Journal of Mechanisms最新文献

The input-output displacement equation is expressed as a polynomial of degree eight in half-tangents of the output angular displacement by eliminating two extraneous unknowns from three equations presented in a previous paper [2] of which this is a continuation. Two elimination procedures are presented. The results are illustrated by a numerical example.

Link mechanisms can produce prolonged dwells of the driven link in extreme positions.

A five-link plane mechanism with two degrees of freedom is examined in this work. Using certain properties of the mechanism under applied load, we obtain a mechanism with one degree of mobility. On examining such a mechanism with a slide, a form is obtained where the driven link in extreme positions has prolonged dwells.

The relationship between the mechanism's parameters necessary to get the designed motion of the driven link is obtained.

In modern machine assemblies and transport machines, various elastic couplings are extensively used for connecting the driving and the working machines.

The paper makes a study of the vibrations induced in a machine assembly with an elastic coupling having piecewise linear characteristics. A system of differential equations is obtained describing the motions of the machine for the general case of an arbitrary number of concentrated masses, taking into account the dynamic characteristics of the driving machine. Methods for the construction of a periodic solution of the system of equations of motion are also considered. The discussion is followed by an illustrative example.

A general formulation to calculate critical dimensions such as the maximum practical outside diameter and the maximum face width of face gears in their general contact condition is presented. For the case of a face gear in mesh with an involute spur pinion on an intersecting orthogonal shaft, the necessary equations to calculate these critical dimensions are derived from the analysis.

A kinematic analysis of the four-link spherical mechanism is developed utilizing Euler's angles. The relations of the Euler angles to the link positions are derived. Furthermore, Euler's equations for the motion of a rigid body about a fixed point are used to analyse the dynamics of the same mechanism.

There are bounds to the usefulness of the simple three-piece cam mechanism, in particular, bounds to its ability to produce a wide swing of the follower arm. By coupling a four-bar linkage in tandem, it becomes possible for this output angle to be even greater than 180°, depending on the goodness of the transmission angle that is wanted and on how small the maximum acceleration must be.

The general character of a mechanical system and its boundaries is discussed. Formalization of the analysis is accomplished by introduction of the concepts of the kinematic “influence coefficients” of velocity, acceleration, force, power inertia, etc., thereby making optimization through digital programming more feasible. It is possible to determine the response of mechanical systems to known energy, force, or power crossing the boundaries through the utilization of these influence coefficients. The effect of coulomb friction on the response is also shown to be predictable, a feature which enables the designer to better analyze or design mechanically constrained systems.

This research into oscillations of an elastically suspended coupler of a four-bar linkage includes the solution of a coupled system of Hill's differential equations. Having derived the equations of motion, the instability ranges and both the amplitudes and bearing forces are computed for the case of different approximations for a given example.