Dynamics of Cricket Sound Production

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Vamsy Godthi ◽  
Rudra Pratap
Keyword(s):  
Natural Frequency ◽  
Sound Production ◽  
Microelectromechanical Systems ◽  
Beat Frequency ◽  
Impulsive Loading ◽  
Frequency Multiplier ◽  
Fe Model ◽  
Song Frequency ◽  
Cricket Song ◽  
Impulse Train

The clever designs of natural transducers are a great source of inspiration for man-made systems. At small length scales, there are many transducers in nature that we are now beginning to understand and learn from. Here, we present an example of such a transducer that is used by field crickets to produce their characteristic song. This transducer uses two distinct components—a file of discrete teeth and a plectrum that engages intermittently to produce a series of impulses forming the loading, and an approximately triangular membrane, called the harp, that acts as a resonator and vibrates in response to the impulse-train loading. The file-and-plectrum act as a frequency multiplier taking the low wing beat frequency as the input and converting it into an impulse-train of sufficiently high frequency close to the resonant frequency of the harp. The forced vibration response results in beats producing the characteristic sound of the cricket song. With careful measurements of the harp geometry and experimental measurements of its mechanical properties (Young's modulus determined from nanoindentation tests), we construct a finite element (FE) model of the harp and carry out modal analysis to determine its natural frequency. We fine tune the model with appropriate elastic boundary conditions to match the natural frequency of the harp of a particular species—Gryllus bimaculatus. We model impulsive loading based on a loading scheme reported in literature and predict the transient response of the harp. We show that the harp indeed produces beats and its frequency content matches closely that of the recorded song. Subsequently, we use our FE model to show that the natural design is quite robust to perturbations in the file. The characteristic song frequency produced is unaffected by variations in the spacing of file-teeth and even by larger gaps. Based on the understanding of how this natural transducer works, one can design and fabricate efficient microscale acoustic devices such as microelectromechanical systems (MEMS) loudspeakers.

scholarly journals Resonators in insect sound production: how insects produce loud pure-tone songs

1999 ◽  
Vol 202 (23) ◽  
pp. 3347-3357 ◽  
Author(s):  
H.C. Bennet-Clark
Keyword(s):  
Pure Tone ◽  
Sound Production ◽  
Slow Muscle ◽  
Frequency Multiplier ◽  
Contraction Rate ◽  
Mechanical Resonator ◽  
Second Stage ◽  
Different Types ◽  
Song Frequency ◽  
Slow Contraction

In a resonant vibration, two reactive elements, such as a mass and a spring, interact: the resonant frequency depends on the magnitude of these two elements. The build-up and decay of the vibration depend on the way the resonator is driven and on the damping in the system. The evidence for the existence of resonators in insect sound production is assessed. The mechanics of different types of sound-producing system found in insects is described. Mechanical frequency-multiplier mechanisms, which convert the relatively slow contraction of muscles to the higher frequency of the sound, are commonly used to convert the comparatively slow muscle contraction rate to the higher frequency of the sound. The phasing and rate of mechanical excitation may also affect the frequency and duration of the sound that is produced. Although in many insects the song may appear to be produced by the excitation of a simple resonator, the song frequency may not be constant, suggesting that other factors, such as the mechanism of excitation, or variation of the effective mass or elasticity of the system during sound production, may be additional determinants of the song frequency. Loud, and hence efficient, transduction of the energy of a mechanical resonator into sound may involve a second stage of transduction which, by damping the resonator, may compromise tonal purity. Some insect singers resolve this problem by tuning both stages of transduction to the same frequency, thereby maintaining tonal purity.

Acoustics of Sound Production and of Hearing in the Bladder Cicada Cystosoma Saundersii (Westwood)

1978 ◽  
Vol 72 (1) ◽  
pp. 43-55 ◽  
Author(s):  
N.H. FLETCHER ◽  
K. G. HILL
Keyword(s):  
Sound Production ◽  
Abdominal Cavity ◽  
Low Frequency ◽  
Sound Intensity ◽  
Electrical Network ◽  
Directional Hearing ◽  
Hearing Sensitivity ◽  
Physical Mechanisms ◽  
Radiated Sound ◽  
Song Frequency

The male cicada of the species Cystosoma saundersii has a grossly enlarged, hollow abdomen and emits a loud calling song with a fundamental frequency of about 800 Hz. At the song frequency, its hearing is nondirectional. The female of C. saundersii lacks sound producing organs, has no enlargement of the abdomen, but possesses an abdominal air sac and has well developed directional hearing at the frequency of the species' song. Physical mechanisms are proposed that explain these observations in semi-quantitative detail using the standard method of electrical network analogues. The abdomen in the male, with its enclosed air, is found to act as a system resonant at the song frequency, thus contributing a large gain in radiated sound intensity. Coupling between this resonator and the auditory tympana accounts for the observed hearing sensitivity in the male, but destroys directionality. In the female, the abdominal cavity acts in association with the two auditory tympana as part of a phase shift network which results in appreciable directionality of hearing at the unusually low frequency of the male song.

scholarly journals Constrained Tibial Vibration in Mice: A Method for Studying the Effects of Vibrational Loading of Bone

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Blaine A. Christiansen ◽  
Philip V. Bayly ◽  
Matthew J. Silva
Keyword(s):  
Soft Tissue ◽  
Frequency Response ◽  
Natural Frequency ◽  
Lower Leg ◽  
Bone Strain ◽  
Fe Model ◽  
Loading Method ◽  
Vibrational Loading ◽  
Controlled Conditions

Vibrational loading can stimulate the formation of new trabecular bone or maintain bone mass. Studies investigating vibrational loading have often used whole-body vibration (WBV) as their loading method. However, WBV has limitations in small animal studies because transmissibility of vibration is dependent on posture. In this study, we propose constrained tibial vibration (CTV) as an experimental method for vibrational loading of mice under controlled conditions. In CTV, the lower leg of an anesthetized mouse is subjected to vertical vibrational loading while supporting a mass. The setup approximates a one degree-of-freedom vibrational system. Accelerometers were used to measure transmissibility of vibration through the lower leg in CTV at frequencies from 20Hzto150Hz. First, the frequency response of transmissibility was quantified in vivo, and dissections were performed to remove one component of the mouse leg (the knee joint, foot, or soft tissue) to investigate the contribution of each component to the frequency response of the intact leg. Next, a finite element (FE) model of a mouse tibia-fibula was used to estimate the deformation of the bone during CTV. Finally, strain gages were used to determine the dependence of bone strain on loading frequency. The in vivo mouse leg in the CTV system had a resonant frequency of 60Hz for ±0.5G vibration (1.0G peak to peak). Removing the foot caused the natural frequency of the system to shift from 60Hzto70Hz, removing the soft tissue caused no change in natural frequency, and removing the knee changed the natural frequency from 60Hzto90Hz. By using the FE model, maximum tensile and compressive strains during CTV were estimated to be on the cranial-medial and caudolateral surfaces of the tibia, respectively, and the peak transmissibility and peak cortical strain occurred at the same frequency. Strain gage data confirmed the relationship between peak transmissibility and peak bone strain indicated by the FE model, and showed that the maximum cyclic tibial strain during CTV of the intact leg was 330±82με and occurred at 60–70Hz. This study presents a comprehensive mechanical analysis of CTV, a loading method for studying vibrational loading under controlled conditions. This model will be used in future in vivo studies and will potentially become an important tool for understanding the response of bone to vibrational loading.

Reduced Order Model Analysis of Frequency Response of Alternating Current Near Half Natural Frequency Electrostatically Actuated MEMS Cantilevers

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Israel Martinez ◽  
Martin W. Knecht
Keyword(s):  
Natural Frequency ◽  
Microelectromechanical Systems ◽  
Multiple Scales ◽  
Alternating Current ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order ◽  
Electrostatically Actuated ◽  
Mems Resonator ◽  
Fringe Effect

This paper uses the reduced order model (ROM) method to investigate the nonlinear-parametric dynamics of electrostatically actuated microelectromechanical systems (MEMS) cantilever resonators under soft alternating current (AC) voltage of frequency near half natural frequency. This voltage is between the resonator and a ground plate and provides the actuation for the resonator. Fringe effect and damping forces are included. The resonator is modeled as a Euler-Bernoulli cantilever. ROM convergence shows that the five terms model accurately predicts the steady states of the resonator for both small and large amplitudes and the pull-in phenomenon either when frequency is swept up or down. It is found that the MEMS resonator loses stability and undergoes a pull-in phenomenon (1) for amplitudes about 0.5 of the gap and a frequency less than half natural frequency, as the frequency is swept up, and (2) for amplitudes of about 0.87 of the gap and a frequency about half natural frequency, as the frequency is swept down. It also found that there are initial amplitudes and frequencies lower than half natural frequency for which pull-in can occur if the initial amplitude is large enough. Increasing the damping narrows the escape band until no pull-in phenomenon can occur, only large amplitudes of about 0.85 of the gap being reached. If the damping continues to increase the peak amplitude decreases and the resonator experiences a linear dynamics like behavior. Increasing the voltage enlarges the escape band by shifting the sweep up bifurcation frequency to lower values; the amplitudes of losing stability are not affected. Fringe effect affects significantly the behavior of the MEMS resonator. As the cantilever becomes narrower the fringe effect increases. This slightly enlarges the escape band and increases the sweep up bifurcation amplitude. The method of multiple scales (MMS) fails to accurately predict the behavior of the MEMS resonator for any amplitude greater than 0.45 of the gap. Yet, for amplitudes less than 0.45 of the gap MMS predictions match perfectly ROM predictions.

Nonlinear free vibrations analysis of overhung rotors under the influence of gravity

2019 ◽  
Vol 234 (2) ◽  
pp. 575-588
Author(s):  
M Moradi Tiaki ◽  
SAA Hosseini ◽  
H Shaban Ali Nezhad
Keyword(s):  
Natural Frequency ◽  
High Frequency ◽  
Multiple Scales ◽  
Perturbation Technique ◽  
Equations Of Motion ◽  
Beat Frequency ◽  
Dynamical Behavior ◽  
Free Vibrations ◽  
Beam Model ◽  
Rayleigh Beam

In this paper, nonlinear free vibration of a cantilever flexible shaft carrying a rigid disk at its free end (overhung rotor) is investigated. The Rayleigh beam model is used and the rotor has large amplitude vibrations. With the assumption of inextensibility, the effect of nonlinear curvature and inertia is considered. The effect of disk mass on the dynamical behavior of the system is studied in the presence and absence of gravity (horizontal and vertical rotors). By using perturbation technique (method of multiple scales), the main focus is on the influence of gravity on equations of motion and on quantities such as amplitude and damped natural frequency. Here, a different behavior is observed due to the rotor weight. Indeed, the combination effects of gyroscopic term, nonlinearity and gravity are studied on the modal behavior of the system. It is shown that the static deflection creates second order nonlinear terms and changes the nonlinear damped natural frequency. With considering of gravity, both beat and high frequency in beat phenomenon increase. With increasing of the rotor weight, the minimum value of amplitude is extremely amplified in the direction of gravity but in the other transverse direction, amplitude of vibrations decreases. In addition, it is found that the weight has directly influence on beat frequency, while the mass ratio between disk and beam affects the high frequency.

scholarly journals Dynamic Characteristics Analysis of the Six-Axis Force/Torque Sensor

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Liyue Fu ◽  
Aiguo Song
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Dynamic Models ◽  
Dynamic Range ◽  
Model Identification ◽  
Step Response ◽  
Fe Model ◽  
De Algorithm ◽  
Characteristics Analysis ◽  
Experimental Values

In this study, dynamic characteristics of a robot six-axis wrist force/torque (F/T) sensor with crossbeam elastomer are analyzed by two methods of model identification, a method for simultaneous identification of order and parameters of the model (SIM) and a method based on the differential evolution (DE) algorithm. Firstly, by establishing the simplified mechanical model and finite element (FE) model, respectively, natural frequency of the six-axis wrist F/T sensor is calculated. Secondly, dynamic calibration experiment is conducted. Lastly, two dynamic models of the sensor are identified by SIM and DE methods and the dynamic characteristics of the sensor, such as natural frequency and working band, are further analyzed. Comparing experimental values with the theoretical values, the results show that this sensor has a wide dynamic range with the first natural frequency at more than 1600 Hz, working bands (±5%) are more than 400 Hz, and the step response oscillation is intense. This study can provide a reference for the application of the six-axis F/T sensor in the field of dynamic measurement.

Sound radiation by the bladder cicada cystosoma saundersii

1998 ◽  
Vol 201 (5) ◽  
pp. 701-715 ◽  
Author(s):  
H Bennet-Clark ◽  
D Young
Keyword(s):  
Resonant Frequency ◽  
Sound Production ◽  
Ventral Surface ◽  
Major Elements ◽  
Sound Pulse ◽  
Resonant System ◽  
Song Frequency ◽  
The Masses ◽  
Quality Factor Q ◽  
Sound Pulses

Male Cystosoma saundersii have a distended thin-walled abdomen which is driven by the paired tymbals during sound production. The insect extends the abdomen from a rest length of 32-34 mm to a length of 39-42 mm while singing. This is accomplished through specialised apodemes at the anterior ends of abdominal segments 4-7, which cause each of these intersegmental membranes to unfold by approximately 2 mm. <P> The calling song frequency is approximately 850 Hz. The song pulses have a bimodal envelope and a duration of approximately 25 ms; they are produced by the asynchronous but overlapping action of the paired tymbals. The quality factor Q of the decay of the song pulses is approximately 17. <P> The abdomen was driven experimentally by an internal sound source attached to a hole in the front of the abdomen. This allowed the sound-radiating regions to be mapped. The loudest sound-radiating areas are on both sides of tergites 3-5, approximately 10 mm from the ventral surface. A subsidiary sound-radiating region is found mid-ventrally on sternites 4-6. Sound is radiated in the same phase from all these regions. As the abdomen was extended experimentally from its resting length to its maximum length, the amplitude of the radiated sound doubled and the Q of the resonance increased from 4 to 9. This resonance and effect are similar at both tergite 4 and sternite 5. <P> Increasing the effective volume of the abdominal air sac reduced its resonant frequency. The resonant frequency was proportional to 1/(check)(total volume), suggesting that the air sac volume was the major compliant element in the resonant system. Increasing the mass of tergite 4 and sternites 4-6 also reduced the resonant frequency of the abdomen. By extrapolation, it was shown that the effective mass of tergites 3-5 was between 13 and 30 mg and that the resonant frequency was proportional to 1/(check)(total mass), suggesting that the masses of the tergal sound-radiating areas were major elements in the resonant system. <P> The tymbal ribs buckle in sequence from posterior (rib 1) to anterior, producing a series of sound pulses. The frequency of the pulse decreases with the buckling of successive ribs: rib 1 produces approximately 1050 Hz, rib 2 approximately 870 Hz and rib 3 approximately 830 Hz. The sound pulse produced as the tymbal buckles outwards is between 1.6 and 1.9 kHz. Simultaneous recordings from close to the tymbal and from tergite 4 suggest that the song pulse is initiated by the pulses produced by ribs 2 and 3 of the leading tymbal and sustained by the pulses from ribs 2 and 3 of the second tymbal. <P> An earlier model suggested that the reactive elements of the abdominal resonance were the compliance of the abdominal air sac volume and the mass of the abdomen undergoing lengthwise telescoping. The present work confirms these suggestions for the role of the air sac but ascribes the mass element to the in-out vibrations of the lateral regions of tergites 3-5 and the central part of sternites 4-6.

scholarly journals Feasibility Study on Tension Estimation Technique for Hanger Cables Using the FE Model-Based System Identification Method

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Kyu-Sik Park ◽  
Taek-Ryong Seong ◽  
Myung-Hyun Noh
Keyword(s):  
Finite Element ◽  
System Identification ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Inverse Analysis ◽  
Finite Element Models ◽  
Fe Model ◽  
Identification Methods ◽  
System Identification Method ◽  
Model Based

Hanger cables in suspension bridges are partly constrained by horizontal clamps. So, existing tension estimation methods based on a single cable model are prone to higher errors as the cable gets shorter, making it more sensitive to flexural rigidity. Therefore, inverse analysis and system identification methods based on finite element models are suggested recently. In this paper, the applicability of system identification methods is investigated using the hanger cables of Gwang-An bridge. The test results show that the inverse analysis and systemic identification methods based on finite element models are more reliable than the existing string theory and linear regression method for calculating the tension in terms of natural frequency errors. However, the estimation error of tension can be varied according to the accuracy of finite element model in model based methods. In particular, the boundary conditions affect the results more profoundly when the cable gets shorter. Therefore, it is important to identify the boundary conditions through experiment if it is possible. The FE model-based tension estimation method using system identification method can take various boundary conditions into account. Also, since it is not sensitive to the number of natural frequency inputs, the availability of this system is high.

scholarly journals The Evolving Dynamic Response of a Four Storey Reinforced Concrete Structure during Construction

2012 ◽  
Vol 19 (5) ◽  
pp. 1051-1059 ◽  
Author(s):  
A. Devin ◽  
P.J. Fanning
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Natural Frequency ◽  
Structural Response ◽  
Vertical Vibration ◽  
Fe Model ◽  
Structural Elements ◽  
Reinforced Concrete Structure ◽  
Load Bearing ◽  
Lateral Response

Structures include elements designated as load bearing and non-load bearing. While non-load bearing elements, such as facades and internal partitions, are acknowledged to add mass to the system, the structural stiffness and strength is generally attributed to load bearing elements only. This paper investigates the contribution of non-load bearing elements to the dynamic response of a new structure, the Charles Institute, in the grounds of University College Dublin (UCD) Ireland. The vertical vibration response of the first floor and the lateral response at each floor level were recorded at different construction stages. The evolution of the structural response as well as the generation of a finite element (FE) model is discussed. It was found that the addition of the non-load bearing facades increased the first floor natural frequency from 10.7 Hz to 11.4?Hz, a change of approximately +6.5%. Similarly these external facades resulted in the first sway mode having its frequency increased by 6%. The subsequent addition of internal partitions, mechanical services and furnishings resulted in the floor natural frequency reducing to 9.2 Hz. It is concluded that external facades have the net effect of adding stiffness and the effect of internal partitions and furnishings is to add mass. In the context of finite element modelling of structures there is a significant challenge to represent these non-structural elements correctly so as to enable the generation of truly predictive FE models.

scholarly journals A Case Study of Analysis of Natural Frequency Variability Related to Manufacturing Process

2010 ◽  
Vol 17 (4-5) ◽  
pp. 537-550
Author(s):  
T. Uhl ◽  
W. Lisowski
Keyword(s):  
Rapid Prototyping ◽  
Natural Frequency ◽  
Manufacturing Process ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Point Of View ◽  
Modal Testing ◽  
Fe Model ◽  
Structural Dynamic ◽  
Traditional Manufacturing

One of the important challenges present nowadays in the automotive industry is minimizing of a car components design time. Traditional manufacturing of a prototype is usually a time and a cost consuming process. Alternatively, rapid prototyping techniques can be used in such a case. In the reported research a brake caliper was investigated, since it is an example of an element, which should have very strictly defined structural dynamic properties. As a technique of rapid prototyping of the considered caliper the 3D printing of a mould was selected. A process of the caliper casting with the use of the "prototype" mould is different than the one with the use of the metal form. Thus it is very likely that the both considered types of the caliper would possess different properties from the point of view of structural dynamics.Structural dynamic properties can be analyzed both numerically and experimentally. Simulation of the caliper FE model with uncertain parameters was used to analyze influence of various caliper parameters on its natural frequency values. Modal testing of the caliper was performed with the aim of investigation of applicability of Experimental Modal Analysis for determination of variability of natural frequencies resulting from the manufacturing process. In the course of this research, the natural frequencies of the prototype caliper and the standard caliper were compared.

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