The Experts below are selected from a list of 38829 Experts worldwide ranked by ideXlab platform

Paolo Decuzzi - One of the best experts on this subject based on the ideXlab platform.

  • the state of stress induced by the plane frictionless cylindrical contact ii the general case elastic dissimilarity
    International Journal of Solids and Structures, 2001
    Co-Authors: M Ciavarella, Paolo Decuzzi
    Abstract:

    Abstract In Part I of the paper, the authors have studied the contact problem between a pin and an infinite plate containing a conforming hole, in the absence of friction and in the case of elastic similarity, obtaining a closed form result which generalizes the identical materials analysis of Persson (On the stress distribution of cylindrical elastic bodies in contact, Ph.D. dissertation, 1964). Here, in Part II, the general case of contacting materials is first studied numerically, finding that the effect of elastic dissimilarity (i.e. the second Dundurs' constant not being zero) is negligible for the dimensionless pressure distribution, the maximum influence being less than 2%. Vice versa, the influence on the relation between the contact area arc semi-width, e, and the dimensionless Loading Parameter E 1 ∗ ΔR/Q is indeed significant; however, considering as an approximate pressure distribution the one of the elastically similar case, an extremely good approximation is obtained for the general relation e vs. E 1 ∗ ΔR/Q which can now take into account of both Dundurs' elastic Parameters. In particular, the limiting value for elim, towards which the contact tends under very high loads both under initial clearance or interference (or for any load for the perfect fit limiting case) is given as a function of both Dundurs' elastic Parameters, α, β as well as the load when complete contact is lost in an interference contact, ecompl. Hence, a complete assessment of the strength of the contact can be obtained directly from the results of Part I of the paper, given that for a certain contact area extension, the correct value of load is used.

  • the state of stress induced by the plane frictionless cylindrical contact i the case of elastic similarity
    International Journal of Solids and Structures, 2001
    Co-Authors: M Ciavarella, Paolo Decuzzi
    Abstract:

    The contact problem between cylindrical conformal surfaces, modelling for instance a fastener joint, is studied. A closed form solution is obtained in Part I of the paper for the case of elastic similarity, improving (i) the solution obtained by Persson (On the Stress Distribution of Cylindrical Elastic Bodies in Contact, Ph.D. dissertation, 1964), which was also limited to identical materials, and (ii) the results of Noble and Hussain (Int. J. Engng. Sci. 7 (1969) 1149), which were limited to the case of perfect fit of contacting materials. The variation of the contact area, pressure distribution and maximum sustainable load is given for the complete range of possible dimensionless Loading Parameter E1*?R/Q and first Dundurs' material Parameter, ?. Under conditions of initial clearance, the contact area arc, var epsilon, increases with load from zero to a limiting value, var epsilonlim, which depends only on the material Parameter ?. Vice versa, under conditions of initial interference, the contact is complete until there is detachment and the contact area starts to decrease with load up to the same limiting value, var epsilonlim, which is also the only possible value of contact area for neat-fit conditions, under any applied load. Finally, a complete assessment of the strength of the contact is given for the entire range of working conditions. As expected, the strength of the joint decreases rapidly if the extent of the contact area reduces, and finally tends to the limit predicted by the Hertzian theory when the arc of contact is smaller than about 30°. The optimal conditions for avoiding yielding are reached for a contact arc smaller than the limiting arc var epsilonlim: this means that it is not possible to reach the optimum from a configuration of initial interference.

H Meng - One of the best experts on this subject based on the ideXlab platform.

  • pulse Loading shape effects on pressure impulse diagram of an elastic plastic single degree of freedom structural model
    International Journal of Mechanical Sciences, 2002
    Co-Authors: H Meng
    Abstract:

    Abstract Pulse Loading shape effects on the dynamical response of an elastic–plastic, single-degree-of-freedom (SDOF) structural model are studied in the present paper. Two dimensionless Parameters are introduced to classify the studied problem into elastic, elastic–plastic and rigid–plastic structural responses. When structural damage is controlled by maximum structural deflection, a characteristic curve in Loading Parameter space can be used to define an isodamage curve, i.e., pressure–impulse diagram, which is generally Loading-shape-dependent. Dimensionless Loading Parameters, termed as effective Loading Parameters, are introduced in the present paper to give unique Loading-shape-independent pressure–impulse diagram for each response category.

  • pressure impulse diagram for blast loads based on dimensional analysis and single degree of freedom model
    Journal of Engineering Mechanics-asce, 2002
    Co-Authors: Qingming Li, H Meng
    Abstract:

    Characteristics of a pressure-impulse diagram for blast loads are studied based on a dimensional analysis and a single-degree-of-freedom model. Structural behavior is dominated by the fundamental elastic response mode and the structural damage is controlled by the maximum structural deflection. The blast Loading is simplified into a descending pressure pulse. A characteristic curve in nondimensional Loading Parameter space is used to define an isodamage critical diagram, pressure-impulse diagram, to distinguish damaged and undamaged ranges in the Loading Parameter space. Three damage regimes on a pressure-impulse diagram, i.e., (I) impulse-controlled damage, (II) peak load and impulse-controlled damage, and (III) peak load-controlled damage, exist respectively for impulsive, dynamic and quasistatic structural response regimes determined by the ratio between Loading time and the response period of a structure. It is observed that there is a noticeable Loading shape influence on the pressure-impulse diagram...

Y T Feng - One of the best experts on this subject based on the ideXlab platform.

  • on the determination of the path direction for arc length methods in the presence of bifurcations and snap backs
    Computer Methods in Applied Mechanics and Engineering, 1999
    Co-Authors: E A De Souza Neto, Y T Feng
    Abstract:

    Abstract This paper discusses the choice of the sign of the incremental load factor in the predictor solution phase of arc-length methods. It is shown that the criterion recently proposed by Y.T. Feng, D. Peric, D.R.J. Owen, [Determination of travel directions in path-following methods, Mathl. and Comput. Modelling 21 (1995) 43–59; A new criterion for determination of initial Loading Parameter in arc-length methods, Comput. Struct. 58 (1996) 479–485] produces a reliable path direction prediction even in the presence of bifurcations and/or `snap-backs', when some popular criteria may fail to predict the continuation direction. The robustness of the criterion is illustrated in a numerical example where finite element solutions are obtained to a structural stability problem characterised by the existence of several bifurcation paths and `snap-back' phenomena.

  • a new criterion for determination of initial Loading Parameter in arc length methods
    Computers & Structures, 1996
    Co-Authors: Y T Feng, D Peric, D R J Owen
    Abstract:

    The arc-length method has been extensively applied in the last decade to trace solution paths in nonlinear static structural problems. The sign of the Loading Parameter increment in the predictor phase of the method, however, must be determined according to some criteria which are not well established. By further investigation of the approach within the framework of continuation methods in this paper, a new criterion has been proposed, which can be incorporated into both direct and iterative solvers, and has proved to be very successful for the test problems considered.

M Ciavarella - One of the best experts on this subject based on the ideXlab platform.

  • the state of stress induced by the plane frictionless cylindrical contact ii the general case elastic dissimilarity
    International Journal of Solids and Structures, 2001
    Co-Authors: M Ciavarella, Paolo Decuzzi
    Abstract:

    Abstract In Part I of the paper, the authors have studied the contact problem between a pin and an infinite plate containing a conforming hole, in the absence of friction and in the case of elastic similarity, obtaining a closed form result which generalizes the identical materials analysis of Persson (On the stress distribution of cylindrical elastic bodies in contact, Ph.D. dissertation, 1964). Here, in Part II, the general case of contacting materials is first studied numerically, finding that the effect of elastic dissimilarity (i.e. the second Dundurs' constant not being zero) is negligible for the dimensionless pressure distribution, the maximum influence being less than 2%. Vice versa, the influence on the relation between the contact area arc semi-width, e, and the dimensionless Loading Parameter E 1 ∗ ΔR/Q is indeed significant; however, considering as an approximate pressure distribution the one of the elastically similar case, an extremely good approximation is obtained for the general relation e vs. E 1 ∗ ΔR/Q which can now take into account of both Dundurs' elastic Parameters. In particular, the limiting value for elim, towards which the contact tends under very high loads both under initial clearance or interference (or for any load for the perfect fit limiting case) is given as a function of both Dundurs' elastic Parameters, α, β as well as the load when complete contact is lost in an interference contact, ecompl. Hence, a complete assessment of the strength of the contact can be obtained directly from the results of Part I of the paper, given that for a certain contact area extension, the correct value of load is used.

  • the state of stress induced by the plane frictionless cylindrical contact i the case of elastic similarity
    International Journal of Solids and Structures, 2001
    Co-Authors: M Ciavarella, Paolo Decuzzi
    Abstract:

    The contact problem between cylindrical conformal surfaces, modelling for instance a fastener joint, is studied. A closed form solution is obtained in Part I of the paper for the case of elastic similarity, improving (i) the solution obtained by Persson (On the Stress Distribution of Cylindrical Elastic Bodies in Contact, Ph.D. dissertation, 1964), which was also limited to identical materials, and (ii) the results of Noble and Hussain (Int. J. Engng. Sci. 7 (1969) 1149), which were limited to the case of perfect fit of contacting materials. The variation of the contact area, pressure distribution and maximum sustainable load is given for the complete range of possible dimensionless Loading Parameter E1*?R/Q and first Dundurs' material Parameter, ?. Under conditions of initial clearance, the contact area arc, var epsilon, increases with load from zero to a limiting value, var epsilonlim, which depends only on the material Parameter ?. Vice versa, under conditions of initial interference, the contact is complete until there is detachment and the contact area starts to decrease with load up to the same limiting value, var epsilonlim, which is also the only possible value of contact area for neat-fit conditions, under any applied load. Finally, a complete assessment of the strength of the contact is given for the entire range of working conditions. As expected, the strength of the joint decreases rapidly if the extent of the contact area reduces, and finally tends to the limit predicted by the Hertzian theory when the arc of contact is smaller than about 30°. The optimal conditions for avoiding yielding are reached for a contact arc smaller than the limiting arc var epsilonlim: this means that it is not possible to reach the optimum from a configuration of initial interference.

D R J Owen - One of the best experts on this subject based on the ideXlab platform.

  • a new criterion for determination of initial Loading Parameter in arc length methods
    Computers & Structures, 1996
    Co-Authors: Y T Feng, D Peric, D R J Owen
    Abstract:

    The arc-length method has been extensively applied in the last decade to trace solution paths in nonlinear static structural problems. The sign of the Loading Parameter increment in the predictor phase of the method, however, must be determined according to some criteria which are not well established. By further investigation of the approach within the framework of continuation methods in this paper, a new criterion has been proposed, which can be incorporated into both direct and iterative solvers, and has proved to be very successful for the test problems considered.