- Open Access
Investigation of strained deformed state of variable stiffness rod
© Tsarenko and Ulitin; licensee Springer. 2014
Received: 23 January 2014
Accepted: 26 June 2014
Published: 19 July 2014
An equation for bending of a weighable rod with variable transversal stiffness was proposed. On the basis of this analyses the conclusions were drawn about the influence of parameters of construction on values of maximum sag and maximum bending moment. The recommendations for the usage of the simplified model were done. The example of the construction with given parameters for calculation of stiffness and strength according to the represented mathematical models was considered.
Different models of rods are used for investigation of building constructions which are under the influence of longitudinal and transversal loads (Editor Madugula 2002). For example, such models in stability and dynamics problems were used in the works (Yoo 2011; Strommen Einar 2014; Yang 2005). For the first time the differential equation of longitudinal bend of rods of variable section under the influence of point load was considered in the paper (Ostwald 1889). Stability under the influence of distributed longitudinal load for pointed rods was investigated by L. Bairstow (Bairstow L, Jones BM, Thompson BA 1913). Analytical solution of the common problem for the constructions, which are under the influence of longitudinal point and distributed loads, is not found in literature. In practice, when the model of equivalent rod is used, the influence of longitudinal loads on the value of transversal deformation and bending moment is not taken into account or calculated methods are used (Editor Madugula 2002). The accurate definition of the model, taking into account longitudinal and transversal loads, is a new problem.
getting formulas for investigation of strained deformed condition of a rod which is a model of a construction of a lattice tower under the influence of longitudinal and transversal loads;
valuation of the influence of longitudinal loads on the value of transversal deformation and bending moment.
where , or .
We find common solution of inhomogeneous equation (7) by the method of arbitrary constants variation.
The Wronskian of the fundamental system of functions , (Ostwald 1910), then , W ≠ 0 because v is not an integer figure.
where Sμ,ν(z) - Lommel functions (Watson 1922).
where ; .
Using the formulas (10-13) it is possible to calculate stiffness and strength, where constant integrations С1 − 4 are defined from bordering conditions for fastening or joint of construction parts.
- 2.We get maximum values of loads for using the model (1) exactness of which is up to 5% for pointed rod (k = 001), it is represented in graphics of Figure 5,
and for maximum sag definition;
and for maximum moment definition.
For example, a boring rig, which represents a rod construction in the form of a square truncated pyramid, has the following parameters: rig height is 53,3 m, width of the low base is10 m, of the upper one is 2 m (h1 = 1 м; h2 = 5 м; k = 0,25; a = 0,075), transversal section area is 351,4 ⋅ 10− 4 m2, rig weight is 4 ⋅ 105 N (), equipment weight 3,2 ⋅ 106 N (). The ratios of sags and moments form, y2,max/y1,max = 1045; M2,max/M1,max = 1022 for it, so the error of the model (1) use for the definition of sag is 4,5% and of moment in the base is 2,2%.
The graphs in Figures 3, 4 and 5, show that in the common case the longitudinal load influences the calculated parameter values. So, when investigating a strained deformed condition of a structure presented above, it is necessary to use this suggested model or on its base to ground established tolerances in calculated schemes.
The problem, which is under consideration in this paper, is a tower type constructions model under the influence of point load and distributed loads. This model can be used for the investigation of strained deformed condition of constructions, for solving problems of stability and for mathematical description of elements in program modeling complexes on the base of finite elements method.
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