflection. The bending fatigue strength of steel–polymer and polymer–polymer pairs of each test configuration was determined using bending fatigue tests. The load sharing ratio and root bending stress of polymer–polymer pairs decreased substantially compared to steel–polymer pairs. The extent of deflection-induced load sharing was greater in polymer–polymer pairs. The bending fatigue life of polymer–polymer pairs was lower than that of steel–polymer pairs owing to the higher operating temperature. In polymer–polymer pairs, polymer driving and driven gears increased the heat generated and diminished the heat dissipation to the environment. In steel–polymer and polymer–polymer pairs, the configuration with the highest bending fatigue strength was 34°/20° and 20°/34°, respectively. This divergence was caused by the increase in temperature difference between the two configurations for polymer–polymer pairs. Analysis of hysteresis loops indicated that the loop area was higher for polymer–polymer pairs, signifying the increased amount of dissipated energy. No noticeable variation was observed between the failure modes of steel–polymer and polymer–polymer pairs despite the significant difference in the operating temperatures. The bending stress and operating temperature were the dominant factors affecting the performance of steel–polymer and polymer–polymer gear pairs, respectively.

Comparative bending fatigue strength of precision forged spur gears

1997 ◽  
Vol 211 (4) ◽  
pp. 293-299 ◽  
Author(s):  
O Eyercioglu ◽  
D Walton ◽  
T A Dean
Keyword(s):  
Fatigue Strength ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Spur Gears ◽  
Test Fixture ◽  
Bending Fatigue ◽  
Gear Teeth ◽  
Root Area ◽  
Bending Fatigue Strength

To determine the bending fatigue strength of precision forged spur gears and to compare the results with those obtained from conventional cut gears, single tooth bending fatigue tests were carried out on both through-hardened and induction-hardened gear teeth. The gears were produced from rolled bar cut blanks, disc forged blanks or precision forged teeth blanks. For this purpose, a special test fixture was designed and built for an Amsler high-frequency vibrophore fatigue testing machine. The results show that the endurance limit of precision forged gears is significantly higher than those obtained from cut gears. The bending fatigue strength of forged gears was some 12.5 per cent higher than the cut teeth in a through-hardened condition and 8.4 per cent higher for the induction-hardened teeth. The effect of surface roughness at the tooth root area on the bending fatigue strength of the forged gears is also shown.

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