scholarly journals Vibration-Based Locomotion of an Amphibious Robot

2021 ◽  
Vol 11 (5) ◽  
pp. 2212
Author(s):  
Silvio Cocuzza ◽  
Alberto Doria ◽  
Murat Reis
Keyword(s):  
Elastic Beam ◽  
Experimental Tests ◽  
Spring Steel ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Modes Of Vibration ◽  
Asymmetric Shape ◽  
Locomotion Speed ◽  
The One ◽  
Amphibious Robot

In this research, an innovative robot is presented that can move both on land and water thanks to a vibration-based locomotion mechanism. The robot consists of a U-shaped beam made of spring steel, two low-density feet that allow it to stand on the water surface without sinking, and a micro-DC motor with eccentric mass, which excites vibrations. The robot exhibits stable terrestrial and aquatic locomotion based on the synchronization between body vibrations and the centrifugal force due to the eccentric mass. On the one hand, in aquatic locomotion, the robot advances thanks to floating oscillations and the asymmetric shape of the floating feet. On the other hand, the terrestrial locomotion, which has already been demonstrated for a similar robot, exploits the modes of vibration of the elastic beam. In this study, the effect of different excitation frequencies on the locomotion speed in water is examined by means of experimental tests and a numerical model. A good agreement between experimental and numerical results is found. The maximum locomotion speed takes place when the floating modes of vibration are excited.

scholarly journals Possibilities of Energy Harvesting from the Suspension System of the Internal Combustion Engine in a Vehicle

2021 ◽  
Vol 23 (2) ◽  
pp. B106-B116
Author(s):  
Jacek Caban ◽  
Grzegorz Litak ◽  
Bartłomiej Ambrożkiewicz ◽  
Leszek Gardyński ◽  
Paweł Stączek ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Power Supply ◽  
Fossil Fuels ◽  
Combustion Engine ◽  
Electric Energy ◽  
Elastic Beam ◽  
Experimental Tests ◽  
Suspension System ◽  
Piezoelectric Energy ◽  
Mechanic Energy

The automotive industry faces huge challenge in environmental protection by reducing fossil fuels and energy consumption by developing various practical solutions in energy harvesting. The current analysis is related to the diesel engine power supply system in a passenger off-road vehicle for application of the piezoelectric energy harvesting system. Experimental tests were carried out for the three constant rotational speed values - 800, 1000 and 1500 rpm. The results pertained to operational and simulation tests of available power supply options from the engine suspension system in the vehicle, e.g. to power sensors supervising the engine’s operation or other small electrical devices in the vehicle. The simulations of output voltage were conducted by means of a nonlinear model with a resonator coupled to a piezoelectric elastic beam deformed in the magnetic field to improve the band of frequency transducing kinetic mechanic energy into electric energy.

Kinematic and Electromyographic Analysis of the functional role of the body axis during Terrestrial and Aquatic Locomotion in the Salamander Ambystoma Tigrinum

1992 ◽  
Vol 162 (1) ◽  
pp. 107-130 ◽  
Author(s):  
LARRY M. FROLICH ◽  
ANDREW A. BIEWENER
Keyword(s):  
Muscle Activity ◽  
Functional Role ◽  
The Body ◽  
Ambystoma Tigrinum ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Wave Patterns ◽  
Axial Morphology ◽  
Electromyographic Analysis

Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs -- one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during theoriginal evolution of terrestriality in early tetrapods.

scholarly journals Experimental investigation of leak hydraulics

2012 ◽  
Vol 15 (3) ◽  
pp. 666-675 ◽  
Author(s):  
M. Ferrante ◽  
C. Massari ◽  
E. Todini ◽  
B. Brunone ◽  
S. Meniconi
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Network Models ◽  
Water Distribution Network ◽  
Experimental Tests ◽  
Pressure Control ◽  
Pipe Material ◽  
Governing Equations ◽  
The One ◽  
Definition Of

In recent decades the hydraulics of leaks, i.e. the definition of the relationships linking the hydraulic quantities in pipes with leaks, has received increasing attention. On the one hand, the definition of the relationship between the leak outflow and the relevant parameters – e.g. the leak area and shape, the pressure inside the pipe and outside the leak, and the pipe material – is crucial for pressure control and inverse analysis techniques. On the other hand, if the effect of the leakage on the governing equations is not taken into account, i.e. the loss of the flow axial momentum is not considered, significant errors can be introduced in the simulation of water distribution systems. In this paper, the governing equations for a pipe with a leak are derived. The basic equations, obtained within different approaches, are presented in a consistent formulation and then compared with the results of some experimental tests. The leak jet angle and other major features of the results are analysed. The estimated values of the parameters can be used in the water distribution network models when pipes with a diffuse leakage are considered.

Fracture Evaluation of the Falling Weight Impact Behaviour of a Basalt/Vinylester Composite Plate through a Multiphase Finite Element Model

2017 ◽  
Vol 754 ◽  
pp. 59-62 ◽  
Author(s):  
Felipe Vannucchi de Camargo ◽  
Ana Pavlovic
Keyword(s):  
Finite Element ◽  
Natural Fibers ◽  
Fem Simulation ◽  
Experimental Tests ◽  
Element Model ◽  
Multiphase Model ◽  
Low Velocity ◽  
Weight Impact ◽  
The One ◽  
Falling Weight

Several investigations regarding the mechanical behaviour of composites reinforced by natural fibers under impact have been realized recently, aiming at achieve a low-weight and resistant design. At the same time, progressively accurate results on numerical simulations have been reached powered by modern Finite Element Method (FEM) approaches for composites; however, demonstrating a faithful indentation pattern is still a challenge. The present work aims at building an impact numerical simulation that exhibits a fracture mechanism exactly like the one seen in experimental tests, also carried in this work, on a Basalt Reinforced Composite Polymer (BRFP) plate subjected to low-velocity falling weight impact (IFW). The FEM simulation describes a multiphase model considering each ply and their inter-layer interactions.

scholarly journals Lithium Niobate Micro-transducers matrix design

2019 ◽  
Vol 281 ◽  
pp. 01001
Author(s):  
Hala El Rammouz ◽  
Farouk Benmeddour ◽  
Jamal Assaad ◽  
Emmanuel Moulin ◽  
Lucie Dupont ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Real Time ◽  
Experimental Tests ◽  
Fabrication Process ◽  
Two Dimensional ◽  
Low Frequencies ◽  
Impedance Analyzer ◽  
The Matrix ◽  
The One ◽  
Matrix Design

In this work, a two-dimensional (2D) Lithium Niobate (LiNbO3) 36°Y-cut micro-transducers (μTs) matrix design is presented. Two main steps define the fabrication process: electrode deposition and photolithography. These steps are preceded by the optical mask conception, which defines the 2D matrix pattern. In contrary to the one element case, this μTs matrix allows to automatically scan a desired structure in real time. The μTs matrix is characterized using an impedance analyzer. Furthermore, the experimental tests carried out in order to demonstrate the matrix functionality at low frequencies [200 - 800] kHz are presented.

Effects of Mechanical Preloads on the Rotordynamic Performance of a Rotor Supported on Three-Pad Gas Foil Journal Bearings

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Kyuho Sim ◽  
Bonjin Koo ◽  
Jong Sung Lee ◽  
Tae Ho Kim
Keyword(s):  
Test Data ◽  
High Speed ◽  
Experimental Tests ◽  
Journal Bearings ◽  
Test Results ◽  
Performance Measurements ◽  
Displacement Sensors ◽  
Single Top ◽  
Speed Up ◽  
The One

This paper presents the rotordynamic performance measurements and model predictions of a rotor supported on three-pad gas foil journal bearings (GFJBs) with various mechanical preloads. The rotor with its length of 240 mm, diameter of 40 mm, and weight of 19.6 N is supported on two GFJBs and one pair of gas foil thrust bearings (GFTBs), being a permanent magnet rotor of a high speed electric motor. Each bearing pad consisting of a top foil and a bump-strip layer is installed on a lobed bearing housing surface over the arc length of 120 deg along the circumference. Test three-pad GFJBs have four different mechanical preloads, i.e., 0 μm, 50 μm, 70 μm, 100 μm with a common radial nominal clearance of 150 μm. A series of speed-up tests are conducted up to 93 krpm to evaluate the effects of increasing mechanical preloads on the rotordynamic performance. Two sets of orthogonally positioned displacement sensors record the rotor horizontal and vertical motions at the thrust collar and the other end. Test results show that the filtered synchronous amplitudes change little, but the onset speed of subsynchronous motions (OSS) increases dramatically for the increasing mechanical preloads. In addition, test bearings with the 100 μm preload show a higher OSS in load-on-pad (LOP) condition than that in load-between-pads (LBP) condition. A comparison with test results for a one-pad GFJB with a single top foil and bump-strip layer reveals that three-pad GFJB has superior rotordynamic performance to the one-pad one. Finally, the test data benchmark against linear rotordynamic predictions to validate a rotor-GFJB model. In general, predicted natural frequencies of the rotor-bearing system and synchronous rotor motions agree well with test data. However, stability analyses underestimate OSSs recorded during the experimental tests.

MODELLING OF CHANGES IN SURFACE TOPOGRAPHY IN DRY SLIDING CONDITIONS

Tribologia ◽  
2016 ◽  
Vol 267 (3) ◽  
pp. 61-70
Author(s):  
Andrzej DZIERWA ◽  
Rafał REIZER
Keyword(s):  
Numerical Model ◽  
Surface Topography ◽  
Experimental Tests ◽  
Dry Sliding ◽  
Sectional Area ◽  
Cross Sectional ◽  
Analytical Methodology ◽  
Tribological Tests ◽  
The One ◽  
Worn Surface

Metrology of surface topography is presently so developed that, in some ways, we can predict the surface behaviour of the one part in co-operation with another element. We can single out two main approaches to the modelling of surface texture. In the first one, the modelling does not take into account the conditions of the technological or operational formation of the surface, while in the second, more complicated approach, modelling takes into account the real conditions of forming the surface. In this work, tribological tests were carried out in dry sliding conditions, and the analytical methodology of wear or worn surface. Approximations obtained using the second approach are usually worse than those using the first method [L. 8–10]. In the presented work, tribological tests in dry sliding conditions were carried out, and a numerical model to determine the cross-sectional area of wear in presented conditions was produced, and the results obtained using modelling and experimental tests were compared.

A justification of the one-dimensional linear model of elastic beam

1986 ◽  
Vol 8 (1) ◽  
pp. 502-515 ◽  
Author(s):  
Z. Tutek ◽  
I. Aganović ◽  
J.-C. Nedelec
Keyword(s):  
Linear Model ◽  
Elastic Beam ◽  
One Dimensional ◽  
The One

The postpulmonary septum of Varanus salvator and its implication for Mosasaurian ventilation and physiology

2012 ◽  
Vol 183 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Amy Burnell ◽  
Sean Collins ◽  
Bruce A. Young
Keyword(s):  
Connective Tissue ◽  
Respiratory System ◽  
Lateral Displacement ◽  
Thick Sheet ◽  
Inferior Surface ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Varanus Salvator ◽  
Kinematic Analyses ◽  
Ambush Foraging

Abstract The postpulmonary septum (PPS) is a relatively thick sheet of connective tissue covering the inferior surface of the lungs in varanid lizards. The primary connection of the PPS is to the medial surface of the ribs; additional connections occur to the inferior midline of the dorsal vertebrae, the pericardium, and a direct (through loose connective tissue) link to the surface of the lung. The PPS effectively partitions the coelomic cavity into peritoneal and pleural cavities. Investigation demonstrates that the PPS is not capable of preventing displacement of the more caudal (peritoneal) viscera, which is displaced cranially during terrestrial locomotion; this cranial displacement could impinge on the tidal volume of the lungs. Kinematic analyses of terrestrial and aquatic locomotion in Varanus salvator document the different propulsive mechanics used during movement through these two media, and, most importantly, the marked reduction in lateral displacement of the trunk during swimming. These findings, when combined with previous studies of the cardiovascular and respiratory system of varanids performing terrestrial locomotion, suggest that mosasaurs had a versatile, effective respiratory system and were likely capable of both sustained swimming and prolonged submersion, such as during ambush foraging.

Experimental Validation and Updating of the Flexible Multibody Model of a Commercial 3R Planar Manipulator

2011 ◽  
Author(s):  
Stefano Fiorati ◽  
Emiliano Mucchi ◽  
Raffaele Di Gregorio ◽  
Giorgio Dalpiaz
Keyword(s):  
Ad Hoc ◽  
Low Frequency ◽  
Experimental Tests ◽  
Low Speed ◽  
Operational Conditions ◽  
Multibody Model ◽  
Planar Manipulators ◽  
Flexible Multibody ◽  
Modes Of Vibration ◽  
Synthesis Methodology

Serial planar manipulators are diffusely used either as stand-alone machines or as part of more complex cells, and many commercial planar manipulators are available on the market. These commercial machines are mainly destined to accomplish low-speed tasks, and they are designed by taking into account their flexibility at most in the joints. Unfortunately, there are particular installation conditions in which even low-speed tasks can generate low-frequency vibrations that highly interfere with the task. This aspect is highlighted here with reference to a commercial 3R planar manipulator, and how to manage this problem is explained. In this sight, a flexible multibody model is developed where the flexibility of the frame, the manipulator is fixed to, is modeled over the flexibility of the joints, that is introduced as lumped stiffness. In particular, the flexible frame is included in the model by using a Component Mode Synthesis methodology, in which only the natural modes of vibration and the static constrain modes are accounted. The model is validated through an experimental campaign. The experimental tests consist of several modal analyses, together with acceleration and laser Doppler measurements in operational conditions. This methodology allows to provide a model which takes into account the installation conditions, and gives a tool for studying ad-hoc solutions which prevent the occurrence of low-frequency vibrations.

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