In order to solve the dynamic buckling problem of elastic cylindrical shell under torsional impact, the original and dual variables of the problem are constructed by means of the energy of the system, and the Hamiltonian system of the system is established. According to the characteristics of Hamiltonian regular equation and symplectic space, the initial boundary value problem of partial differential equation is transformed into an algebraic equation problem by using the boundary conditions and compatibility conditions expressed by dual variables, and the analytical expressions of symplectic eigenvalues and eigensolutions are obtained.
A myriad of investigations have been published on the pharmacologic manipulation of flaps to enhance tolerance to ischemia. We recently reported a threefold increase in ischemic tolerance of the rat abdominal skin flap pedicle after 6 hours of primary ischemia and 12 hours of reperfusion. Flaps underwent normothermic perfusion washout with lactated Ringer's or U.W. solution, a newly developed organ preservation medium. Perfusion washouts were performed at one of three different points in the protocol: (1) onset of primary ischemia; (2) onset of secondary ischemia; or (3) 2 hours after onset of secondary ischemia. The last group was used to simulate the clinical situation in which flaps are discovered and salvage procedures instituted at a delayed time interval. This is the longest normothermic ischemic interval reported. We undertook the present study to determine the utility of the U.W solution in prolonging the tolerance of the flap to a second ischemic insult after a period of reperfusion. Seventy-five unilateral rat abdominal skin flaps were raised. Secondary ischemia was produced by placing a microvascular clamp across the inferior epigastric pedicle. Flap survival was assessed at 1 week postoperatively. While none of the nonperfused flaps survived 8 hours of secondary ischemia, at least 50% of the U.W. perfused flaps survived an average of 14 hours of secondary ischemia. Lactated Ringer's perfusion washout only modestly increased the ischemic tolerance. Perfusion washout in the secondary ischemic phase improved the ischemic tolerance to a significantly greater degree than in the primary ischemic interval. (OTOLARYNGOL HEAD NECK SURG 1993;108:149-55.)
In this paper, the basic governing equations of nonlinear dynamics of solid-liquid coupling system are established. Without considering the free vibration, according to the characteristic polynomial of the Jacobi matrix of the disturbance equation required by the Hopf bifurcation, the algebraic equations that the critical velocity must meet are derived. The numerical results show that when the velocity exceeds the critical value, the vibration amplitude of the beam jumps obviously.
Taking the solid sliding wedge as the research object, the failure surface equation of the sliding wedge and the lateral pressure formula of the shallow silo are established by using the limit equilibrium method. The results show that the location of failure surface changes significantly with the ratio of height to diameter.
When the temperature changes, the stress produced by the external constraint and the mutual constraint between the internal parts of the object, which makes it unable to expand and contract freely, is called thermal stress. The thermal stress is caused by the steady temperature field. When the transient temperature changes to zero and the temperature distribution reaches a stable state, the temperature distribution can be obtained from the heat conduction equation and temperature boundary conditions, and then the displacement and stress can be obtained from the elastic equation including the temperature term.
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