About one method for replacing variables for a wavean equation describing vibrations of systems with moving boundaries

An analytical method for solving the wave equation describing the oscillations of systems with moving boundaries is considered. By replacing variables that set boundaries and leave the equation invariant, the original boundary value problem is reduced to a system of functional – difference equations that can be solved using forward and reverse methods. The inverse method is described, which allows us to apply sufficiently diverse laws of boundary motion to the laws obtained from the solution of the inverse problem. New partial solutions for a fairly wide range of boundary motion laws are obtained. A direct asymptotic method for approximating the solution of a functional equation is considered. The errors of the approximate method are estimated depending on the speed of the border movement.

Technical solutions of vibration safety cold riveting performed ship repair

The parameters of heating and cooling of rivets made of steel and aluminum alloy, as well as data of fi lling holes with these rivets during hot and cold riveting are compared. The features of the process of performing cold impact riveting by direct and reverse methods, as well as the possibility of reducing the force of this riveting by improving the closing heads and constructive transformation of the rivets themselves are considered. Features of physiological infl uence of cold shock riveting on hands, elbows and shoulders of workers are determined. Describes the construction of riveting hammers and supports with spring shock absorbers that prevent the disease of workers vibration disease, portable riveting presses of pneumatic and hydraulic action. A description of the press equipment and technology of bolt-riveting connections, allowing mechanizing the process of cold riveting is given.

Study on the Reverse Designing for Water Cavity Model of Engine’s Cylinder Head

The water cavity model of engine’s cylinder head is reconstructed by CAD through slicing method. The reverse design methods which are used for complex interior structure’s surface are explored based on slicing method and using software such as Imageware and UG, through modeling the water cavity. The technologies of reverse design such as the measure method of points cloud, points cloud data treatment, curve fitting, fitting error analysis, surface reconstructive and solid modeling are studied. The reverse methods for complex surface are put forward which are based on blocks and features of model. Through the practice of reversing design for cylinder head water cavity model, it is proven that the complex inner cavity components can be reversed by slicing method. The methods can be referenced for similar reverse design.

Gearing principle and geometric design of conical involute gear pairs with crossed axes

A group of formulae for the geometric parameters, such as the gear mounting distance, crossed-axes angle, centre distance and helix angle of the tooth projection on the reference plane of a reference rack, of a crossed-axes gear drive of different arrangements are derived based on the analysis of the spatial mesh relationship between conjugate gears and their reference rack. A set of geometrical design methods for conical involute gear pairs with crossed axes (non-intersecting and non-parallel axes) is presented. The formulae can be applied not only to all of the possible independent forms of crossed-axes gear drives but also to the case of gearing with parallel axes and intersecting axes. The design methods consist of two parts, the sequential and the reverse methods. The former is used to determine the mounting dimensions when the basic dimensions of a pair of conical involute gears are given, while the latter is used to determine basic dimensions of a pair of gears when the mounting dimensions are known. The formulae and the methods are verified through the design and manufacture of a set of testing gears.