Determination of the Resonance Frequency and Spring Constant of FluidFM Cantilevers with Numerical Simulations

Determination of Notched Input for Equipment Under Random Vibrations

10.20855/ijav.2021.26.41814 ◽

2021 ◽

Vol 26 (4) ◽

pp. 316-324

Author(s):

K. Renji

Keyword(s):

Resonance Frequency ◽

Numerical Simulations ◽

Random Vibration ◽

Natural Frequencies ◽

Vibration Testing ◽

Random Vibrations ◽

Random Loads ◽

Vibration Tests ◽

Very High

Equipment that is mounted on a spacecraft is subjected to random vibration tests to verify whether they can withstand the specified random loads. These tests are generally carried out by using shaker systems during which equipment experiences very high responses at the natural frequencies of the equipment. To reduce such over-testing, notching of the input is done. Notching of the input is normally carried out by considering the force generated at the base and limiting it to a specified value. To accomplish the notching, the force spectrum to be limited and measurement of base force during the tests are needed. This work shows that the acceleration input at the interface of equipment gets reduced at its resonance frequency and this feature can be utilized in arriving at the notched input. An expression to determine the depth of notching is derived and the results are compared with those obtained using numerical simulations. The depth of the notch increases with the response of the oscillator and it is sensitive to the stiffness ratios rather than the mass ratios of the oscillator and the mounting panel. This behavior and the expressions derived can be effectively used in arriving at the notched input for an equipment without the need for measuring the base force, especially for random vibration testing, which is demonstrated with an example.

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Natural stone test methods. Determination of the dynamic elastic modulus of elasticity (by measuring the fundamental resonance frequency)

10.3403/03027526 ◽

2004 ◽

Cited By ~ 3

Keyword(s):

Elastic Modulus ◽

Resonance Frequency ◽

Modulus Of Elasticity ◽

Test Methods ◽

Natural Stone ◽

Dynamic Elastic Modulus ◽

Fundamental Resonance ◽

Fundamental Resonance Frequency

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Does the manual insertion torque of smartpegs affect the outcome of implant stability quotients (ISQ) during resonance frequency analysis (RFA)?

International Journal of Implant Dentistry ◽

10.1186/s40729-019-0195-1 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Ingrid Kästel ◽

Giles de Quincey ◽

Jörg Neugebauer ◽

Robert Sader ◽

Peter Gehrke

Keyword(s):

Resonance Frequency ◽

Frequency Analysis ◽

Insertion Torque ◽

Resonance Frequency Analysis ◽

Implant Stability ◽

Reliable Determination ◽

Torque Values ◽

Finger Pressure

Abstract Background There is disagreement about the optimal torque for tightening smartpegs for resonance frequency analysis (RFA). Subjective finger pressure during hand tightening could affect the reliability of the resulting values. The aim of the current study was therefore to assess whether or not the insertion torque of a smartpeg magnetic device influences the implant stability quotient (ISQ) value during RFA. Methods Thirty self-tapping screw implants (XiVE S, Dentsply Sirona Implants, Bensheim, Germany) with a diameter of 3.8 mm and a length of 11 mm were inserted in three cow ribs with a bone quality of D1. The RFA value of each implant was measured (Ostell, FA W&H Dentalwerk, Bürmoos, Austria) in two orthogonal directions (mesial and buccal) after tightening the corresponding smartpeg type 45 with a mechanically defined value of 5 Ncm (Meg Torq device, Megagen, Daegu, South Korea) (test). Additionally, 4 different examiners measured the RFA after hand tightening the smartpegs, and the results were compared (control). Insertion torque values were determined by measuring the unscrew torque of hand seated smartpegs (Tohnichi Manufacturing Co. Ltd, Tokyo, Japan). Results The ISQ values varied from 2 to 11 Ncm by hand tightening and from 2 to 6 Ncm by machine tightening. The comparison of hand and machine tightening of smartpegs displayed only minor differences in the mean ISQ values with low standard deviations (mesial 79.76 ± 2,11, buccal 77.98 ± 2,) and no statistical difference (mesial p = 0,343 and buccal p = 0,890). Conclusions Manual tightening of smartpeg transducers allows for an objective and reliable determination of ISQ values during RFA.

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