Draw diagrams of numerical calculation of inhomogeneous compression foam as an example of flexible

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Structure alfa tech india and properties of gas-filled polymers CALCULATION compression diagram flexible foam WITH REGARD apparent density, the degree of closed cells, the inhomogeneity of the macrostructure, the relaxation properties of polymers - -0SN0VY
Equation (4.1) allows a fairly complete description of the experimental data on the compression of different foams, however, does not explain the specifics of deformability of cellular materials. Indeed, there are several basic types of compression diagrams flexible foams low apparent density, which are represented on ris.4,1 / 3, 4, 25, 53-54, 89 /. It follows from equation alfa tech india (4.1), the type of compression alfa tech india diagrams in Figure 4.1 will not change when not * change the cellular structure. In fact, at constant cell structure (at the same elastic foam samples) at a temperature of 293K may be a compression type 2 diagram, but at higher temperatures - such as I. Moreover, even when the same compression temperature diagram form one and the same elastic foam samples may vary with type 2 (strain at high speeds) to type I at low strain rates / I /.
Nёnnye into squares. Thus all neighboring squares are connected with each other at the corners in mutually perpendicular planes. In anisotropic cell foams are elongated in the direction of foaming. We assume alfa tech india that the square rods rigidly clamped ends in non-deformable volume units
Thus, the height of the assembly much smaller length rods. Assume alfa tech india that at small and large deformations bands operate in a longitudinal-transverse bending of flexible rods, moreover when the critical loads in compression is implemented energetically most favorable buckling straps. The consequence is mentioned hypotheses, taking into account the continuity of the structure, the need for the destruction of foam collective alfa tech india buckling rods entering their ends in a knot. As a structural fragment taken separate strand, which replaced the idealized a calculated member in the form of direct polymer rod zaschemlёnnym end with the same cross-section along the length. If we assume that the relative change in the distance between adjacent nodes gazostr ^ k tural elements is the average strain foam, it is possible to calculate the stresses acting on the ends of the element, and further averaged voltage for the corresponding homogeneous alfa tech india foam.
A more detailed consideration of the particular strands of work does not change the overall picture of the nature of their deformation, and therefore is not a fundamental problem in the set. Quantitative alfa tech india calculation compression diagrams I, 3, 4 types of lung homogeneous elastic foam was made by us / 160 / method using the elastic parameters
Expression (4.3) is a generalized formula diagrams alfa tech india compression homogeneous foams, taking into account the influence of the separate properties of the polymer as the base (taking into account the elastic modulus of the polymer base) and deformability properties of the actual cellular structure (taking alfa tech india into account the rest of the formula 4.3). The inspection revealed a number of cases, a satisfactory agreement between the results of calculation of the experimental data for flexible foams and foam type penopolivinilhlorida / 160 /. However, the real system polymer foams are often more complex and therefore require a more detailed analysis, alfa tech india
Assume that the foam is not uniform and has REPAIRED "ing spectrum allocation stiffness layers of the sample. Takei cause nonuniformity distribution coefficient can be shaped bands of cells in layers on the bulk density distribution of heterogeneity of the polymer elastic modulus and the like of the base. E., That is not essential from the viewpoint of the problem. In this case, compressing the sample in the supercritical region is the weakest first compressed layer is then successively stiffer material layers. Experimentally, it is observed alfa tech india often / I /.
Since the compressive stress for all layers of the sample will be the same, and the deformation of the sample is added from the strain of each layer, the chart compression inhomogeneous foam can be expressed as: r '-r-
Values b'i in (4.4) for each homogeneous layer expressed by the formula alfa tech india (4.3), but is determined by heterogeneity foam (range of distribution layers I / t stiffness).
Draw diagrams of numerical calculation of inhomogeneous compression foam as an example of flexible polyurethane foam-75 apparent density = 45 kg / m3. Numerical solution of equation (4.3) for such a uniform layer of foam in reduced coordinates
Substituting computed from the histogram in Figure 4.3 in