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Rodichev Y.,Gs Pisarenko Institute For Problems Of Strength
Challenging Glass 2 - Conference on Architectural and Structural Applications of Glass, CGC 2010 | Year: 2010

The composite load bearing glass elements have the many advantages as compared with the massive glass structures [1, 2]. The use of high strength, plasticity or viscous behavior of the additional structural elements increases the safety and strength of glass composite. However, the main peculiarities of glass composite mechanical deforming, strength and fracture are remain induced by the primary influence of elastic and brittle nature of glass components on the whole composite structural behavior [1]. The technical approach for the assessment and management of the strength and durability of composite glass elements was developed basing on this position. The management of glass composite strength foresees the use some control tests of the mechanical state of glass components in the composite together with the specific constructional and technological solutions for strength increasing and maintenance in different service conditions [1-5]. Some results of the assessment and management of quality, strength and life time of the annealed and strengthened glass elements as the components of composites with increased carrying capacity are discussed in a paper. Copyright © with the authors. All rights reserved.

Orynyak I.V.,Gs Pisarenko Institute For Problems Of Strength | Lokhman I.V.,Science Ukrtransgas | Okhrimchuk S.O.,Science Ukrtransgas
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2010

Pipe bend is very complicated element for the structural integrity assessment. Up to day there is no conventionally adopted technique for limit load calculation of pipe bend even without any defect. The problem is that at application of outer bending moment the pipe bend cross section ovalizes and the process of deformation can be described only with accounting for the geometrical nonlinearity. The paper deal with limit load calculation for pipe bend with axial part-through defect for particular case when circumferential stresses originated both from inner pressure and outer bending moment dominate over axial stresses from the moment and axial force. Two extreme cases are considered at start. First one is the action of the inner pressure only. The "Institute for Problems of Strength limit load model" (IPS model) can be applied here without any restrictions. The second case is consideration of circumferential bending stresses which have appeared due to ovalization from the outer bending moment. The model of the transmission of stresses from the defected region to the undamaged regions is suggested and the resulting formula for the stress concentration (or strength reduction) coefficient is obtained. At last the simultaneous action of both loadings is considered. As result the analytical formula for the reference stress calculation which is similar in appearance to that of API 579 for accounting for membrane stress as well as bending stress is suggested. The only difference is that strength reduction coefficients are considered for both the membrane stresses from inner pressure and bending stress from ovalization. This differs from API 579 approach where the influence of the defects length on the bending stresses is not taken into account. Copyright © 2010 by ASME.

Rodichev Y.,Gs Pisarenko Institute For Problems Of Strength | Yevplov Y.,Gs Pisarenko Institute For Problems Of Strength | Soroka H.,Gs Pisarenko Institute For Problems Of Strength | Veer F.,Technical University of Delft | And 2 more authors.
Challenging Glass 3: Conference on Architectural and Structural Applications of Glass, CGC 2012 | Year: 2012

Statistical distribution of the data on the bending strength of float glass systematically deviates from the Weibull statistic distribution [1-3]. It was shown that surface defects formed under glass processing and handing are the cause of the multi linear nature of the Weibull plots. The results of an experimental study of statistical distribution of bending strength values were obtained in view of the effect of mechanical treatment and contact loads on glass surface damaging and strength. The shapes and sizes of fracture sources - critical micro-cracks and damages were investigated. It was shown that the statistical behavior of structural glass strength may be controlled by monitoring critical surface defects, conditions of their formation in production of load carrying glass structures basing on experimental strength data. © 2012 The authors and IOS Press. All rights reserved.

Orynyak I.V.,Gs Pisarenko Institute For Problems Of Strength | Bohdan A.V.,Gs Pisarenko Institute For Problems Of Strength | Lokhman I.V.,Science Ukrtransgas
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2012

The problem of smoothing the spatial line based on position measurements of discrete points exists in cases where a) the positions of points are determined with some errors, b) the goal of smoothing is not a continuous position itself but the higher derivatives of it. It is a very common problem in many engineering applications. With respect to the pipeline industry this problem is very prominent at least in two cases but regretfully many researchers do not pay due attention to it at all. First, the Geopigs are widely used for the determination of spatial position of the pipe centerline points. This information inter alia may be (and in fact are widely) used for the calculation of the global centerline curvatures which are proportional to the global bending strains. Second, the maximum strain levels of the dents are calculated based on the local geometry of the dent as determined by radial sensor measurements from the in line inspection survey. Note, that in both cases mathematically the curvatures are the second derivatives of the function of global (pipeline) or local (dent) positions. The input information about the global X-Y-Z position of each consecutive point of axis line as well as the local radial position of the dent points are given with some error. This leads to a huge noise in predicted curvatures which can overrun the useful information. The amplitude of errors of calculation is inversely proportional to the squared distance between the points of measurement. The application of any smoothing procedure may lead to the loss of the useful information about real curvatures. Thus tradeoff between the smoothing of thenoise and the loss of accuracy presents a big problem in the pipeline industry. Two quantitative parameters are introduced here to allow performing such a tradeoff. First parameter characterizes the standard deviation (also referred to as standard in the following) of the random value of the position measurement accuracy by the devices, ρ. Second parameter is the requested accuracy of the curvature determination and is defined in terms of the standard deviation of the bending stress, σ or strain, ε. The spatial beam on elastic foundation model is used to fit the measured point positions to the spatial curve. Its main characteristic is the specific compliance of the foundation α which is determined based on two above root-mean-square errors ρ and σ. The corresponding formulas and tables based on the solution for the elastic beam are obtained. The bigger the allowed error in bending stress σ the lesser is required compliance of the foundation, α. In turn this leads to the smaller value of characteristic wave length of solution and the possibility to retain more useful information about the actual short length stresses in the pipeline. Some practical examples of applications of the procedure are given.Copyright © 2012 by ASME.

Orynyak I.V.,Gs Pisarenko Institute For Problems Of Strength | Yakovleva E.S.,Gs Pisarenko Institute For Problems Of Strength
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2012

The through - wall crack opening area is one of the main calculation parameters for the "leak before break" analysis of the piping system with postulated through crack. The existing methods for calculation of COA, in fact, consider the shell (pipe) to be a flat body and neglect the linear components across the pipe wall thickness (as in the theory of plate) both of load distribution as well as displacement field. Based on the combining weight function method the simple procedure for determination of approximate expression for the fundamental displacement field under polynomial loading of the crack surfaces in the shell as a sum of the uniform and linear components is proposed. Based on this method the formulas for calculating COA at the polynomial membrane and linear loading are derived. The comparison of the obtained COA values with results existing in the literature is performed for the cylindrical shell with axial and circumferential cracks. The contribution of the linear component of the COA to its total value has been estimated. Copyright © 2012 by ASME.

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