Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films

2007 ◽  
Vol 353-358 ◽  
pp. 299-302
Author(s):  
Jun Hyub Park ◽  
Man Sik Myung ◽  
Yun Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Rf Mems ◽  
Type Specimen ◽  
Fatigue Tests ◽  
Measuring System ◽  
Fatigue Properties ◽  
Test Machine ◽  
Ti Alloy

This paper describes new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a fatigue test. High cycle fatigue test has been performed on tensile type specimen of Al-3%Ti alloy using the newly developed fatigue test machine. The material used in this study was Al-3%Ti thin film, which was used in RF MEMS switch. The structure of the suggested specimen has two holes and several bridges. The holes at centre of grip end are able to make alignment and gripping easy. The bridges are to remove the side support strip easily and extract specimen from wafer without sawing. The test machine was developed using the voice coil of speaker. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Fatigue tests was performed on 7 specimens. The thickness and width of the thin film of specimen are 1.0μm and 150μm, respectively. The fatigue strength coefficient and the fatigue strength exponent of Al-3%Ti alloy micro-sized specimen are determined to be 164MPa and -0.01322, respectively

Effect of Pre-Strain on Fatigue Properties of NHH Rail

2004 ◽  
Vol 261-263 ◽  
pp. 1239-1244
Author(s):  
Wen Xian Sun ◽  
S. Nishida ◽  
Nobusuke Hattori ◽  
X.L. Yue
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Slip Lines ◽  
Propagation Behavior ◽  
Strain Process ◽  
Initiation And Propagation

In the present study, fatigue tests have been performed to study the effect of pre-strain on fatigue properties of NHH (New Head-Hardened) rail. The objectives of this study were: (1) to observe the microscopic behavior of specimens during pre-strain process, (2) to research the influence of pre-strain on fatigue strength of NHH rail and (3) to investigate initiation and propagation behavior of the fatigue crack. The results showed that plastic pre-strain decreased the fatigue strength of NHH rail; fatigue limits had no obvious variation among the different pre-strain ratios. Fatigue cracks initiated in the microscopic cracking or slip lines that were originated in the pre-strain process and propagated from these sites in the later fatigue test.

Fatigue Properties of Nitride Cr-Mo Steel with CrN Thin Film Deposited by Aip Method

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1554-1559 ◽  
Author(s):  
Daisuke Yonekura ◽  
Atsushi Tsukuda ◽  
Ri Ichi Murakami ◽  
Koji Hanaguri
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Compressive Residual Stress ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Three Point Bending

In this study, we selected the nitride Cr-Mo Steel SCM435 as the substrate. Attention was focussed on the effect of film thickness. The Arc Ion Plating was performed using Cr cathode and N2 gas. The specimens were prepared for the film thickness 6, 12 and 18μm The three point bending fatigue tests were performed at room temperature in a laboratory environment. After the fatigue test, crack initiation sites were examined by using an optical microscope and a scanning electron microscope. The results obtained were as follows: (1) A high compressive residual stress generated in the film, and the compressive residual stress of 12μm film thickness was the greatest. (2) The fatigue strength of coated specimens for thin film was slightly lower than for substrate. (3) The film thickness hardly affected the fatigue strength of coated specimens.

Specimen Size Effect on Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films

2007 ◽  
Author(s):  
Jun-Hyub Park ◽  
Man Sik Myung ◽  
Yun-Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Evaluation Method ◽  
High Cycle Fatigue ◽  
Test Procedure ◽  
Fatigue Tests ◽  
Test Method ◽  
Fatigue Properties ◽  
Cycle Fatigue

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone and also describes new test method for obtaining static and dynamic characteristics of thin film and reliability evaluation method on MEMS device with thin film developed by authors. Durability should be ensured for such devices under cycling load. Therefore, with the proposed specimen and test procedure, tensile and fatigue tests were performed to obtain mechanical and fatigue properties. The specimen was made with dimensions of 1000μm long, 1.0μm thickness, and 3 kinds of width, 50, 100 and 150μm. High cycle fatigue tests for each width were also performed, from which the fatigue strength coefficient and the fatigue strength exponent were found to be 193MPa and −0.02319 for 50μm, 181MPa and −0.02001 for 100μm, and 164MPa and −0.01322 for 150μm, respectively. We found that the narrower specimen is, the longer fatigue life of Al-3%Ti is and the wider specimen is, the more susceptible to stress level fatigue life of Al-3%Ti was.

Fatigue Test of Al-3%Ti Using Axial Loading Testing Machine for RF MEMS Switch

2006 ◽  
Vol 110 ◽  
pp. 3-8 ◽  
Author(s):  
Jun Hyub Park ◽  
Chang Seung Lee ◽  
Yun Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Rf Mems ◽  
Testing Machine ◽  
Axial Loading ◽  
Tensile Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Mems Switch

This paper presents high cycle fatigue properties of a Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone. The thickness and width of the thin film of specimen are 1.1μm and 480.0μm, respectively. Tensile tests of five specimens are performed, from which the ultimate strength is found to be 144MPa. High cycle fatigue tests of six specimens are also performed, from which the fatigue strength coefficient and the fatigue strength exponent are found to be 336MPa and –0.1514, respectively.

Thermal Fatigue Properties of the Fin in the Boilers

2007 ◽  
Vol 353-358 ◽  
pp. 315-318 ◽  
Author(s):  
Yukihiro Tokunaga ◽  
Nu Yan ◽  
Daisuke Yonekura ◽  
Riichi Murakami
Keyword(s):  
Heat Transfer ◽  
Fatigue Test ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Test Machine ◽  
Element Analysis ◽  
Heat Transfer Efficiency ◽  
Heating And Cooling

In order to improve the heat transfer efficiency, the fins are commonly used in the industrial boiler in Japan. In actual application, the thermal fatigue due to the cyclic change of temperature usually occurs in the fins. The thermal fatigue tests were carried out by using the thermal fatigue apparatus designed. The designed testing apparatus can apply thermal load to the fin by giving heating and cooling alternatively. The fatigue cracks can be observed in the vicinity of the toe in the thermal fatigue test. The heat transfer coefficient and the thermal stress were calculated by using Finite Element Analysis (FEA) method. The fatigue experiments of the fins were also conducted using electro-hydraulic servo fatigue test machine in the laboratory. The results of thermal fatigue experiments were discussed by comparing with those of the mechanical fatigue experiments.

Fatigue Test of Al-3%Ti Using Axial Loading Testing Machine for MEMS Materials

2005 ◽  
Author(s):  
Jun-Hyub Park ◽  
Hyeon Chang Choi ◽  
Chang Seung Lee ◽  
Sung-Hoon Choa ◽  
Man Sik Myung ◽  
...  
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Testing Machine ◽  
Axial Loading ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Mems Switch

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone. The thickness and width of the thin film of specimen are 1.1 μm and 480 μm, respectively. Tensile tests of five specimens are performed, from which the ultimate strength is found to be 144MPa. High cycle fatigue tests of six specimens are also performed, from which the fatigue strength coefficient and the fatigue strength exponent are found to be 336MPa and −0.1514, respectively.

scholarly journals Effects of thermomechanical history and environment on the fatigue behavior of (β)-Ti-Nb implant alloys

2018 ◽  
Vol 165 ◽  
pp. 06001 ◽  
Author(s):  
André Reck ◽  
Stefan Pilz ◽  
Ulrich Thormann ◽  
Volker Alt ◽  
Annett Gebert ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Grain Structure ◽  
Fatigue Properties ◽  
Β Phase ◽  
Α Phase ◽  
Nb Content ◽  
Implant Alloys

This study examined the fatigue properties of a newly developed cast and thermomechanical processed (β)-Ti-40Nb alloy for a possible application as biomedical alloy due to exceptional low Young’s modulus (64-73 GPa), high corrosion resistance and ductility (20-26%). Focusing on the influence of two microstructural states with fully recrystallized β-grain structure as well as an aged condition with nanometer-sized ω-precipitates, tension-compression fatigue tests (R=-1) were carried out under lab-air and showed significant differences depending on the β-phase stability under cyclic loading. Present ω- precipitates stabilized the β-phase against martensitic α’’ phase transformations leading to an increased fatigue limit of 288 MPa compared to the recrystallized state (225 MPa), where mechanical polishing and subsequent cyclic loading led to formation of α’’-phase due to the metastability of the β-phase. Additional studied commercially available (β)-Ti-45Nb alloy revealed slightly higher fatigue strength (300 MPa) and suggest a change in the dominating cyclic deformation mechanisms according to the sensitive dependence on the Nb-content. Further tests in simulated body fluid (SBF) at 37°C showed no decrease in fatigue strength due to the effect of corrosion and prove the excellent corrosion fatigue resistance of this alloy type under given test conditions.

scholarly journals The Effects of Notches on the Fatigue Strength of Steel Structures

2019 ◽  
Vol 279 ◽  
pp. 02001
Author(s):  
Pavol Juhas
Keyword(s):  
Fatigue Strength ◽  
Steel Structures ◽  
Life Time ◽  
Fatigue Tests ◽  
Constructional Steel ◽  
Fatigue Properties ◽  
Stress Range ◽  
Time Data ◽  
Butt Weld ◽  
Applied Loading

The paper informs about the research devoted to load–carrying capacity, fatigue strength and life–time of welded steel structures. The experimental programme comprises fatigue tests of constructional steel S380 (QStE 380 TM). In the first stage 35 specimens were tested: 9 without any weld connection, 14 with transverse milled butt weld and 12 with transverse rough butt weld. The applied loading in this stage was harmonic with constant stress range. All tests ended by fatigue failure. The second part of the research comprised the tests with block simulated loading with variable stress range. The third part applied continuous recording of stresses and strains in critical sections, that gave information about the local failure development in time. Data sets have allowed to define fatigue properties of investigated steel and degradation effects of used welds including the initiation time of remarkable changes in stress-strain stage expressed through the total kinetic energy. The degradation effects of welds on fatigue strength of structural steels were confirmed, especially it was the case of rough welds - without additional milling. Additionally, the differences in the fatigue curves inclinations were indicated that can depend on the level of fatigue strength. The applied approach gives an opportunity to analyse the effects of actual loading process and improve the methodology of judgement of fatigue strength and life-time of steel elements. Reasonable fatigue properties of this steel suggest it for using also in severe technology structures.

Three Ways of Sampling and Fatigue Test Results of Steel P92

2014 ◽  
Vol 891-892 ◽  
pp. 273-277
Author(s):  
Josef Volák ◽  
Zbynek Bunda
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Energy Industry ◽  
Fatigue Properties ◽  
Test Results ◽  
Steam Turbines ◽  
Standard Samples ◽  
Energy Component

This paper describes the fatigue properties of the steel P92. This material is widely used in the energy industry, especially for pipes and pipe bends of supercritical steam turbines. Steel P92 is alloyed with 2 % of tungsten compared to steel P91. This increases a creep strenght of the material. It is possible to reduce wall thickness of the P92 pipe up to about 20%. Fatigue tests were carried out on standard samples and compared with SFT samples (Small Fatigue Test). Using the device SSam 2 made by company Rolce Royce, it is possible to gently remove a samples from energy component without power plant shutdowns. Consider these correlations, i tis possible to determine mechanical properties of the material from small amount of removed experimental material.

Effects of Overload on Fatigue Strength of SUS316 Having a Crack-Like Surface Defect

2010 ◽  
Author(s):  
Hiroko Oosedo ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Surface Defect ◽  
Compact Tension ◽  
Crack Size ◽  
Fatigue Tests ◽  
Stress Intensity Factor Range ◽  
Bending Fatigue ◽  
Bending Fatigue Test ◽  
Key Factor

The effects of overload on the fatigue strength and threshold stress intensity factor range (ΔKth) in SUS316 were studied. Tensile overload was applied to compact tension (CT) specimens with a large crack and fatigue tests were carried out to determine the ΔKth. Tensile or compressive overload was applied to bending fatigue test specimens with a small crack-like surface defect and fatigue tests were carried out to determine the fatigue limit and ΔKth. It was found that the ΔKth increased by tensile overloading. The increasing rate of ΔKth in the CT specimen is larger than that in the bending fatigue test specimen. Thus, the crack size effects on the improvement of ΔKth after overloading were observed. The results are discussed from the viewpoint of fracture mechanics. The size of compressive residual stress is the key factor of the increasing rate.

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