Diagonal Slits Research Articles

Ultrasonic complex vibration source using two longitudinal vibration transducers and a uniform rod with diagonal slits

It has been reported that ultrasonic welding using planar vibrations results in higher weld strength and less damage to the work pieces compared with ultrasonic welding using linear vibrations. However, torsional vibration transducers are small and expensive, thus reducing flexibility in the use of the vibration source. Therefore, in this study, we developed an ultrasonic longitudinal-torsional vibration source using longitudinal vibration transducers and a uniform rod with diagonal slits. The proposed vibration source generates torsional vibration by using a uniform rod with diagonal slits instead of a conventional torsional vibration transducer. As a result, it is found that a planar vibration locus is obtained by inputting two resonance frequencies simultaneously.

3Pa4-6 Development of complex vibration source using longitudinal vibration transducers and diagonal slits –Case of considering vibration of flange–

3Pa4-6 Development of complex vibration source using longitudinal vibration transducers and diagonal slits –Case of considering vibration of flange–

Reactive Impedance Surface (RIS) based asymmetric slit patch antenna loaded with complementary split ring resonator (CSRR) for circular polarization

ABSTRACTIn this paper a compact patch antenna backed with artificial meta-surface known as reactive impedance surface (RIS) is designed for circular polarization in the ISM band. The antenna consists of an asymmetric diagonal slits with pair of complementary split ring resonators (CSRRs) on patch over the RIS structure. Asymmetric slits and pair of CSRRs are inserted on radiating patch to achieve circular polarization. RIS is used for improving the radiation characteristics of the antenna, while RIS-based patch provides good impedance matching over a broad frequency range. Simulated results are in good agreement with the measured results.

Study on a longitudinal–torsional ultrasonic vibration system with diagonal slits

The longitudinal–torsional ultrasonic vibration machining process is popular for machining hard and brittle materials. A longitudinal–torsional ultrasonic vibration system with diagonal slits was designed for the ultrasonic vibration machining process based on the principle of acoustics propagation in this study. Four uniform diagonal slits were cut off on the horn cylinder to transform the longitudinal ultrasonic vibration into a longitudinal–torsional composite motion. A finite element analysis was used to optimize the mechanical structure of the vibration system. Dynamic characteristics of the vibration system were numerically studied, and the relationship of diagonal slits versus the resonance frequency and amplitudes of longitudinal–torsional vibration was analyzed, so that the longitudinal–torsional output amplitude can be optimized by rational choice of structure parameters of diagonal slits. Moreover, the movement locus of the system output end was obtained by utilizing the Origin software, which was proved to be elliptical, and the accuracy of the finite element model was confirmed by comparing numerically and experimentally determined resonant characteristics. In addition, the verification of longitudinal–torsional ultrasonic vibration was proved for the designed ultrasonic vibration system.

Ultrasonic metal welding by longitudinal-torsional vibration source consisting of two transducers

We study ultrasonic metal welding of dissimilar metals by using planar vibration locus. The planar vibration locus consists of the longitudinal vibration and the torsional vibration. In a previous study, we used an ultrasonic vibration source that contained a vibration converter comprising diagonal slits. The vibration source with diagonal slits was driven two frequencies in order to obtain a planar vibration locus. However, it was difficult to control individual vibration when using the vibration source with diagonal slits. In order to solve this problem, we have developed an ultrasonic longitudinal-torsional vibration source consisting of two transducers in which the longitudinal-torsional vibration can be controlled. The developed vibration source is consists of a longitudinal transducer and a torsional transducer attached to the both ends of a stepped horn with the length of two wavelength of the propagating vibration. This vibration source can generate planar vibration locus of substantially square. In this study, ultrasonic metal welding of dissimilar metals was studied by using the vibration source consisting of two transducers. As a result, high weld strength was obtained in the case of welding of the planar locus than welding of only longitudinal or torsional vibration loci.

Longitudinal–torsional vibration source consisting of two transducers with different vibration modes

The planar vibration locus is applicable to, for example, ultrasonic welding, ultrasonic machining, and ultrasonic polishing. In a previous study, we obtained the planar locus using an ultrasonic longitudinal–torsional vibration source that contained a vibration converter comprising diagonal slits to drive two frequencies. It was difficult to obtain only longitudinal or torsional vibration when using an ultrasonic complex vibration source with diagonal slits. Therefore, the versatility of the ultrasonic complex vibration source with diagonal slits was low. We have developed an ultrasonic longitudinal–torsional vibration source in which the longitudinal–torsional vibration can be controlled. The requirements for an ultrasonic vibration source were longitudinal–torsional vibration control and that the source has a planar locus. In this paper, we investigate a new type of vibration source that satisfies these requirements. It consists of two transducers, a longitudinal transducer and a torsional transducer, attached to the ends of a uniform rod with a length of one wavelength of the propagating vibration.

Reducing the Complexity: Enantioselective Chiral Near-Fields by Diagonal Slit and Mirror Configuration

We report an easy-to-fabricate plasmonic design consisting of diagonal slits in a metallic film on top of a mirror for the generation of chiral near-fields of one single handedness. Our numerical investigations show that the distance between the two layers is crucial for the properties of this design. While the far-field response can be used to identify layer distances with strong chiral near-fields, this distance must be small enough to additionally ensure single-handedness of the respective fields close to the slit area. The fields of interest can be easily accessed by chiral molecules because they are located within the slits. Based on this finding, we propose and numerically verify a novel technique for chiroptical spectroscopy in a reflection geometry.

Numerical Design of Stepped Compound Horn with Longitudinal-Torsional Vibration under Single Acoustic Excitation

The mechanism of longitudinal-torsional vibration (LTV) realized by using converter with multiple diagonal slits (MDS) was analyzed based on the acoustic wave propagation when acoustic wave enters obliquely from steel to air. The influences of geometrical parameters of the stepped compound horn with multiple diagonal slits on natural frequencies of LTV were studied with finite element analysis (FEA). The design procedure of stepped compound horn with LTV was provided. The vibration characteristics of actual horn were analyzed with simulation and test. The FEA results show that LTV of the output end of the stepped compound horn may be realized when the input end is excited by longitudinal vibration at certain natural frequency if suitable geometrical dimensions are selected, and the amplitude of the horn is periodical; the trajectory of the particle in the output end is helical curve. The test results indicate that LTV may be realized by stepped compound horn under single acoustic excitation, and the vibration frequency is close to the simulation result, and its vibration properties are good. This method may be applied to design the acoustics system of ultrasonic machining with LTV under single acoustic excitation.

Characteristics of ultrasonic complex vibration for hole machining in brittle materials: Comparison of longitudinal and complex vibration sources

Ceramic materials have the advantage of abrasion resistance, heat resistance, and corrosion resistance compared with metal materials. The combination of ultrasonic vibration and polishing slurry has been shown to be an effective method for machining holes in brittle materials. However, conventional ultrasonic methods use only longitudinal vibration. Complex vibration sources with diagonal slits have been applied to ultrasonic motors and ultrasonic welding; in contrast, few studies have been conducted on ultrasonic machining using complex vibration and polishing slurry. Removal rates and machining accuracy are expected to be improved by using ultrasonic complex (longitudinal-torsional) vibration. Therefore, we have developed a new method using polishing slurry together with ultrasonic longitudinal and torsional vibration sources with diagonal slits for hole machining of brittle materials. Torsional vibration is considered to improve the processing of the hole side of ceramic materials such that the polishing slurry can circulate more easily. We assume improvement of removal rate and machining accuracy for that reason. In experiments, soda-lime glass is used as the processing material in ultrasonic complex vibration or ultrasonic longitudinal vibration, and machining time is measured to assess the hole machining characteristics.

Design of Longitudinal-Torsional Vibration Stepped Horn with Multiple Diagonal Slits

Based on the theory of acoustic propagation, the realization mechanism of longitudinal-torsional vibration (LTV) by converter of cylinder with multiple diagonal slits (MDS) under single excitation was studied. The influences of composite stepped horns structural parameters on resonant frequency were studied by numerical analysis method, and the horn (resonant frequency about 20kHz) with LTV was designed. The results show that LTV could be realized under single excitation of longitudinal vibration when resonant frequency is 20498Hz, and the amplitude varied periodically. The results can be applied in the design of acoustic system in ultrasonic machining with LTV.

Coupling and degenerating modes in longitudinal–torsional step horns

Longitudinal–torsional vibration is used and proposed for a variety of ultrasonic applications including motors, welding, and rock-cutting. To obtain this behavior in an ultrasonic step horn one can either, (i) couple the longitudinal and torsional modes of the horn by incorporating a ring of diagonal slits in the thick base section or, (ii) place helical flutes in the thin stem section to degenerate the longitudinal mode into a modified behavior with a longitudinal–torsional motion. This paper compares the efficacy of these two design approaches using both numerical and experimental techniques.

A Strategy for Delivering High Torsionality in Longitudinal-Torsional Ultrasonic Devices

A composite longitudinal-torsional vibration mode has applications in ultrasonic motors, ultrasonic welding and ultrasonic drilling. There are two ways to obtain this vibration behaviour using a single transducer, namely (i) coupling of a longitudinal and a torsional mode, which is known to be difficult; and (ii) degenerating a longitudinal mode to deliver longitudinal-torsional behaviour at the horn tip. A mode-degenerating horn is achieved by incorporating helical or diagonal slits in an otherwise traditional exponential horn driven by a Langevin transducer. However, it is often difficult with this configuration to avoid coupling of unwanted bending modes, low responsiveness, and loss of ultrasonic energy due to boundaries between tuned components. Therefore, in this study the mode-degenerating characteristics are achieved by incorporating the helical slits and exponential geometry features in the front mass of the transducer itself. Finite element analysis and vibration experimental analysis show that this strategy prevents coupling of bending modes, increases responsiveness, and reduces energy losses. Most importantly the transducer delivers a very high torsionality.

Vibrator Development for Hole Machining by Ultrasonic Longitudinal and Torsional Vibration

We are developing a new method using ultrasonic longitudinal and torsional vibrations of a hollow-type stepped horn with diagonal slits for hole machining. We foresee that, with this method, equipment can be simplified and miniaturized. In this study, ultrasonic vibration sources of a horn with diagonal slits and a uniform rod with diagonal slits are used. The longitudinal and torsional vibration characteristics of the horn are studied and the shape of the diagonal slits is examined. As a result, to obtain the maximum torsional vibration at the tip, the diagonal slit conditions were as follows: the center position of the diagonal slits was the position of the node of longitudinal vibration, the angle was 35°, and the depth was 3.5 mm in all cases of cross-sectional ratio. It was clarified that a horn with diagonal slits can be used for hole machining of brittle materials.

Development of Cylinder with Multiple Diagonal Slits for Ultrasonic Longitudinal - Torsional Vibration Turn-Milling

Cylinder with multiple diagonal slits is one of the core parts of longitudinal-torsional resonance ultrasonic device. Its structure was more complex, the traditional processing processed it very difficult, and the traditional analytical methods were also difficult to make accurate description to system. The paper researched cylinder with multiple diagonal slits using experimental method, analysis of electrical discharge machining forming tools of the slits and three-dimensional modeling; developed cylinder with multiple diagonal slits, analyzed longitudinal-torsional resonance and mechanical properties of cylinder with multiple diagonal slits using finite element analysis method. Tested resonant frequency of cylinder with multiple diagonal slits with precision impedance analyzer. The finite element analysis results compared with tested results, and analysis of error between them, finite element analysis results slightly lower than the test results but the error was within the allowed range. Comparison of results and analysis of error indicated that developed cylinder with multiple diagonal slits meet requirement.

Two new ascomycetes from rainforest litter in Costa Rica

Two new ascomycetes, Boerlagiomyces costaricensis (Pleosporales) and Scopinella musciformis (Sordariales sensu lato), from litter samples collected in rainforests of Costa Rica, are described and illustrated. Boerlagiomyces costaricensis has globose, ostiolate ascomata covered by numerous setae-like hairs; cylindrical, fissitunicate asci without apical structures; and large, fusiform, muriform, hyaline to pale brown ascospores. Scopinella musciformis is characterized by ostiolate ascomata with a few compact clusters of hypha-like hairs distributed on the peridial surface and a long neck; ovate to ellipsoidal unitunicate asci; and small quadrangular ascospores with diagonal germ slits.

Two new ascomycetes from rainforest litter in Costa Rica

Two new ascomycetes, Boerlagiomyces costaricensis (Pleosporales) and Scopinella musciformis (Sordariales sensu lato), from litter samples collected in rainforests of Costa Rica, are described and illustrated. Boerlagiomyces costaricensis has globose, ostiolate ascomata covered by numerous setae-like hairs; cylindrical, fissitunicate asci without apical structures; and large, fusiform, muriform, hyaline to pale brown ascospores. Scopinella musciformis is characterized by ostiolate ascomata with a few compact clusters of hypha-like hairs distributed on the peridial surface and a long neck; ovate to ellipsoidal unitunicate asci; and small quadrangular ascospores with diagonal germ slits.

Configurations of high-frequency ultrasonics complex vibration systems for packaging in microelectronics

Ultrasonic high-frequency complex vibrations are effective for various ultrasonic high-power applications. Three types of ultrasonic complex vibration system with a welding tip vibrating elliptical to circular locus for packaging in microelectronics were studied. The complex vibration sources are using (1) a longitudinal–torsional vibration converter with diagonal slits that is driven only by a longitudinal vibration source, (2) a complex transverse vibration rod with several stepped parts that is driven by two longitudinal vibration source crossed at a right angle and (3) a longitudinal vibration circular disk and three longitudinal transducers that are installed at the circumference of the disk.

Ultrasonic motor using a one-dimensional longitudinal-torsional vibration converter with diagonal slits

Characteristics of ultrasonic rotary motors using a longitudinal-torsional vibration converter 15 mm to 50 mm in diameter are described. To obtain large torque, ultrasonic motors using one-dimensional longitudinal-torsional converters with diagonal slits are proposed. The converters have rather simple and tough structures and are driven using only a longitudinal vibration transducer. The vibration converters are made of metal materials and have diagonal slits cut along the converter circumference adjacent to a nodal position of longitudinal vibration. The ultrasonic motors consist of a vibration converter with a driving part at its free edge, and a rotor part pressed statically to a driving surface using corned disk springs. Vibration characteristics and vibration loci at driving surfaces of these motors are measured under loaded and nonloaded conditions and under forward and reverse rotating conditions. Maximum torques over 0.3 to 23 N m were obtained by the converters 15 to 50 mm in diameter and at frequencies of 80 to 23 kHz. Maximum revolution obtained was over 550 rpm using a 15 mm diameter motor of 56 kHz.

Load Characteristics and Vibration Loci at the Driving Surfaces of Ultrasonic Rotary Motor using a Longitudinal-Torsional Vibration Converter

Characteristics of ultrasonic rotary motors using a longitudinal-torsional vibration converter, 15 to 50 mm in diameter, are studied. To obtain a large torque, ultrasonic motors using one-dimensional longitudinal-torsional converters with diagonal slits are proposed. The converters have simple and tough structures and are driven using only a longitudinal vibration transducer. The vibration converters are fabricated from metal materials and have diagonal slits cut along the converter circumference, adjacent to a nodal position of longitudinal vibration. The ultrasonic motors consist of a vibration converter having a driving part at its free edge, and a rotor part statically pressed to the driving surface using corned disk springs. The vibration characteristics and vibration loci at the driving surfaces of these converters and motors are measured under loaded and nonloaded conditions and at forward and reverse rotating conditions, using two laser Doppler vibrometers. Vibration locus shapes are changed according to the load conditions and frequencies. Maximum torques of over 0.2 N·m are obtained by the converters, 15 to 20 mm in diameter, and at frequencies of 56 to 65 kHz. The maximum revolution speed obtained is over 550 r.p.m. using a 15-mm-diameter motor of 56 kHz.

Load characteristics of ultrasonic rotary motor using a longitudinal-torsional vibration converter with diagonal slits. Large torque ultrasonic rotary motor

The characteristics of an ultrasonic rotary motor using a longitudinal-torsional vibration converter with a large torque are studied. To obtain a large torque, ultrasonic motors using a slitted longitudinal-torsional vibration converter are proposed. The converters have rather simple structures and are driven using only a longitudinal vibration transducer. The vibration converters have 8 to 16 diagonal slits of 45 ° and 0.5 to 1.0 mm width. The designed ultrasonic motors consist of a vibration converter with a driving part at its free edge, and a rotor part pressed statically to a driving surface using corned disk springs. Characteristics of these motors are measured under loading by various weights. Maximum torques over 0.3 to 23 Nm were obtained by converters of 15 to 60 mm in diameter and of 56 to 23 kHz in frequency. Maximum revolution obtained was over 290 r.p.m. using a 15 mm diameter motor of 56 kHz.