Cantilever Type Research Articles

Fatigue Life Behaviour of Nanocomposite Coated Carbon Steel

Abstract Recently, nano-materials have received increasingly more attention for their potential applications as structural and functional materials. The unique mechanical properties of CNTs, their high strength and stiffness and the enormous aspect ratio provide potentials for the improvement of the mechanical properties of structural materials. The aim of this research is to investigate experimentally the effect of nanocom­posite coating on the fatigue life of carbon steel AISI 1045 specimens with different surface finishes. Nanoadhesives of epoxy resin are synthesized and evaluated. They are originally modified by multiwalled carbon nanotubes (MWCNT) with 0.5 wt.-% as reinforcement. Fatigue tests are conducted on the respective specimens by a rotating bending machine of the cantilever type. Comparing the results for specimens coated with 0.5 wt.-% MWCNT-epoxy composition with the base materials it is found that fatigue life increased five times for a roughness of 0.3 µm and three times for an average specimen roughness of 0.8, 1.6 and 2.5 µm, respectively.

Preparation and application of the 3C–SiC substrate to piezoelectric micro cantilever transducers

This study examines the fabrication process and mechanical properties of piezoelectric films with the substrate, which is made from silicon carbide. After depositing the PZT thick film on silicon carbide substrate and silicon substrate respectively, it was shown that silicon carbide substrate formed a stable interface with PZT thick film up to 950 °C, compared with silicon substrate. In addition, the dielectric constant of the PZT thick film sintered at 950 °C on a silicon carbide substrate was 843, and this value was about over 25 % improved value compared with that on a silicon substrate. A thick film piezoelectric micro transducer of a micro cantilever type was fabricated by using a multifunctional 3C–SiC substrate. The fabricated micro cantilever was a micro cantilever with multiple thin films on either silicon or silicon carbide substrate. The piezoelectric thick-film micro cantilever that was fabricated by using a SiC substrate showed excellent mechanical and thermal properties. The piezoelectric micro cantilever on the SiC substrate shows an excellent sensitivity towards the change of mass compared with the piezoelectric micro cantilever on the Si substrate.

Особливості впливу демпфування на коефіцієнт ефективності симетрично-консольного віброізолятора телескопічної стріли автокрана

Influence of damping over the efficiency factor of the symmetric cantilever vibration isolator of the automobile’s crane telescopic boom has been considered. It’s been shown that if all forms of the intermediate mass oscillations of beam type or T-shaped symmetric cantilever vibration isolator are related then realization of vibro-isolated characteristics is possible which has a local minimum of transfer ratio equaled to zero even taking into consideration damping at the operating frequency.

Picosecond pulse generation in a hybrid Q-switched laser source by using a microelectromechanical mirror

We present a novel Q-switched laser source using a micro-optical-electromechanical mirror (MOEM) designed for short pulse emission. It is based on a hybrid configuration including a passively Q-switched microchip laser coupled to a fiber cavity closed by a cantilever type MOEM acting as an active modulator. This specially designed mirror with a single reflecting gold membrane is switched by low bias voltage ~50 V (peak to peak). This device emits pulses at tunable repetition rates up to 1.6 kHz, with ~564 ps duration and 3.4 kW peak power, which constitutes the shortest pulse duration ever reported with MOEMs based pulsed lasers.

Local photoconductivity of microcrystalline silicon thin films excited by 442 nm HeCd laser measured by conductive atomic force microscopy

Microcrystalline silicon (μc-Si:H) thin films were studied by photo-conductive atomic force microscopy (PC-AFM) under top side illumination by HeCd 442nm laser and/or by scattered light of AFM detection diode. In order to make the top side illumination possible, so called “nose” type cantilevers, with the tip at the end of cantilever, were used for local photo-current map measurements. Local current intensity under different illumination is discussed mainly from a point of view of the absorption depth of the used light. Diffusion length of charge carriers ~300nm was estimated from comparison of the current levels under different illumination.

Preliminary Study on the Fretting Wear Reliability of an Annular Nuclear Fuel

Recently, a dual-cooled fuel (i.e. annular fuel) which is compatible with current operating PWR plants has been proposed in order to increase both power densities and safety margins. Due to the design concept that is compatible with current PWR plants, however, when compared with a current solid nuclear fuel it shows a narrow gap between fuel rods and needs to modify spacer grid shapes and their positions. Because a flow-induced vibration by fast primary coolant is inevitable phenomenon, it is necessary to examine the fretting wear behavior between an annular fuel and designed spacer grids. In this study, fretting wear has been performed to evaluate the wear resistance of the annular fuel by using specially designed spring and dimple of spacer grids that have a cantilever type and a hemispherical shape, respectively. At the spring specimen with relatively small stiffness value, fretting wear was initiated at both end regions and then proceeded gradually to center region. Based on the test results, the fretting wear behavior of annular fuel was compared with the current solid nuclear fuel and a comparative factor of its reliability was proposed.

마이크로 머시닝 기술을 이용한 니켈기반의 압전 진동형 에너지 하베스터 제작

Owing to the rapid growth of mobile and electronic equipment miniaturization technology, the supply of micro mobile computing machine has been fast raised. Accordingly they have performed many researches on energy harvesting technology to provide promising power supply equipment to substitute existing batteries. In this paper, in order to have low resonance frequency for piezoelectric energy harvester, we have tried to make it larger than before by adopting nickel that has much higher density than silicon. We have applied it for our energy harvesting actuator instead of the existing silicon based actuator. Through such new concept and approach, we have designed energy harvesting device and made it personally by making with micromachining process. The energy harvester structure has a cantilever type and has a dimension of for length, width and thickness respectively. Its electrode type is formed by using Au/Ti of interdigitate d33 mode. The pattern size and gap size is 50 . Based on the measurement of the nickel-based piezoelectric energy harvester, it is found to have 778 Hz for a resonant frequency with no proof mass. In that resonance frequency we could get a maximum output power of 76 at 4.8 being applied with 1 g acceleration.

Cantilever Based Connector Platform for Exchangeable and Customizable Scanning Probe Tips

Abstract The atomic force microscope (AFM) has become a standard and wide spread instrument for characterizing nanoscale devices and can be found in most of today‘s research and development areas. Within the EU-project “NanoBits”, exchangeable and customizable scanning probe tips are developed. These NanoBits offer a high level of freedom in adapting the shape and size of the tips to the surface topology of the specific application. In order to exchange the NanoBits without changing the cantilever, a special type of cantilever is developed. This cantilever combines the geometric flexibility of a silicon nitride cantilever with the advantages of a silicon connector platform. Besides the cantilever based connector platform, first results of mounting a NanoBit onto the connector platform are also presented. This mounting results in a fixed connection between NanoBit and connector platform but also allows an exchange of the NanoBit when needed.

Piezoceramic Cantilever Sensor Design for Weak-Impact Detection on Plates

A piezoelectric cantilever type sensor for locating the precise weak-impact or touch position on a plate is presented in this paper. Since the importance of human-computer interface such as a touch panel system has been rapidly increasing recently, this study could suggest an appropriate sensor for the detection of a weak-impact point effectively and accurately for such a system. This sensor detects the out-of-plane vibration of a panel when a touch with a finger or pen is applied on it. The sensor is made with a steel beam and a single crystal PMN-PT patch is bonded on the beam, which is designed to detect the base vibration of the panel. The sensor was designed, manufactured to verify the detect ability of a weak-impact and attached on two different plates of a glass of 400 × 400 × 4 mm and a wooden MDF of 600 × 600 × 9 mm. The experiment result of the sensor was compared with that of an accelerometer which can also be used for the same purpose and shows clear weak-impact responses with a narrow-band property at its resonant frequency. It is expected that the cantilever type sensor in this study could be applied to make a simple flat plate into a touch panel when the time difference of arrivals method is used to locate the weak-impact point.

Increase of Generating Power of Cantilever Type Piezoelectric Generators by Interconnecting the Generators

A cantilever-type piezoelectric generator has advantages of simple structure, ease of fabrication and large displacement by transverse vibration of a beam. It is easy to control the natural frequency, and also possible to increase the output power by changing the length, width, and thickness of the generator. In this paper, generators were designed and fabricated to resonate at a frequency of 120Hz, which was a mechanical vibrating frequency of vibrating source (electric transformer). For increasing output power, eight generators were arrayed on parallel lines to form an interdigital shape and the output terminals of each generator were electrically interconnected by a combination of series and parallel circuits. To increase the generating voltage, a series connection of generators was effective while for increasing current, a parallel connection was effective.

215 圧電コンポジットを利用した振動発電装置のエネルギー変換効率の評価(セッション8 エナジーハーベスティングと評価システム技術)

In the previous authors' study, the vibration energy harvester of the piezoelectric bimorph cantilever type was proposed for vibration condition monitoring applications of rotating machinery. Authors assumed that the typical casing or pedestal vibration amplitude of the rotating machinery was 0.71 mm/sec rms and this low intensity excitation condition was the input for experimental evaluation of the voltage generation performance of the piezocomposite vibration energy harvester. Proposed energy harvester consists of the surface bonded two Macro-Fiber Composites (MFCs). In this study, energy transfer efficiency was derived from the system energy balance during the natural period of the proposed vibration energy harvester. Energy balance equations were successfully obtained from the governing equations of the piezoelectrically coupled electro-mechanical system. In this study, the two types of cantilever, milling plate and thin plate, were used for evaluating the effect of the mechanical damping property of the clamped end. The maximum AC power of milling plate through 51.0 Kilo-Ohm resistor which includes instrument internal resistances experimentally obtained 408.8 microwatt at the resonant frequency of the harvester (58.40 Hz). The impedance matching between MFCs and the electrical resistive load was effective for maximizing AC power transfer of the vibration energy harvester. Estimated energy transfer from mechanical system to electrical system shows the agreement with the experimentally evaluated generating power during the natural period of the vibration energy harvester with about 3 (%) difference. Estimated energy transfer efficiency was about 30 % for different excitation magnitudes: 0.71, 0.568, and 0.355 mm/sec rms.

Piezoceramic cantilever sensor design for weak-impact detection on plates

A piezoelectric cantilever type sensor for locating the precise weak-impact or touch position on a plate is presented in this paper. Since the importance of human-computer interface such as a touch panel system has been rapidly increasing recently, this study could suggest an appropriate sensor for the detection of a weak-impact point effectively and accurately for such a system. This sensor detects the out-of-plane vibration of a panel when a touch with a finger or pen is applied on it. The sensor is made with a steel beam and a single crystal PMN-PT patch is bonded on the beam, which is designed to detect the base vibration of the panel. The sensor was designed, manufactured to verify the detect ability of a weak-impact and attached on two different plates of a glass of 400 × 400 × 4 mm and a wooden MDF of 600 × 600 × 9 mm. The experiment result of the sensor was compared with that of an accelerometer which can also be used for the same purpose and shows clear weak-impact responses with a narrow-band property at its resonant frequency. It is expected that the cantilever type sensor in this study could be applied to make a simple flat plate into a touch panel when the time difference of arrivals method is used to locate the weak-impact point.

Study on Energy Transfer Efficiency Analysis of Cantilever Type of Piezocomposit Vibration Energy Harvester (Evaluation of System Energy Balance and Power Generation Efficiency)

Study on Energy Transfer Efficiency Analysis of Cantilever Type of Piezocomposit Vibration Energy Harvester (Evaluation of System Energy Balance and Power Generation Efficiency)

An efficient vibration energy harvester with a multi-mode dynamic magnifier

A novel piezoelectric energy harvester with a multi-mode dynamic magnifier, which is capable of significantly increasing the bandwidth and the energy harvested from the ambient vibration, is proposed and investigated in this paper. The design comprises a multi-mode intermediate beam with a tip mass, called a ‘dynamic magnifier’, and an ‘energy harvesting beam’ with a tip mass. The piezoelectric film is adhered to the harvesting beam to harvest the vibration energy. By properly designing the parameters, such as the length, width and thickness of the two beams and the weight of the two tip masses, we can magnify the motion virtually in all the resonance frequencies of the energy harvesting beam, in a similar way as designing a new beam-type tuned mass damper (TMD) to damp the resonance frequencies of all the modes of the primary beam. Theoretical analysis, finite element simulation, and the experiment study are carried out. The results show that voltage produced by the harvesting beam is amplified for efficient energy harvesting over a broader frequency range, while the peaks of the first three modes of the primary beam can be effectively mitigated simultaneously. The experiment demonstrates 25.5 times more energy harvesting capacity than the conventional cantilever type harvester in the frequency range 3–300 Hz, and 100–1000 times more energy around all the first three resonances of the harvesting beam.

Grid supports design for dual-cooled fuel rods

To enhance fuel safety and to achieve a power uprating, a new concept PWR (Pressurized Water Reactor) fuel, which is called a dual cooled fuel rod, has been studied since 2007. Although there are some challenging problems about each mechanical component, fuel rod supporting structures are especially dealt within this paper. In the dual-cooled annular fuel rod, an inner flow passage as well as an outer one is used not only to enhance the fuel safety but to achieve a power uprating through the decreasing fuel center temperature and increasing the heat transfer area between fuel and coolant. As a result, the diameter of dual-cooled fuel rods becomes 1.6 times bigger than a conventional solid fuel rod and the gap between the annular fuel and the spacer grid’s straps is narrowed. This is a current key issue of fuel rod supports. To accommodate the narrowed gap, spacer grids, such as the cantilever type, hemi-sphere type, circular insertion type, etc., were suggested. For some of these configurations, patents have been applied. The grid springs in a spacer grid play the role of holding the fuel rods in an appropriate position and preventing fuel rods from dropping during normal reactor operation. In the case of the dual cooled fuel rod, the total mass is increased. So, the stiffness of a grid spring has to be increased more than that of a conventional grid spring. However, if the stiffnesses of springs are increased too much, fuel rods can bend due to the prohibition of their axial slip. So, it is necessary to design an appropriate stiffness. In this paper, the minimum spring force to prevent dual-cooled fuel rods from dropping during normal reactor operation is calculated. The spring characteristics of a cantilever type and a hemi-sphere type are predicted. A finite element analysis is carried out by using the commercial code ABAQUS. The analysis results are verified by experiments. Finally, it is checked whether the property of the suggested springs satisfies the minimum required spring force. Based on the obtained results, a kind of spacer grid candidate for dual cooled fuel rods, i.e. a spacer grid with hybrid supports is suggested.

Analysis of the drive shaft fracture of the bucket wheel excavator

Drive in most bucket wheel excavators (BWEs) is accomplished through its electric motor, cardan shaft and planetary gearbox. In the BWE SchRs630/6x25, the planetary gearbox is cantilevered at the end of the hollow shaft which transmits the torque through the sprocket to the caterpillar track chain. In this BWE, the drive shaft fracture occurs at the point of support on the penetration side. Experimental testing of the chemical composition and mechanical properties of the material of the shaft and metallographic inspections of the fracture surface by means of electronic and light microscopes carried out in the first part of the paper have shown that there are no significant inhomogeneities and errors in the material of the shaft and that they do not cause damage. Further, the analysis of results referring to the mechanical properties and chemical composition of the repaired shaft at the point of welding, and particularly in the transition zone, shows that they considerably deviate from those prescribed for the material used. Significant inhomogeneity of the material, occurrence of cracks as well as the difference in the microstructure appear in this zone, which is the cause of shaft damage. The second part of the paper presents the FEM analysis of effects of the cantilever type of support of the planetary gearbox and stress concentration at the point of support due to inadequate finishing, which caused the occurrence of an initial crack. The user unsuccessfully tried to eliminate this weakness by repair welding of the shaft.

Interlaboratory round robin on cantilever calibration for AFM force spectroscopy

Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are frequently used for cantilever calibration, there is no consensus on the optimal calibration of soft and V-shaped cantilevers, especially those used in force spectroscopy. Therefore, in this study we aimed at establishing a commonly accepted approach to accurately calibrate compliant and V-shaped cantilevers. In a round robin experiment involving eight different laboratories we compared the thermal noise and the Sader method on ten commercial and custom-built AFMs. We found that spring constants of both rectangular and V-shaped cantilevers can accurately be determined with both methods, although the Sader method proved to be superior. Furthermore, we observed that simultaneous application of both methods on an AFM proved an accurate consistency check of the instrument and thus provides optimal and highly reproducible calibration. To illustrate the importance of optimal calibration, we show that for biological force spectroscopy studies, an erroneously calibrated cantilever can significantly affect the derived (bio)physical parameters. Taken together, our findings demonstrated that with the pre-established protocol described reliable spring constants can be obtained for different types of cantilevers.

A molecular dynamics simulation study on resonance frequencies comparison of tunable carbon-nanotube resonators

We investigated tunable gigahertz-resonators, which is based on the application of a telescoped double-walled carbon-nanotube that can be used repeatedly and operate at a single frequency or have a relatively narrow frequency range, via classical molecular dynamics simulations of a double-walled carbon-nanotube. Two types of telescoped double-walled carbon-nanotube resonators were compared with each other; one was bridge-type and another was cantilever-type, and one side was connected to a position controller in order to achieve a telescoped carbon-nanotube. The frequency bandwidth of our cantilevered type design can exceed that of the bridged type. Our simulations showed that such a system can tune it up its resonance frequency by controlling the length of oscillating carbon-nanotube resonator.

BOptimizing atomic force microscopy for characterization of diamond-protein interfaces

Atomic force microscopy (AFM) in contact mode and tapping mode is employed for high resolution studies of soft organic molecules (fetal bovine serum proteins) on hard inorganic diamond substrates in solution and air. Various effects in morphology and phase measurements related to the cantilever spring constant, amplitude of tip oscillations, surface approach, tip shape and condition are demonstrated and discussed based on the proposed schematic models. We show that both diamond and proteins can be mechanically modified by Si AFM cantilever. We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces. We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general.

Calculation Method of the Horizontal Displacement on the Multi-Grid Composite Wall-Shear Wall Structure

The multi-grid composite wall-shear wall structure (the hybrid structure discussed in this paper) is a new dual structural system consisting of the multi-grid composite walls and the RC shear walls. Because of the shear deformation of the composite walls subject to arbitrary loads, it is not accurate to calculate the horizontal displacement of the hybrid structure by using the displacement formulations of the frame-shear wall structure. And therefore, a displacement calculation method for the hybrid structure subjected to horizontal loads should be proposed. In this paper, the composite walls are viewed as shear-flexural type cantilever walls and the shear walls as flexural type cantilever walls. Based on the Timoshenko beam theory, the displacement differential equation of the hybrid structure is proposed by the continuum method. The analytical solutions of the displacement equation for the hybrid structure subject to the inverse triangle load are obtained with boundary conditions. The example indicates that the lateral displacement curve of the hybrid structure from the proposed method exhibits a shear-flexural type characteristic in which the shear deformation should not be ignored.