# Comparison of Stress Concentration Factors Obtained by Different Methods
## 1 Introduction  
The determination of stress concentration factors and their subsequent implementation in the design process and condition assessment of structural elements and entire structures is an essential element in the prediction of the behavior of structures affected by the notch effect in different loading regimes. Historically, the problem of the notching effect was initially addressed analytically. However, it was limited to simple shape-discontinuity-dimension-load configurations and to the elastic deformation domain only. The present means of stress-strain analysis allow relatively efficient determination of the stress concentration factors analytically, experimentally and numerically, simultaneously in all their interaction possibilities of comparison and verification. Experimental methods with a significant degree of application include the planar and spatial transmission Photostress(r) method [1]. The obtained data of stress concentration factors are then arranged for the various shape-dimension-load configurations and the basic types of discontinuities of the structures, most often in the form of graphs, nomograms, or various approximation equations, dependencies, etc. Combined, experimental-analytical methods may also be applied. They are relatively faster and more efficient, although the results obtained are less accurate. However, nowadays, a number of new, specific and shape-complex structural elements are emerging for which such information is not available. In such cases, computer simulations and computer modelling are a suitable solution. They make it possible to subject a mathematical model of a real and shape-complex element to specific loads and thus to obtain information on the progress and distribution of stresses and, where appropriate, deformations. Such a model can then be subjected to optimization procedures and subsequently modified as required. An important element is the possibility of statistical and correlation evaluation of the obtained results. Of the available numerical methods, the finite element method is considered to be the most effective and the most widely used,where, with the correct definition of boundary conditions and loads, the correct choice of the type and number of finite elements, etc., it is possible to obtain results comparable to experimental methods. These can then be applied for comparison and verification purposes as independent verification means in justified cases [2,3].  
This paper does not seek to fundamentally question existing data, its sources and methods of acquisition, which have been with us, in some cases, for several decades. On the contrary, for a long period of time, they have been able to be applied relatively successfully in various fields of design and assessment of structural elements and entire structures, specifically from the fields of engineering and construction. However, if there is to be continuous progress and improvement in this field, it cannot only concern the relevant methods of construction and design but also the input data and, in particular, the means of obtaining them quickly, efficiently and economically. This also applies in full to the continuous improvement of the accuracy and relevance of these data. This paper, using the example of a simple and relatively frequently occurring shape-discontinuity-dimension-load configuration, should highlight the relevant state of the art and the associated problems.