For calculation of distribution of tension in a difficult real design there is the most preferable an application of any suitable numerical method realized on modern PEVM now. One of universal numerical methods is the method of final elements (MFE).
For information processing on the COMPUTER the mathematical model of a surface of a product has to be created. It is rather easy to make it when the difficult surface can be broken into elements, each of which represents a cone, the sphere or the site of the plane limited to pieces of straight lines or arches of conic sections. When surfaces are not formed by the elementary elements as, for example, in aircraft industry, it is necessary to look for other decision.
Obolochca () - this module reading out from the file with the dat expansion initial information on dimension of model, quantity of reference points, quantity of the studied surfaces and extent of sampling makes their processing. If it is necessary to make sampling of a surface with feature that input from the file of data of number of a point, its coordinate proceeds and additional extent of sampling, i.e. implementation of points 1 - as a result we receive files with coordinates of knots and the list of final elements which make a basis of basic data for calculation for the programs realizing MKE.
Actually only general property of all these dependences is total absence of any preliminary mathematical definition, even partial therefore the solution of a task began with performance of consecutive steps of approximation and came to an end manually, each step of adjustment was based on results of experiments or it is simple on instructions of the designer. Because of a lack of information such dependences sometimes were called" experimental".
We will consider procedure of sampling of a changeable surface on the example of a cover in which basis the rectangular frame, height in the middle of a design and number of knot which coordinate changes lies.
Further working, as well as in point we break a surface and we receive a grid of knots and, having entered number of changeable knot, its new coordinates and extent of sampling, we carry out a spline through three points: changed, and the closest points of intersection of a curve of Ki with curves of K1 and K And further taking into account in addition entered extent of sampling it is broken into final elements space between i-1 and Ki+1, and also between K1 and K Renumbering of knots is carried out taking into account a new condition. In figure 7 the circle allocated knot which coordinate was changed. Dashed lines showed splines which were constructed in addition.
Apparently (and (a) is similar, and (follows from (a) at hj = to hj-1, i.e. a case with a variable step more general, it also was the basis for the program. As the case of creation of a spline on three points that regional conditions is used (and (a) look as follows:
Quality of the received splitting is estimated visually or determination of the areas of elements (the area is calculated as vector work: if at least one of the areas is negative, splitting is executed incorrectly. Visual survey is useful and when the negative areas are not present.