1,721,157 research outputs found
DISPOSITIVO DI MISURA ESAPODALE PER LO STUDIO DELLA FATICA MULTIASSIALE DI COMPONENTI MECCANICI
No full textL'acquisizione degli spostamenti e deformazioni di un componente meccanico, generalmente non è un'operazione semplice, soprattutto se il componente ha una geometria complessa e le deformazioni coinvolgono più di un grado di libertà. Gli strumenti, generalmente, utilizzati per questo tipo di misurazione consentono di effettuare misure spesso molto semplificate. In questo lavoro viene presentato un nuovo dispositivo di misura, basato sulla teoria della piattaforma di Stewart, capace di misurare la deformazione globale di un componente acquisendo contemporaneamente tutti e sei i gradi di libertà di spostamento. Per ottenere gli spostamenti nei sei g.d.l. è stato sviluppato un apposito programma, scritto in ambiente Matlab, per risolvere la cinematica diretta del dispositivo. I risultati ottenuti dalla cinematica diretta sono stati confrontati con quelli ottenuti da un modello CAD 3D del dispositivo mostrando una perfetta correlazione. E'stato realizzato un prototipo del dispositivo e testato su un banco prov
Sensitivity analysis of a six degrees of freedom displacement measuring device
No full textObject of this paper is the performance analysis of a six degrees of freedom measuring device based on a modified Stewart platform structure. Because of the device studied in this work represents a novel application of a Stewart like platform, an investigation about its performance has been done, in order to evaluate both behaviour and characteristics of this device in different geometrical configurations. In particular, sensitivity analysis has been carried on about geometrical characteristics and displacements amplitude. To calculate the sensitivity, the inverse kinematic equations of the device have been obtaine
Multi-dofs MEMS displacement sensors based on the Stewart platform theory
No full textThis work proposes a new detection strategy suitable for MEMS sensors with up to 6 degrees of freedom. Parallel structures based on the Stewart theory are commonly adopted as actuators in many fields such as high precision manipulators, aircraft and vibration simulators and machine tools; the same configuration was used here to define the kinematics of a displacement sensor in the microscale based on the optical detection. The algorithm for the estimation of absolute positions and orientations of the platform is presented. The described sensing approach considerably simplifies the platform architecture and design and introduces a promising solution for many MEMS sensors and device
Six d.o.f. displacement measuring device based on a modified Stewart platform
No full textAcquisition of the displacements and deformations of a loaded component is generally a not easy operation. This is especially the case as the component often presents a complex geometry and the deformations involve more degrees of freedom or a combination of them. Measurement devices used for this kind of application often allow to obtain simplified measurements. This paper presents a novel measurement device, consisting of six displacement sensors mounted as a parallel mechanism, capable to measure the global deformation of a component in terms of translations and rotations. The deformations are obtained by applying the direct kinematic equations to convert the six displacements read from the six sensors into the three translations and rotations representing the deformation of the component. The geometry of the device leads to write simplified equations for the direct kinematic that can be solved with a semi-numerical procedure implemented in a program written in Matlab environment. The results given by this procedure have been validated with the positions obtained from a 3D CAD model of the device, showing perfect agreement between the results. A prototype has been made and tested on a workbenc
Experimental and theoretical investigation about reaction moments in misaligned splined couplings
No full textThis paper deals with the uneven loads generated when splined couplings work in misaligned conditions. These loads are balanced by the shafts bearings and they have to be taken into account by designers during the calculation of splined transmission systems. In particular an experimental investigation about tilting moment has been carried on by means of a dedicated test rig, in order to better understand this phenomenon. Experimental tests have been conducted in order to investigate the effect of misalignment angle, transmitted torque and tooth stiffness on the tilting moment. Also a numerical model has been developed in order to obtain a preliminary quick estimation of tilting moment value
Analysis of a load application point in spline coupling teeth
Full text linkThe objective of this paper is to investigate the position of the resultant force in involute spline coupling teeth due to the contact pressure distribution for both ideal and misaligned conditions. In general, spline coupling teeth are in contact all along the involute profile and the load is far from uniform along the contact line. Theoretical models available in publications consider the resultant contact force as it is applied at the pitch diameter, and this study aims to evaluate the error introduced within the confines of a common approximation environment. This analysis is carried out through using finite element method (FEM) models, considering spline couplings in both ideal and misaligned conditions. Results show that the differences between the load application diameter and pitch diameter are not very obvious in both ideal and misaligned conditions; however, this approximation becomes more important for the calculation of the tooth stiffnes
Applicabilità di una nuova tecnica FEM per la simulazione dinamica di piastre piane ricoperte di materiale viscoelastico
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