1,185 research outputs found
Fitting of criteria
No full textS.257-269The objective function (Bhatti, Practical optimization methods: with mathematica applications, Springer, New York, 2000 [1]; Brandt et al, Criteria and methods of structural optimization, Martinus Nijhoff Publishers, PWN - Polish Scientific Publishers, Dordrecht, Warszawa, 1986, [2]; Rao, Engineering optimization: theory and practice. Wiley, Hoboken, 2009, [3]) for fitting of the criterion to the measured data can be formulated in many ways, which lead to different results. The following three kinds of objective functions mathematical, physical, and geometrical can be considered (Altenbach et al, Plasticity of pressure-sensitive materials. Springer, Berlin, pp 49-152, 2014, [4]; Kolupaev et al, Strength hypothesis applied to hard foams Appl Mech Mater, 70, 99-104, 2011, [5])
Applications
No full textS.313-356In order to illustrate the application of the criteria and fitting of the parameters, some measurements from the literature are analyzed. At first, the measured data for BLgray cast iron (Coffin and Schenectady in J Appl Mech 17:233-248, 1950) [1], BLPOM (poly(oxymethylene)) (Pae in J Mater Sci 12:1209-1214, 1977) [2], BLPVC (polyvinyl chloride) hard foam (Christensen et al. in Int J Solids Struct 39(4):973-982, 2002) [3], and BLconcrete (Lee et al. in Nucl. Eng. Des. 227(2):143-153, 2004) [4] are shown in (Altenbach et al. Plasticity of pressure-sensitive materials. Engineering Materials. Springer, Berlin, 2014) [5] and (Kolupaev et al. J Eng Mech (ASCE), 2017) [6]. The measured data for BLaluminum alloy (Naghdi, Rowley in J Mech Phys Solids 8:63-80, 1954) [7], (Naghdi et al. in Trans ASME J Appl Mech 6:201-209, 1958) [8], BLPA 6 (polyamide) (unpublished), BLEPP P 9240 (expandable polypropylene) hard foam (Münch, Mechanisches Kurzzeitverhalten von thermoplastischen Konstruktionsschaumstoffen unter mehrachsiger Beanspruchung, 2005) [9], and BLconcrete (Tasuji in The behavior of plan concrete subject to biaxial stress, 1976) [10], (Tasuji et al. in ACI J Proc 75(7):306-312, 1978) [11], (Tasuji et al. in Mag Concr Res 31(109):217-224, 1979) [12] are fitted below. In addition, the own experimental results for PMI (polymethacrylimide) hard foams are evaluated
LIFE JOURNEY: MEDICAL AND SCIENTIFIC WORK OF PROFESSOR V.A. SOKOLOV
No full textThe article is dedicated to doctor of medicine, professor V.A. Sokolov. In 2017 he celebrates his eightieth birthday. Professor V.A. .Sokolov is one of the founders of polytrauma treatment in USSR and Russia. For a long time he had been heading polytrauma department at the N.V. Sklifosovsky Research Institute for Emergency Medicine. Due to his work, algorithms of life sustaining and recovery of serious patients were developed. Professor V.A. Sokolov is the author of 6 monographies and about 300 periodical papers. Besides, he is the holder of 32 patents. Some of his inventions were popularized and manufactured. He had been leading active scientific work, which resulted in 6 doctoral dissertations and 15 candidate theses. The staff of N.V. Sklifosovsky Research Institute for Emergency Medicine congratulates on the anniversary
Summary and outlook
No full textS.357-365The concept of the equivalent stress is a simple and traditional engineering way to solve problems related to the strength prediction or material behavior modeling. The topic is quite old and referable to the normal stress hypothesis of Galileo Galilei (Sect. 4.1). However, the concept is still developing and this trend will continue along with progress in physics, materials science, advanced measurement technics, and numerical methods
Visualization of standard criteria
No full textS.123-138The strain criterion, the MohrâCoulomb criterion, the Sdobyrev, PisarenkoâLebedev criterion, and the BurzyÅskiâYagn criterion are often used for approximation of measured data of the plane stress state: They are easy to handle and can be applied to describe intermediate range between the absolutely brittle and ideal ductile material behavior. © 2018, Springer International Publishing AG
Conditions and assumptions of strength criteria
No full textS.151-158The equivalent stress concept (Sect. 1.2) is an engineering tool. There are no physical principles (e.g., balance equations in Continuum Mechanics, Altenbach, Kontinuumsmechanik: Einführung in die materialunabhängigen und materialabhängigen Gleichungen, Springer, Berlin, 2015, [1]; Altenbach and Altenbach, Einführung in die Kontinuumsmechanik, Teubner, Stuttgart, 1994, [2]) underlying such a formulation. This chapter summarizes the necessary conditions and the most important plausibility assumptions providing reliable criteria for the real-life applications. In particular, recent developments of criteria are discussed as well as the need of a generalized hypothesis
Experiments and equipment
No full textS.271-312Multiaxial tests are usually intricate and not adapted to each other. In this chapter, some effective ways for material testing with the following comparison of the results are suggested. The most important multiaxial tests for hard foams are proposed and implemented. Based on these tests, recommendations for further improvements of the experiment setups are given. Open questions are listed
Formulations of classical strength hypotheses
No full textS.89-99The dimensioning of structural members is usually carried out under the assumption that materials behave either brittle or ductile. The following hypotheses which correspond to one of the two assumptions are often used for strength or yield evaluation (Filonenko-Boroditsch, Festigkeitslehre, Technik, Berlin, 1960, [1]; Gol'denblat, Kopnov, Yield and strength criteria for structural materials (in Russ.: Kriterii prochnosti i plastichnosti konstrukzionnych materialov), Mashinostroenie, Moscow, 1968, [2]; Malmeisters, Tamuzs, Teters Mechanik der Polymerwerkstoffe, Akademie-Verlag, Berlin, 1977, [3]; Sähn et al. Bruch- und Beurteilungskriterien in der Festigkeitslehre, Fachbuchverlag, Leipzig, Köln, 1993, [4]). Because of their simplicity they have established themselves in the engineering practice
Alternative formulations of standard criteria
No full textS.139-149The classical hypotheses describe the extremal states of material behavior (Chap. 4). In order to establish the ductile-brittle transition, the classical hypotheses can be combined by one or two parameters Lüpfert, Beurteilung der statischen Festigkeit und Dauerfestigkeit metallischer Werkstoffe bei mehrachsiger Beanspruchung. Dt. Verl. für Grundstoffindustrie, Leipzig, [1], e.g., the Mohr-Coulomb and the Sdobyrev, Pisarenko-Lebedev criteria (Sect. 6.3). Several further expressions for combination of the classical hypotheses are possible, e.g., the Hoek-Brown criterion (Sect. 2.2.17) and the UST of Yu (Sect. 2.3.5). These formulations can be an advantage for particular materials
Introduction
No full textS.1-11If a solid body component is mechanically loaded, the question of the maximum bearing capacity arises. An evaluation of the strength for uniaxial stress (tension and compression) is relatively simple and widely investigated. Whereas the multi-axial stress states which arise in the body are complex, and the limit behavior is not well understood. The limit behavior can be captured with the failure criteria
- …
