TAILIEUCHUNG - Strength Analysis in Geomechanics Part 3

Tham khảo tài liệu 'strength analysis in geomechanics part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 26 1 Introduction Main Ideas e s IV 0 s III O t t till tiv t Fig. . Stepwise and interrupted loading becomes a constitutive equation of the Plasticity Theory developed here and expressions generalize the approach of maximum loads at unstable deformation. Expressions . . give an opportunity to find all the parameters in rheological law . When we take from the primary parts of creep curves at the same time strains E we can construct diagrams ơ e approximation of which by the power function allows to find the exponent m of the hardening law. Dividing E by ơm we have a creep curve Q t which can be also approximated by a power law . Q Btn. Damage parameter a can be found in two ways either according to the first expressions or by approximation of the third parts of creep curves. Very often the both approaches give near values of a. Eccentric Compression and Determination of Creep Parameters from Bending Tests We take a bar with a width 2h Fig. a and unity thickness loaded by compressive force F with eccentricity e. We use the law of plane cross-sections E ky1 broken line in the figure where k is a curvature and two systems of coordinates - xOy and xOiyi with yi y c. If we apply forces in point O we find axial load N F and bending moment M Fe. We take a material of non-linear creep type at a 0 as p Ơ ro t Ep where ffi Q p. p 1 m 0 p 1 . At ffi constant and p 1 then ffi E we have the Hooke s law - straight line OA in Fig. . If p 0 we receive the perfect plastic body with ffi ơyi p - horizontal straight line in the same figure. With consideration of the expression above for E we derive from -Fig. b. 27 Description of Properties of Soils and Other Materials Fig. . Eccentric compression of bar p rokg yi g rokg y c g Putting into static equations SX 0 EMoi 0 we compute N akg y yi gdyi rokg h c 1 g - h - c 1 g 1 g h c h c M ak ị y1 1 gdy1 - Nc h c Oik 1 h c 2 g h c 2 g

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