František Menda

Determination of the Necessary Geometric Parameters of the Specimen in Ring-Core Method

There are several measuring techniques for determining residual stress which can be divided according to the created damage in to the construction in non-destructive, semi-destructive and destructive ones. One of the most common is semi-destructive hole-drilling method. This paper deals about Ring-Core method which is based on the similar principles. Today, there is no standard for the Ring-Core method, thus it is important to consider various influential factors. One of them are the dimensions of specimen. Calibration coefficients are determined by finite element (FE) analysis using the commercial software Solidworks. These coefficients are used for residual stress evaluation by incremental method used in Ring-Core method. The influence of different specimen dimensions on the accuracy of the evaluated residual stresses is considered.

The Process of Gait Generation for Snake-Like Robot with Nonholonomic Constraints

The article deals with the issue of the use of geometric mechanics in mobile robotics. In the introductory part of article, basic notions are explained that frequently occurring in the concept of geometric mechanics including definition of the undulatory locomotion. It contains the determination of mathematical model for the kinematic snake-like robot that is expressed in the form of Jacobian. Further was described the relation between the body velocity and the shape variable by the reconstruction equation and from this equation was expressed the local connection. This local connection shown using the vector fields together with the gait were used to analyze movement of the kinematic snake. The last part deals with the height functions that determine the exact value of displacement or rotation in fiber directions.

Verification of the Geometric Parameters of the Ring-Core Method

The Ring-Core method is a semi-destructive method for residual stress determination inside materials. The evaluation of residual stresses using Ring-Core method requires complex analysis of the geometric parameters. This work deals with the uniformly distributed residual stress components through the material thickness.

The Usage of Bond Graphs Methodology for Mechanical Systems Designing

The article deals with the issue of the usage bond graphs at modeling of mechanical systems. In contrast with the classical method, where the equations for individual components are created first and then on their basis the simulation scheme is derived, here the described method uses the reverse procedure. In the introductory part of article the bond graph notation is defined and next basic types of multi-ports are explained. The last part consists of definition of port and power bond between ports that are explained on example of DC motor with separate excitation.

Program Tools for Residual Stress Evaluation by Ring-Core Method

Residual stress determination requirements of production and research users grow rapidly. Commercially available programs enable relatively quick residual stress evaluation with certain level of accuracy and with limited user access to used compliance matrices and calculations. However precise analyses require sensitive approach to compliance matrices determined for individual case e.g. for specific specimen dimensions. Therefore program tools for complex residual stress evaluation by Ring-Core method were developed using finite element analysis and Visual Basic scripts.

Analysis of Differential Method Used for the Evaluation of Uniform Residual Stresses by the Ring-Core Method

Despite the significant advantages of the Ring-Core method over the hole-drilling method, the Ring-Core method is still less common. Recent developments at our department showed the full potential of the method when using the adequate calibration coefficients. In this paper the differential method, a quick and easy method for uniform residual stress evaluation is described and the influence of its relaxation coefficients on the specimen’s dimensions is obtained.

Residual Stress Prediction Using Neural Network Approach

Procedures for residual stress evaluation by using Ring-Core method have not been standardized. Most common techniques are derived from the ones used for similar semi-destructive hole-drilling method. The differences between research approaches can cause significant errors. New approach using neural network is proposed as a more adaptive way for residual stress evaluation than the commonly used methods.