Fatigue testing of bulk materials using a microsystems based approach

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 000632-000664
Author(s):  
Li-Anne Liew ◽  
David T. Read ◽  
Nicholas Barbosa
Keyword(s):  
Thin Films ◽  
Fatigue Testing ◽  
Structural Materials ◽  
Critical Issue ◽  
Fatigue Properties ◽  
Metal Foil ◽  
Bulk Materials ◽  
Test Technique ◽  
Specimen Handling ◽  
Test Instrument

Fatigue, the degradation of a material's mechanical properties due to cyclic loading, is a critical issue limiting the reliability of structural materials[1]. Fatigue testing of materials is typically carried out in controlled laboratory conditions on specially prepared specimens, and the results are extrapolated to real world conditions. In the past two decades, conventional fatigue testing machines and specimens have undergone miniaturization for the purpose of evaluating the fatigue properties of miniaturized mechanical components such as sensors and biomedical implants, with the smallest test specimens having dimensions on the order of 1 mm length [2] or consisting of foils and wires [3]. Challenges with miniaturization include difficulty in specimen handling, gripping, and alignment. At the same time, MEMS technology has been used to fabricate the actuators and sensors for fatigue testing of thin films [4]. In this approach, the specimen is typically part of the MEMS actuator and is fabricated in-situ. While this eliminates the problems with specimen gripping and alignment, it limits the specimen materials to those from which MEMS actuators and sensors can be readily fabricated, is destructive to the MEMs device, and furthermore is typically limited to thin films. We seek to use the advantages of MEMS to study the fatigue properties of bulk materials rather than thin films, but at the micrometer scale. This allows for greater accuracy and spatial resolution, compared to the state of the art, of property measurements of structural materials such as aluminum and stainless steel alloys as well as other materials used in civil infrastructure, aerospace, transportation and energy industries. Our approach is to use MEMS as chip-scale re-useable test instruments into which small specimens cut from bulk materials can be inserted and tested [5]. We describe the design of the MEMS test instrument and the metal foil specimen, whose gage section was 135 um wide and 25 um thick. The test instrument was fabricated from silicon and glass wafers, and the specimens were etched from commercially available Al 1145 H19 foil. Our S-N curve agrees within expectation with published values for similar aluminum alloys tested using conventional methods at much larger specimen size scales, and the fracture surface shows distinct regions corresponding to slow and fast crack growth. We envision this test technique as a tool to further the study of the fatigue properties of structural materials.

Bend testing of micro-scale bulk metal specimens using a chip-scale test instrument

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 000827-000864
Author(s):  
Li-Anne Liew ◽  
David T. Read ◽  
Nicholas Barbosa
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Flexural Stiffness ◽  
Bulk Materials ◽  
Test Chip ◽  
Bend Testing ◽  
Micro Scale ◽  
The Past ◽  
Test Instrument ◽  
Size Scales

We describe bend testing on micro-scale specimens of 302 stainless steel, using a MEMS test instrument. Bend testing is a common way of measuring the flexural stiffness of structural materials across many size scales, from thin laminate sheets to large weldments. Whereas the stiffness of a material under tensile loading is given by the Young's Modulus, the flexural stiffness, or the stiffness in bending, is much lower. In the past two decades, conventional materials testing machines and the specimens themselves have undergone miniaturization for the purpose of evaluating the mechanical properties of miniaturized mechanical components such as sensors and biomedical implants, for which the smallest specimen dimension is typically around 1 mm [2]. Another driver for miniaturizing the testing apparatuses is to test materials with inherently small form factors such as wires and thin films [3]. Now the emerging 3D printing technology is creating another need for material property measurement at micrometer size scales, to accurately capture the property gradients resulting from the layered manufacturing. However, with ever increasing miniaturization comes increasing difficulty in specimen handling, gripping, and alignment. Concurrently, MEMS technology has been used over the past 2 decades to fabricate small actuators and sensors for mechanical testing of materials of thin films [4] or nanoscale materials such as nanowires. We seek to use the advantages of MEMS to study the mechanical properties of bulk materials rather than thin films, but at the micrometer scale. We believe this will result in greater accuracy and spatial resolution of property measurements of structural materials used in civil infrastructure, aerospace, transportation and energy industries, as well as characterizing manufacturing processes that lead to steep property gradients such as 3D printed components. Our approach is to use MEMS actuators as chip-scale re-useable test instruments into which small specimens sectioned from bulk materials can be inserted and tested [5], to reduce the cost and time to obtain large data sets and to allow the measurements to be done in-situ in harsh environments. We will describe the design of a micro-size 302 stainless steel specimen, and the use of a MEMS test instrument for performing the bend testing on the specimens. The specimen's gage section was 350 um long, 65 um wide and 25 um thick, and was made by lithographic etching of a foil. The MEMS test instrument was fabricated from silicon and glass wafers. The specimens were inserted into the MEMS test chip and the silicon actuator applied static bending loads to the specimen. Displacements were measured from optical microscope images, and the force was calculated from the applied voltage and the known (measured) stiffness of the silicon actuator. The applied force from the MEMS actuator was measured directly, without any specimen, using a custom table-top force probe and load cell apparatus, and was in agreement with the force calculated from the applied voltage. The flexural stiffness of the micro specimens were measured, using the MEMS test device, at 90 – 130 N/m. These values were validated by independently testing the specimens with the much larger table-top force probe. We thus show that our MEMS test chip can be used to perform bending tests on micro scale specimens of bulk materials, but with a 1000-fold reduction in size compared to table-top force-measuring apparatuses.

Resonant Fatigue Testing of Cantilever Specimens Prepared from Thin Films

2008 ◽  
Vol 1139 ◽  
Author(s):  
Kwangsik Kwak ◽  
Masaaki Otsu ◽  
Kazuki Takashima
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Cantilever Beam ◽  
Microelectromechanical Systems ◽  
Fatigue Testing ◽  
Crystalline Silicon ◽  
Gold Foil ◽  
Fatigue Properties ◽  
Mems Devices ◽  
Testing Method

AbstractFatigue properties of thin film materials are extremely important to design durable and reliable microelectromechanical systems (MEMS) devices. However, it is rather difficult to apply conventional fatigue testing method of bulk materials to thin films. Therefore, a fatigue testing method fitted to thin film materials is required. In this investigation, we have developed a fatigue testing method that uses a resonance of cantilever type specimen prepared from thin films. Cantilever beam specimens with dimensions of 1(W) × 3(L) × 0.01(t) mm3 were prepared from Ni-P amorphous alloy thin films and gold foils. In addition, cantilever beam specimens with dimension of 3(L) × 0.3(W) × 0.005(t) mm3 were also prepared from single crystalline silicon thin films. These specimens were fixed to a holder that is connected to an golddio speaker used as an actuator, and were resonated in bending mode. In order to check the validity of this testing method, Young's moduli of these specimens were measured from resonant frequencies. The average Young's modulus of Ni-P was 108 GPa and that of gold foil specimen was 63 GPa, and these values were comparable with those measured by other techniques. This indicates that the resonance occurred theoretically-predicted manner and this testing method is valid for measuring the fatigue properties of thin films. Resonant fatigue tests were carried out for these specimens by changing amplitude range of resonance, and S-N curves were successfully obtained.

FIB-Based Fatigue Testing of Silicon Nitride Thin Films for Space Applications

2004 ◽  
Vol 851 ◽  
Author(s):  
Wen-Hsien Chuang ◽  
Rainer K. Fettig ◽  
Reza Ghodssi
Keyword(s):  
Thin Films ◽  
Silicon Nitride ◽  
Focused Ion Beam ◽  
Fatigue Testing ◽  
Ion Beam ◽  
Fatigue Properties ◽  
Test Duration ◽  
Electrostatic Actuator ◽  
Space Applications ◽  
James Webb Space Telescope

ABSTRACTA novel micro-scale electrostatic actuator has been designed and fabricated to study fatigue properties of low-stress LPCVD silicon nitride thin films, which are the structural materials of microshutter arrays to be used in NASA's James Webb Space Telescope (JWST). To obtain different stress levels without high applied voltages, the electrostatic actuator was designed based on a resonant technique to achieve mechanical amplification. All fabricated devices were tested inside a focused-ion-beam (FIB) system with pressure of 10-6 torr at room temperature (23 ± 1 °C) and with the test duration ranging from 5 seconds to 8.5 hours, 105 to 109 cycles, respectively. From the experiment, no fatigue failure of low-stress LPCVD silicon nitride thin films has been observed up to 109 testing cycles, four orders of magnitude higher than the expected lifetime of the microshutter arrays. The presented test device and experimental technique can be extended to characterize fatigue properties for other thin film materials.

Low Cycle Tension-Tension Fatigue Properties of 316L Stainless Steel Thin Sheets

2011 ◽  
Vol 138-139 ◽  
pp. 832-835
Author(s):  
Yong Jie Liu ◽  
Qing Yuan Wang ◽  
Ren Hui Tian ◽  
Xiao Zhao
Keyword(s):  
Stainless Steel ◽  
Room Temperature ◽  
316L Stainless Steel ◽  
Fatigue Testing ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Thin Sheets ◽  
Effect Factor ◽  
Mechanical Fatigue ◽  
Tensile Fatigue

In this paper, tensile fatigue properties of 316L stainless steel thin sheets with a thickness of 0.1 mm are studied. The tests are implemented by using micro mechanical fatigue testing sysytem (MMT-250N) at room temperature under tension-tension cyclic loading. The S-N curve of the thin sheets descends continuously at low cycle region. Cyclic σ-N curve and ε-N curve are obtained according to the classical macroscopical fatigue theory. The results agree well with the experimental fatigue data, showing that the traditional fatigue research methods are also suitable for description of MEMS fatigue in a certain extent. The effect factor of frequency was considered in this study and the results show that the fatiuge life and the fatigue strength are increased as loading frequency increasing.

Structural analysis of Cu 1−x Ag x GaSe 2 bulk materials and thin films

2000 ◽  
Vol 361-362 ◽  
pp. 130-134 ◽  
Author(s):  
M.E Beck ◽  
T Weiss ◽  
D Fischer ◽  
S Fiechter ◽  
A Jäger-Waldau ◽  
...  
Keyword(s):  
Thin Films ◽  
Structural Analysis ◽  
Bulk Materials

A HYBRID MODEL ON HYSTERESIS LOOP AND COERCIVITY IN NANOSTRUCTURED PERMANENT MAGNETS

2006 ◽  
Vol 05 (04n05) ◽  
pp. 627-631 ◽  
Author(s):  
M. J. SUN ◽  
G. P. ZHAO ◽  
J. LIANG ◽  
G. ZHOU ◽  
H. S. LIM ◽  
...  
Keyword(s):  
Thin Films ◽  
Domain Wall ◽  
Grain Boundary ◽  
Magnetic Moment ◽  
Permanent Magnets ◽  
Hysteresis Loops ◽  
Bulk Materials ◽  
Rotational Model ◽  
Moment Distribution ◽  
Coercivity Mechanism

A simplified micromagnetic model has been proposed to calculate the hysteresis loops of nanostructured permanent magnets for various configurations, including thin films, exchange-coupled double-layer systems and bulk materials. The reversal part of the hysteresis is based on the Stoner–Wohlfarth coherent rotational model and the coercivity mechanism is due mainly to the motion of the transition region (a domain wall like magnetic moment distribution in the grain boundary). The elements of nucleation and pinning models are also incorporated.

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

scholarly journals Determining the Nitrogen Content in (Oxy)Nitride Materials

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1331 ◽  
Author(s):  
Franck Tessier
Keyword(s):  
Thin Films ◽  
Nitrogen Content ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Extraction Techniques ◽  
Bulk Materials ◽  
Wavelength Dispersive Spectroscopy ◽  
Oxygen Determination ◽  
Carrier Gas Hot Extraction ◽  
Large Panel

Nitrogen (and also oxygen) determination has become an important parameter to characterize (oxy)nitride materials for many properties and applications. Analyzing such anions with accuracy is still a challenge for some materials. However, to date, a large panel of methodologies is available to answer this issue with relevant results, even for thin films. Carrier gas hot extraction techniques and electron probe microanalysis with wavelength dispersive spectroscopy (EPMA-WDS) look attractive to analyze bulk materials and thin films, respectively. This paper gathers several techniques using chemical and physical routes to access such anionic contents. Limitations and problems are pointed out for both powders and films.

Transmission Electron Microscopy Study of Mod Plzt and Pnzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Jhing–Fang Chang ◽  
Chi Kong Kwok ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Curie Temperature ◽  
Dopant Concentration ◽  
Microscopy Study ◽  
Lattice Parameter ◽  
Electron Microscopy Study ◽  
Bulk Materials ◽  
Thin Foils ◽  
Transmission Electron ◽  
Coating Method

AbstractBoth La and Nd–doped PZT, i.e., PLZT and PNZT, ferroelectric thin films were prepared by the metalorganic deposition (MOD) process. The precursor solutions used were derived from lead acetate, lanthanum acetylacetonate, neodymium acetate, zirconium n–propoxide, and titanium iso–propoxide. The dopant concentration of the films analyzed by electron microprobe indicated a one–to–one correspondence between film composition and the composition of the precursor from which the film was made. In this study, the effects of Nd and La dopants in PZT films on Curie temperature was determined by in–situ hot–stage TEM and compared with those of bulk materials. Lattice parameter and phase transformation were determined by both X–ray and electron diffraction. Our observations were: (1) Curie temperature decreases with increasing dopant concentration for both thin foils and bulk ceramics, (2) for a given dopant concentration, Curie temperature and crystal tetragonality of PNZT thin foils is lower than those of PLZT samples, (3) Curie temperature of thin foils was found to be less than those of the corresponding bulk materials, and (4) ferroelectric domains is easily observed in both PLZT and PNZT TEM specimens prepared by the spin–coating method.

Fatigue of Metal Free Reed due to Self-Excited Oscillation

2008 ◽  
Vol 33-37 ◽  
pp. 267-272
Author(s):  
Yoshinobu Shimamura ◽  
Keiichiro Tohgo ◽  
Hiroyasu Araki ◽  
Yosuke Mizuno ◽  
Shoji Kawaguchi ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
The Self ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Metal Free ◽  
Mass Damper ◽  
Excited Oscillation ◽  
Analytical Research ◽  
Fatigue Characteristics ◽  
Good Agreement

Metal free reeds are used for musical instruments like harmonica. Free reeds are small, thin cantilevers, and oscillate by blowing air. It is reported that free reeds break due to fatigue during play. In order to elongate the life of free reeds, the fatigue properties should be investigated and a motion analysis method should be developed. The experimental and analytical research on metal free reed, however, has been rarely reported. In this study, two types of fatigue testing machines were developed to obtain basic fatigue characteristics. The fatigue testing machines are designed for bending fatigue of actual free reeds whose thickness is less than 400 μm. An S-N diagram is successfully obtained up to 107 cycles by using the developed fatigue testing machines. The fracture surfaces of fatigued specimens are in good agreement with those of free reeds failed in use. Then, an analytical method for the self-excited oscillation of free reeds was developed based on a mass-damper-spring model. The proposed method can take account for the shape of free reed. The self-excited oscillation of free reeds with different shape are analyzed and in good agreement with experimental results.

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