Effect Of Static Force Research Articles

Dynamic Simulation of High-Pile Wharf Slab under Action of Irregular Waves

The dynamic responses of single wharf slab and whole high-pile wharf structure is studied in modal analysis by 3D finite element model using software ABAQUS. According to the static force calculation module and the transient dynamics module of the ABAQUS finite element calculation, the displacement of wharf slab central point is calculated according to the effects of static force, slow variation, and the uplift pressure from both the shock and composite wave. Then the effects of wave force frequency impacting on the structure dynamic response is researched by the different high-frequency waves. These analysis results provide scientific basis and technical guidance for the high-pile wharf dynamic research in port engineering.

The effect of static force on round window stimulation with the direct acoustic cochlea stimulator

The Direct Acoustic Cochlea Stimulator Partial Implant (DACS PI, Phonak Acoustic Implants SA, Switzerland) is intended to stimulate the cochlea by a conventional stapedotomy piston that is crimped onto the DACS PI artificial incus. An alternative approach to the round window (RW) is successfully done with other devices, having the advantage of being also independent of the existence of middle ear structure (e.g. ossicles). Here the possibility of stimulating the RW with the DACS actuator is investigated including the impact of static force on sound transmission to the cochlea.The maximum equivalent sound pressure output with RW stimulation was determined experimentally in fresh human temporal bones. Experiments were performed in analogy to the ASTM standard (F2504.24930-1) method for the output determination of implantable middle ear hearing devices (IMEHDs) in human cadaveric temporal bones (TBs). ASTM compliant temporal bones were stimulated with a prosthesis having a spherical tip (∅0.5 mm) attached to the actuator. The stimulation was performed perpendicular to the round window membrane (RWM) at varying position relative to the RW and the resulting static force on the RW membrane was determined.At each position the displacement output of the DACS PI actuator and the stapes footplate (SFP) vibration in response to actuator stimulation was measured with a Laser Doppler Velocimeter (LDV). By comparison of the achieved output at the stapes footplate in response to sound and transducer stimulation the equivalent sound pressure level at the tympanic membrane at 1Vrms input voltage was calculated assuming that the SFP displacement in both conditions is a measure of perceived loudness, as it is done in the ASTM standard.Ten TB preparations within the acceptance range of the ASTM standard were used for analysis. The actuator driven stapes footplate displacement amplitude as well as the resulting equivalent sound pressure level was highly dependent on the static force applied to the RW. The sound transfer efficiency from the RW to the stapes footplate increased monotonically with increasing static load. At a moderate static force load (approx. 3.9 mN) the obtained average sound equivalent sound pressure level was 102–120 eq. dB SPL @ nominally 1Vrms input for frequencies ≤4 kHz. At higher frequencies (6–10 kHz) the achieved output dropped to ∼90 dB SPL.This output was obtained at loading conditions compatible with the actuator safe operating range, although it was possible to increase the output further by increasing the static force load.Our results demonstrate for a first time that static force applied to the RW is crucial for sound transmission efficiency. Further we could show that RW stimulation with the DACS PI actuator is possible having a maximum output that is sufficient to treat moderate and pronounced sensorineural hearing losses (SNHL).This article is part of a Special Issue entitled “MEMRO 2012”.

A Comparative Study on Ultrasonic Machining of Red Granite

Ultrasonic machining has been proven to be a promising machining method on hard and brittle materials. However, due to the absence of high power ultrasonic machine tools, reported studies on ultrasonic machining were mainly concerned of relatively small hole drilling of the given materials. In the present work, with the development of the higher power Rotary Ultrasonic Machine Tool, two kinds of ultrasonic face machining with free abrasives, namely, Non-rotating Ultrasonic Machining with Free Abrasives (NRUSM) and Rotary Ultrasonic Machining with Free Abrasives (RUSM) are designed and comparatively conducted for the red granite, which is a typical hard-to-machine natural material. The effects of static force, spindle speed and amplitude of ultrasonic vibration on the performance of the machining are evaluated in terms of the material removal rate and surface quality. Experimental results indicate that ultrasonic machining is effective for face milling of the stone material with the designed machine tool. Furthermore, machining performances in RUSM are superior to those in NRUSM.

Effect of static force on bone conduction hearing thresholds and comfort

Objective: To assess the effect of the static force of a bone vibrator on the results of bone conduction (BC) threshold measurements and comfort. Design: BC thresholds were determined for 40 participants using the standardized P-3333 headband and a leather adjustable headstrap with variable static forces (2.4, 3.4, 4.4, 5.4 N). Comfort ratings were examined using a five-point Likert scale. Results: Mean BC thresholds were within ± 2 dB across all conditions; differences may be considered small enough to be clinically insignificant. Participants experienced significantly greater discomfort with the P-3333 versus the adjustable headstrap. The mean static force of the P-3333 varied considerably and was higher in situ than the calibration standard of 5.4 N. Conclusions: The results suggest that future revisions of relevant international and national standards should address the use of an adjustable headstrap and a static force less than 5.4 N.SumarioObjetivo: Evaluar el efecto de la fuerza estática de un vibrador óseo en los resultados de las mediciones de los umbrales por conducción ósea (BC) y sobre la comodidad. Diseño: Se determinaron los umbrales BC en 40 participantes utilizando la diadema estandarizada P-3333 y una banda cefálica ajustable con fuerzas estáticas variables (2.4, 3.4, 4.4, 5.4 N). La calificación de la comodidad se examinó con una escala Likert de cinco puntos. Resultados: Los umbrales promedio estuvieron en los ± 2dB a través de todas las condiciones; las diferencias pueden ser consideradas lo suficientemente pequeñas para ser clínicamente insignificantes. Los participantes experimentaron una molestia mucho mayor con la P-3333 que con la banda cefálica ajustable. La fuerza estática de la P-3333 varió considerablemente y fue mayor in situ que en el estándar de calibración de 5.4 N. Conclusiones: Los resultados sugieren que las revisiones de los estándares internacionales y nacionales deben dirigir la atención al uso de las bandas cefálicas ajustables y una fuerza estática menor que 5.4 N.

Experimental Investigation on Ultrasonic Face Machining of Glass with Free Abrasives

Serials of ultrasonic face machining experiments were designed and carried out on glass materials with free abrasives. Two different kinds of ultrasonic machining, namely, non-rotary ultrasonic machining (NRUSM) with free abrasives and rotary ultrasonic machining (RUSM) with free abrasives were compared. Two systems were set up to in-process monitor the changes of static forces and frequency respectively. The effects of static force, spindle speed and amplitude of ultrasonic vibration on material removal rate (MRR) and surface roughness were analyzed. The surface of workpieces was also observed by a digital video microscope system. The experimental results indicated that, at the given conditions, there exists an optimal value of static force and amplitude of vibration to obtain the maximum MRR, and RUSM was found to be superior to NRUSM in the MRR, but inversely in surface roughness.

Dynamic stability of radially stiffened annular plates

The dynamic stability of radially stiffened annular plates with both edges subjected to in-plane forces is studied. For this purpose a sector and a beam finite element is used. The method is applied to annular plates with several stiffeners of uniform rectangular cross-section located at equal angular intervals. The instability regions are determined for a wide range of exciting frequencies with different boundary conditions using Bolotin's method by varying the number and size of the stiffeners. Also the effect of static forces are taken into account.

Static and dynamic stability of variable thickness annular plates

The static and dynamic stability of variable thickness annular plates subject to periodic in-plane forces is studied. For this purpose a sector finite element model with the wave propagation technique of cyclic symmetry is developed. Plate thickness is both increased and decreased in the outward radial direction by the equations h = h max( r r o ) +λ or h = h max( r r i ) −λ respectively. The Mindlin plate finite element model is used to handle both the thick and thin plates. The instability regions are determined for a wide range of excitation frequencies with different boundary conditions by using Bolotin's method with the effect of static forces taken into account.

Measurement of Specific Mechanical Impedance of the Skin: Effects of Static Force, Site of Stimulation, Area of Probe, and Presence of a Surround

This study attempted to investigate the mechanical response of skin-tissue systems under conditions commonly employed in psychophysical investigations of the tactile system. The influence of these conditions on the specific mechanical impedance was determined and evidence was found suggesting that if one desires to avoid altering the mechanical characteristics, then the parameters to be controlled are the pressure exerted by the probe and the area of the probe. The presence of a surround also influenced the mechanical characteristics when the site of stimulation was the volar forearm, but not when it was the finger or the thenar eminence.