Fernando Viadero Rueda

Planet Load Sharing Behavior During Run Up

The objective of this paper is to study the effects of meshing phase between planets and the planet position error on the load sharing behavior in planetary gear set during run up regime. These effects will be studied numerically and will be validated experimentally through a back-to-back planetary gear test bench by comparing strains in the pinhole of each planet.

Experimental Investigation on the Influence of Relative Density on the Compressive Behaviour of Metal Mesh Isolator

Vibrations, considered one of the major problems in the engineering applications, are analyzed to predict their detrimental effects on the equipment and structures. The metal mesh isolator, named also metal rubber, has become widely applied to mitigate the disturbing vibration due to its special production techniques. Metal rubber is a kind of novel style porous damping material that is manufactured via a process of wire-drawing, weaving and compression moulding. This paper investigates the influence on the compression and dissipative behaviour of the metal mesh isolator provided by the relative density. The mechanical properties of five metal mesh samples with cylindrical geometry and with different relative density are obtained from a quasi-static cyclic compression test. The loading-unloading results of the five samples, subjected to a constant compression level, show the strong dependence exerted by the relative density over the compressive properties. Experimental analysis indicated that the porosity affects the stiffness but has an opposite effect regarding the loss factor. By increasing the ratio between the isolator’s and wire’s densities, the nominal stiffness increases, but the reduction of loss factor is obvious.

Effect of Gravity of Carrier on the Dynamic Behavior of Planetary Gears

This work investigates the effect of gravity of carrier on the dynamic behavior of back to back planetary gears in a stationary condition. A tridimensional lumped parameter model is developed in order to study this phenomenon. The gravity of carriers has an effect on the distance between gears and it is included in the model through sun-planets and ring-planets mesh stiffness which influence on the dynamic response of gear. Numerical results are correlated with the experimental results obtained from a back-to-back planetary gear test bench, this test bench is composed of two identical planetary gears sets: reaction gear, where the ring is free and test gear where the ring is fixed. They are connected through two rigid shafts. A fix external load was applied through an arm attached to the free reaction ring. Data Acquisition System acquired signals from accelerometers mounted on the carrier and the ring. The signal processing was achieved using LMS Test.Lab software.

Load Sharing Behavior in Planetary Gear Set

The objective of this paper is to study the effects of meshing phase between planets, the effects of the gravity of carrier and the planet position error on the load sharing behavior in planetary gear set. These effects will be studied numerically under the stationary condition and will be validated experimentally by a back-to-back planetary gear test bench. In this test bench, strain gauges are installed on each planet’s pin hole in order to compare strains in the pinhole of each planet.

Dynamic Behavior of Back to Back Planetary Gear in Presence of Pitting Defects

The diagnosis of rotating machinery such as planetary gearbox running under operating condition is a complex task. Depending on their nature, the defects can be classified into teeth, geometrical or bearing defects. This paper studies the dynamic behavior of a back-to-back spur planetary gear running in stationary condition in the presence of teeth defects. This damage is the pitting and it is located in one tooth of the sun gear. An experimental test is performed by the measurement of the instantaneous accelerations on a test gear. The tests are carried out under a fixed load and speed. The presence of the tooth pitting defect activates repeated-like transient in ring’s vibration displacement because of phase change and amplitude reduction of the mesh stiffness when the damage tooth comes into contact. The Fast Fourier Transform (FFT) is used to transform the time signal into the frequency domain for signature analysis. The acceleration spectra show the influence of damage both in frequency and amplitude. The frequency of pitting which is the frequency of rotation of the test sun and the frequency of rotation of the motor appears along of frequency bandwidth. Moreover, the impulses of the defect tooth with the planets become important in amplitude.

Experimental Investigation of Normal/Lateral Excitation Direction Influence on the Dynamic Characteristics of Metal Mesh Isolator

Vibrations, considered one of the major problems in the engineering applications, are analyzed to predict their detrimental effects on the equipment and structures. The metal mesh isolator has become widely applied to mitigate the disturbing vibration due to its special production techniques. The metal mesh isolator is a kind of novel style porous damping material that is manufactured via a process of wire-drawing, weaving and compression molding. The influencing laws of the manufacturing parameters including the relative density and the working condition together with the excitation direction dependence should be taken into account in the characterization of the metallic wires material. In this paper, the mechanical properties of three models with different relative density will be investigated under different preload masses and for three acceleration levels. A number of experiments can be examined by changing the direction of excitation in order to describe the compression and non-compression molding direction effect on the dynamic behavior. A modal analysis is performed using the rational fraction polynomial method to determine the stiffness and the damping ratio from the measured transmissibility data. According to the reported experimental results, the major factor affecting the mechanical characteristics (stiffness and damping) is the sliding friction that exists at the contact-points between wires.

Transfer Path Analysis of Planetary Gear with Mechanical Power Recirculation

Planetary gears can transmit higher power density levels because they use multiple power paths formed by each planet branches. In order to study the propagation of vibration between components of planetary gear test bench with mechanical power recirculation, an approach to the classical transfer path analysis (TPA) method is used to improve vibration control of planetary gear test bench. This approach termed Global Transmissibility Direct Transmissibility (GTDT) avoids the drawbacks of the classical TPA which are decoupling of the active part in the measurements of the Frequency Response Functions (FRFs) of source-receiver paths and the difficult measurement of the operational forces. The Global Transmissibility Direct Transmissibility (GTDT) is two steps method: the first step is the measurements of transmissibility which requires no disassembly tests and the second step is the measurement of the operational responses which is easier than measurement of the operational forces. In fact, tri-axial accelerometers are mounted in each component of the back-to-back planetary gear test bench and the transfer functions (frequency response functions, FRFs) are measured using hammer impact test in order to measure the global transmissibilities. Then, the direct transmissibilities are computed from the global transmissibilities. Finally, reconstructed operation responses are shown in the partial path contribution (PPC) plots to compare the vibration level of each component and to know its contribution in the transfer of vibration.

Instrumentation of Back to Back Planetary Gearbox for Dynamic Behavior Investigation

The objective of this chapter is to investigate experimentally the dynamic behavior of back-to-back two stages planetary gear under stationary and non stationary conditions. Instrumentation layout for measurement is presented. In order to get signal from carriers, a developed instrumentation is showed: connections are achieved between accelerometer and acquisition system through a hollow slip ring. After that, series of measurements are achieved to study the dynamic behavior of carriers under stationary condition and the influence of the run up regime in the dynamic behavior of carriers.

Vibratory Data Fusion for Gearbox Fault Detection Using Autoassociative Neural Networks

This paper deals with gearbox fault detection by vibration analysis. A new processing procedure is proposed which uses the information from several acquisition channels. The approach is based on the assumption that there is a non-linear relationship among the instantaneous vibration magnitude registered for each measurement location. This relationship is captured in the connection weight matrix of an Autoassociative Artificial Neural Network (AANN), which is trained to provide an output vector equal to the input one. In this work, the time synchronous average signal (TSA) for each channel corresponding to the no fault condition is used to train an AANN. Once the AANN is trained, it is used with new data registers as a linear prediction error filter. If the new register contains the same data structure as the training set the prediction error will be low and the machine is working properly. Otherwise, when the new register differs from the training set, as a consequence of a fault, prediction error will be increased in each channel. In this way the information from not only one channel but more than one is used for fault detection and diagnosis as the error signal depends on the TSA signal from all channels. The proposed approach provides a new tool for gear fault detection that is compared on the basis of experimental registers with the most traditional gear processing tools based on TSA such as residual and regular signals. The possibility of generalizing the net prediction capabilities using a training data set that contains several load cases is also explored.Copyright