Transient dynamic response of a nanocomposite conical shell with a ring stiff-ener under the action of an impact load

This work is devoted to the study of transient processes occurring in a nanocomposite shell with a ring stiffener under the action of an impact load. Nanocomposites are promising new materials for the aerospace industry. However, the analysis of dynamic processes in nanocomposite structures requires the development of new methods due to the anisotropic, functional-gradient nature of these materials. The problem is further complicated if a composed structure is to be analyzed. This paper proposes a model of deformation of a functionally graded composite conical shell reinforced with carbon nanotubes with an isotropic ring stiffener. The deformation of the functionally graded nanocomposite conical shell is described by Reddy’s high-order shear theory, and the deformation of the ring stiffener is described by the Euler–Bernoulli hypotheses. The Rayleigh–Ritz method is used to study the natural vibrations of the composite structure. The main variables are the displacements and angles of rotation of the conical shell. A mathematical model of the transient response of the structure under the action of an impact load is obtained in the form of a linear dynamic system in generalized coordinates. To obtain this system, the prescribed form method is used. Numerical studies of the free dynamics and transient response of a nanocomposite conical shell with an isotropic ring stiffener of rectangular section under the action of an impact load were carried out. The results of the numerical modeling of the transient process in the shell showed a close agreement with the results of finite element modeling in the ANSYS package. The effect of the ring stiffener on the amplitudes of the transient response of the nanocomposite shell is investigated. It is shown that the ring-stiffener significantly reduces the amplitude of the transient response of the composite conical shell when it is subjected to an impact load. The proposed method and the conclusions drawn may be used in the aerospace industry in the design of nanocomposite units for multistage launch vehicles.

Buckling Analysis of Stiffened Cone-Cylinder Intersection Subjected to External Pressure

This paper aims to examine the influence of ring stiffener reinforcement on the buckling behavior of cone-cylinder intersection subjected to external pressure. Three different stiffener locations were analyzed; they are (i) cone-cylinder intersection, (ii) cone mid-section, and (iii) cylinder mid-section. Internal and external stiffeners are used in the study. Buckling strength of the stiffened cone-cylinder intersections were obtained with the aid of FE analyses for all the cases above. Cone-cylinder intersections are modelled as elastic-perfectly plastic of Hiduminium alloy (HE-15). Validations of the present results with the published experimental data were presented. Result indicates that the introduction of stiffener reinforcement in externally pressurized cone-cylinder intersections seemed to be desirable in a preliminary design process, thus promotes a stronger shell to resist buckling.

Seismic Performance of Exterior Steel Ring-Stiffener Joint

We study the seismic performance of the exterior steel ring-stiffener (ESRS) joint, a member that is used to connect a steel beam to a square steel tubular column filled with steel fibre recycled concrete for seismic resistance. To this end, the influence of seismic factors such as axial compression ratio and beam-column linear stiffness ratio on seven specimens is studied. A physical test is conducted on the specimens with a series of cyclic loadings. The testing and analysis of hysteretic loops and skeleton curves of the ESRS joints revealed the seismic performance characteristics including failure mode, rigidity, ductility, bearing-capacity degradation, and energy dissipation capacity. The results reveal (a) damage to the specimens at the beam-end near the joint, (b) no failure at the joints’ core area and column, (c) appearance of a plastic hinge at the beam-end near the joint, and (d) plump spindle-shaped hysteretic loops and normal rigidity degradation curves in the specimens. The specimens are then simulated with the finite element method (FEM) and the results are compared with those of the physical test.

CONTINUOUS ELEMENT FORMULATIONS FOR COMPOSITE RING-STIFFENED CYLINDRICAL SHELLS

This research studies the free vibration of composite ring-stiffened cylindrical shells by the continuous element method (CEM). The dynamic stiffness matrix (DSM) of the investigated structure has been constructed based on the analytical solutions of the governing equations of motion for composite cylindrical shells and annular plates. By applying the powerful assembly procedure of continuous elements method, natural frequencies and harmonic responses of composite ring-stiffened cylindrical shells have been obtained. In addition, the proposed model allows extracting exactly ring-stiffener vibration modes by choosing appropriate points of response. Numerical examples have confirmed many advantages of the developed model.

The Research of Strengthening Measures to the Space Type KK-Intersecting Nodes in the Steel Pipe Tower of Power Transmission

At present, the round steel pipe section is used more often in the transmission tower. This paper introduces the strengthening measures to the steel pipe node, which shows that ring-stiffener is a kind of very good strengthening measure. Then it is focus on the research of ultimate bearing capacity of the space type KK-intersecting nodes by the ANSYS finite element analysis software. Try to find the differences between the node with ring-stiffener and without ring-stiffener. Get the conclusions through the analysis and comparison, and provide a reference for practical engineering.