Cantilever Type Research Articles

薄板ばね特性試験機の試作

A cantilever type apparatus employed to examine the spring elastic limit, Kb of a steel plate with a thickness up to 0.1mm.1) The Kb for specimens with thickness of 0.1mm and 0.2mm were comparable to the values obtained by the APT type machine at the test condition of L≈100t.2) The Kb for ultra thin steel plates could be measured by the present testing machine as well.

Behavior of Roof Deck Diaphragms under Quasistatic Cyclic Loading

A series of 18 large-scale tests was carried out on corrugated cold-formed steel deck diaphragms for single-story buildings to investigate the diaphragm’s ability to function as the main source for absorbing earthquake induced energy through inelastic behavior. Tests were performed using a cantilever type configuration for the test setup, in which the steel deck was laid in a horizontal plane. Diaphragm assemblies made with 0.76 and 0.91 mm thick metal deck sheets and with nine combinations of deck-to-frame and deck-to-deck (side lap) fasteners were tested. For each fastening combination, two tests were conducted: monotonic and quasistatic cyclic. Both the strength and failure modes under quasistatic cyclic loading are different from those under monotonic loading. Test results indicate that diaphragms with welded deck-to-frame fasteners without washers have limited ductility and cannot sustain cyclic loading at relatively large displacement amplitudes. The use of mechanical and welded-with-washer deck-to-frame fasteners enhances the strength, ductility and energy dissipation characteristics of the diaphragm considerably.

The influence of tip performance on scanning probe lithography

Scanning probe lithography (SPL), employing the tip of an atomic force microscope to mechanically pattern various materials in nanoscale region has provided a simple but significant method for making nanostructures. We use this technique for the lithography of several kinds of substrate surfaces. The tip performance has been found to be a crucial factor in the lithographic process. Four types of cantilevers are employed in nanolithography, including standard silicon nitride (DNP), tapping mode™ etched silicon (TESP(W)), uncoated silicon cantilever (NSC21/50) and conductive platinum/iridium-coated probe. Results demonstrate that tips with smaller spring constants can not be used for physically scribing and nanomanipulating in our experiment. The possible mechanism of our experiment is discussed.

Study of Probes and Substrates for Low Temperature Atomic Force Microscopy and Biological Applications

The atomic force microscopy in ultrahigh vacuum and at low temperature demonstrated its excellent capability to reach atomic resolution. Nevertheless in the case of biological samples high resolution has been achieved only in very few cases. We demonstrated here the importance of the appropriate choice of probes and substrates in order to image DNA at low temperature with high resolution. We investigated properties of three types of cantilevers and they were studied by scanning electron microscopy as a function of temperature. A large bending of cantilevers, which were coated from both sides, was observed at low temperatures. Therefore uncoated cantilevers pare strongly recommended for low temperature applications. Different methods for immobilization of DNA on the substrate are examined at low temperatures. First images of linear DNA on graphite at 82 K under ultrahigh vacuum conditions are presented.

Experimental Investigation of Reduced Beam Section Connections by Use of Web Openings

Since the 1994 Northridge Earthquake, a wide variety of different moment connections have been developed to provide high ductility and reliable performance. Most of these moment connections incorporate the reinforcement at the connection using cover plates, ribs or haunches (Engelhardt, Sabol, Aboutaha, and Frank, 1995; Engelhardt and Sabol, 1998; Uang and Bondad, 1996; Uang, Bondad, and Lee, 1998; Whittaker and Gilani, 1996). The purpose of the reinforcement at the connection was to force the plastic hinge away from the face of the column, where premature fractures can occur due to potential weld defects, stress concentrations, etc. The reinforced connections generally showed good performance. However, reinforcing the connection may increase its fabrication costs. Moreover, there were some concerns with respect to reliability resulting from the very large weld for reinforcement. A total of six large-scale tests were performed on single cantilever type test specimens. The specimens were subjected to slowly applied cycles of loads. A test program was conducted on Reduced Beam Section connections by use of beam web openings. The test specimens showed good performance overall, although yielding occurred at lower levels of rotation and strength degradation was worse than for reduced beam flange type connections (dogbone connections).

VIBRATION ANALYSIS OF CANTILEVER TYPE CRACKED ROTOR IN VISCOUS FLUID

The increasing utilisation of rotors in industries and other fields require interpretation of their vibration characteristics and failure conditions. Therefore, computer programmes that have been used will have to be constantly updated. This paper deals with the cantilever type rotor containing a transverse crack subjected to viscous medium. Damping effect and virtual mass effect are taken into account through Navier Stokes equation. The stiff-ness of the cracked shaft is evaluated from the theory of fracture mechanics. For analysis rotor with different crack depth, subjected different viscous medium is considered. The numerical result obtained from theoretical analysis is compared with the experimental results, which agree well.

Electrostatic actuation of thin-film microelectromechanical structures

Microbridge and cantilever electrostatic actuators are fabricated using thin film technology and surface micromachining at low temperatures (⩽100 °C) on glass substrates. Electrostatic actuation is accomplished by applying a voltage, combining a dc component to a low frequency ac component, between the microstructure and an underlying gate counterelectrode. The movement is optically detected by focusing a laser beam on the top of the structure and monitoring the deviation of the reflected light, which is proportional to the electrostatically induced deflection. The absolute value of the deflection is obtained using a calibrated piezoelectric actuator sample holder. The response of the structure is measured with a precision better than 5 Å. The deflection of the microstructures is studied as a function of the magnitude of the electrostatic load, and of the type (bridge or cantilever) and geometrical dimensions of the structure. The mechanical movement is analyzed using an electromechanical model and mechanical properties, such as the microstructure boundary conditions and the materials’ Young’s modulus in the microstructures, are extracted. Nonlinear effects characteristic of electrostatic deflection are observed at high magnitude electrostatic loads. In addition, nonlinear effects due to mechanical stiffening of the microstructures are also observed near the pull-in voltage.

Threshold and growth mechanism of fatigue cracks under mode II and III loadings

ABSTRACT The fatigue crack growth behaviour of 0.47% carbon steel was studied under mode II and III loadings. Mode II fatigue crack growth tests were carried out using specially designed double cantilever (DC) type specimens in order to measure the mode II threshold stress intensity factor range, ΔKIIth. The relationship ΔKIIth > ΔKIth caused crack branching from mode II to I after a crack reached the mode II threshold. Torsion fatigue tests on circumferentially cracked specimens were carried out to study the mechanisms of both mode III crack growth and of the formation of the factory‐roof crack surface morphology. A change in microstructure occurred at a crack tip during crack growth in both mode II and mode III shear cracks. It is presumed that the crack growth mechanisms in mode II and in mode III are essentially the same. Detailed fractographic investigation showed that factory‐roofs were formed by crack branching into mode I. Crack branching started from small semi‐elliptical cracks nucleated by shear at the tip of the original circumferential crack.

Implant-supported fixed cantilever prostheses in partially edentulous arches. A seven-year prospective study.

The purpose of the following study was to evaluate the medium- to long-term prognosis of implant-supported cantilever fixed prostheses, and to establish to what degree this is influenced by factors such as length, type of cantilever (mesial or distal), and opposite dentition versus cantilever prostheses. This study was performed on a sample of 38 partially edentulous patients treated between January 1994 and March 2001 with 49 partial cantilever fixed prostheses supported by 100 implants. Marginal bone resorption (MBL) has been studied and used as a reference parameter to define therapeutic success. The MBL measurement was made possible by transposing X-ray images of patients selected on a PC and then using a software program. Statistical analysis was carried out for possible correlation between peri-implant bone resorption and the parameters considered in this study: length and type (mesial or distal) of cantilever and opposite dentition to cantilever prostheses. Seven years after loading cantilever prostheses, the overall cumulative implant survival rate (OCSR) was 97%, and the prostheses success rate is 98%. Mesial cantilever prostheses registered a lower success rate (97.1%) than distal cantilever prostheses (100%). Furthermore, a better prognosis was not observed when the opposite dentition of the prostheses comprised natural teeth, or fixed prostheses on natural teeth, when compared with the cases in which opposite teeth were implant-supported fixed prostheses. The authors concluded that medium-term prognosis of implant-supported cantilever fixed prostheses and traditional implant-supported fixed prostheses was comparable. However, a thorough pre-treatment analysis of risk factors regarding implant-supported prosthesis survival is important.

Sensors for scanning probe microscopy

Scanning probe microscopy is still suffering from reproducible fabrication of the corresponding sensors for mechanical, electrical, optical, thermal and chemical material characterisation with highest lateral and/or time resolution. For batch-fabrication techniques lithographic, dry etching and material problems have to be solved. Using such techniques, several types of cantilevers and tips including piezoresistive detection systems have been demonstrated world-wide for the first time. Only an overview is given here.

Fabrication of carbon nanotube lateral field emitters

We report on the fabrication and field emission of carbon nanotube lateral fieldemitters. Due to its high aspect ratio and mechanical strength, we use verticallyaligned multi-wall carbon nanotubes prepared by plasma-enhanced chemical vapourdeposition as cathodes, which makes the fabrication of cantilever type lateral fieldemitters possible. The emission characteristics show that the field emissioninitiates at 11–17 V. The device has high geometrical enhancement factors (9.3 ×106 cm−1) compared to standard Spindt tips, which may be due to increased fieldconcentration at the nanotube tip and the close proximity of the anode (<1μm).The relative ease of fabrication compared to vertical field emitters and enhancedfield emission characteristics observed makes the carbon nanotube lateral fieldemitter a good candidate for future integrated nano-electronic devices.

753 圧電素子を用いたスマートワッシャによるボルト締結体の緩み検知

The objective was to apply a structural health monitoring concept to detect loosening of a bolt without human involvement. This paper proposes a new method of a bolt loosening detection by adopting a smart washer which uses a piezoelectric material. The proposed washer is a cantilevered plate type patched piezoelectric material. A self-sensing and actuation function featuring this material is applied to the washer. An explanation that natural frequency decreases with decrease of the bolt tightening axial tension by using the system identification, the concept of the proposed method and experiments verifying its effectiveness are described. The natural frequency of the smart washer was identified with sub-space state space identification method. There was good correlation between the change of the natural frequency of the smart washer system and the decrement of bolt tightening axial tension.

603 部分空間同定法を適用したスマートワッシャによるボルト緩み検知法

The objective was to apply a structural health monitoring concept to detect loosening of a bolt without human involvement. This paper proposes a new method of a bolt loosening detection by adopting a smart washer which uses a piezoelectric material with sub-space state spacce identification algorithm (4SID). The proposed washer is a cantilevered plate type patched piezoelectric material. A self-sensing and actuation function featuring this material is applied to the washer. An explanation that natural frequency decreases with decrease of the bolt tightening axial tension by using the system identification, the concept of the proposed method and experiments verifying its effectiveness are described. The natural frequency of the smart washer was identified with sub-space state space identification method. There was good correlation between the change of the natural frequency of the smart washer system and the decrement of bolt tightening axial tension.

201 スマートワッシャによるボルト締結体の緩み検知

The objective was to apply a structural health monitoring concept to detect loosening of a bolt without human involvement. This paper proposes a new method of a bolt loosening detection by adopting a smart washer which uses a piezoelectric material with sub-space state spacce identification algorithm (4SID). The proposed washer is a cantilevered plate type patched piezoelectric material. A self-sensing and actuation function featuring this material is applied to the washer. An explanation that natural frequency decreases with decrease of the bolt tightening axial tension by using the system identification, the concept of the proposed method and experiments verifying its effectiveness are described. The natural frequency of the smart washer was identified with sub-space state space identification method. There was good correlation between the change of the natural frequency of the smart washer system and the decrement of bolt tightening axial tension.

730 高強度鋼の長寿命疲労特性に及ぼす表面処理の影響

In order to investigate the fatigue properties of high strength steels and surface hardened steels in the super-long life range (N&ge;1×(10)^7), cantilever type rotating bending fatigue tests were carried out for 2 kinds of SNCM 439 steels, which the cleanliness was different on these steels. Also, the surface of notch bottom was removed up to 30μm deep by electro-polishing, because the depth of compression residual stress in the notch bottom of grinding specimen has been 8μm. As a result of fatigue tests, in the case of SNCM 439 (D material) speciem and "high stress amplitude & short life area", it was found that the fatigue life of electro-polishing specimen were almost equal to that of grinding specimen, and in the case of SNCM 439 (S material) speciem and "low stress amplitude & long life area", it was found that the fatigue life of electro-polishing specimen were shorter than that of grinding specimen.

Whirl Vibration Control of Spindle by Using Tuned Mass Damper

This paper proposes whirl vibration control of winder by using a tuned mass damper (TMD). The winder has a cantilever type spindle that is supported at one end and free at the other. Due to the long length of the spindle, amplitude of vibration increases at critical speed. Because of winding up a synthetic fiber to the spindle, there is no space to mount the TMD to the outside of the spindle. For mounting to the inside of the free end of the spnidle, new TMD is proposed. The TMD is simply composed of a mass, a beam, and two spherical surface bearings, and it is possible to suppress whirl vibration of the spindle. The effectiveness of the TMD is confirmed by the experiment.

Measuring Forces on Immobilized Yeast Cells

The interaction of cells with biomedical sensors or sampling systems of bioreactors is one of the most crucial problems affecting the long-term stability of such devices. Cell adhesion on sensors can be influenced by the use of different sensor materials or material coatings [1]. The cell-materialinteraction can be characterized, e.g., by the adhesion force. Additionally, filter blocking on sampling devices for large scale bioreactors can be avoided under different hydrodynamic conditions. A new approach for small volume bioreactors consists in the application of high frequency electrical fields in connection with the utilization of microsytem components in sampling systems [2]. The physical background is the so called dielectrophoretic effect, which describes forces on non-conducting but polarizable particles caused by high frequency alternating fields in the range of a few kHz to some hundreds of MHz. This dynamic effect is also detectable on microorganisms. Forces are repulsive (negative dielectrophoresis) or attractive (positive dielectrophoresis) depending on frequency, conductivity, geometric conditions of the electrode structure, but also on the complex dielectric properties of the cells (or microorganisms) and the surrounding medium [3]. The action of the dielectrophoretic force can be visualised easily by light microscopy [2], but a direct measurement of the force itself is impossible by that method. Therefore, we used the Atomic Force Microscope (AFM) as a force sensor. A necessary step in such experiments is the immobilization of cells on an AFM cantilever [4]. In our study yeast cells were immobilized on the cantilever. In one application the adhesion force of the cells was measured on different materials. Another goal of this work was the characterization of the dielectrophoretic force on immobilized cells. But an immediate measurement of the dielectrophoretic force [5] is complicated by a superimposition with electrostatic forces [6]. Nevertheless, the measured force can be splitted because of different dependencies of both forces on the AC voltage and a DC offset. As a result, a qualitative detection of the dielectrophoretic force is shown for immobilized yeast cells. A suitable method was found to immobilize yeast cells on an AFM cantilever (fig. 1). Force-distance-curves had shown a very small adhesion force of the cantilever with cells to an optical glass of type Borofloat B33 and virtually no adhesion of a blank cantilever on B33. In comparison a gold coated glas was used as a test system. We found small interactions of a blank cantilever to the gold surface, but considerable interactions in the case of the cantilever with immobilized cells. Finally, there was a larger adhesion force on a phosphorylcholine coated glass (PC 1036) in comparison to B33. On this occasion nearly equal forces appeared for blank and treated cantilevers with slight differences depending on the used cantilever type. First results were obtained to characterize the dielectrophoretic force acting on immobilized yeast cells.

738 高強度鋼の長寿命疲労特性に及ぼす焼戻し温度の影響

In order to investigate the effect of tempering temperature on the fatigue properties of high strength steels and surface hardened steels in the super-long life range (N&ge;1×(10)^7), cantilever type rotating bending fatigue tests were carried out for SNCM439 specimens which tempered by the tempering temperature of four kind of 160℃, 300℃, 500℃ and 620℃. As a result of fatigue tests, all specimens tempered at 500℃ and 620℃ were "surface crack origin type". For the case of tempering temperature of 300℃, one specimen was "internal crack origin type" and other specimens were "surface crack origin type". For the case of tempering temperature of 300℃, 500℃ and 620℃, the tendency in which the S-N curves decreased again in the very long life regime over (10)^7 cycles could not be observed.

216 軸受け鋼の超高サイクル疲労特性と破壊過程の検討

In the study super-high cycle fatigue test in cantilever type rotating bending was conducted on SUJ2 bearing steels in air at room temperature. The fracture surfaces were analyzed to reconstruct the failure process by FRASTA technique for specimens by subsurface inner failure. It was found that fatigue crack was initiated at the inside of a fish-eye. At around the center of the fish-eye, inclusion or fine granular area was observed by the analysis.

C134 零位式放射温度計測システムの開発 : 測定原理の検証と MEMS 複合センサの試作

A novel radiation temperature measurement method was invented. In the traditional radiation thermometry, an emissivity data of a sample is necessary for converting the detected radiation intensity into temperature with a particular calibration curve. On the other hand, temperature of the sample can be decided by finding the sensor temperature at which the radiation intensity is null in our method. Introduction of the null method into radiation thermometry eliminates the need for the emissivity value. The principle of the method was verified with a measurement system where a heater-equipped commercial thermopile device was driven with a thermal feedback circuit. Quantitative temperature measurement was achieved for the flat brass surface with black paint or with plastic tape. Furthermore, a integrated radiation sensor having a cantilever type thermopile, electric heater and thermocouple was made by the silicon micro-fabrication technology. Measurement test with the sensor showed that the method absorbs the difference in emissivity, and that local temperature distribution in the sensor influences the detection of radiation intensity.