Search

Nowadays, programmable logic controllers (PLC) are widely used in many automated systems, especially for the control of various actuators. The most common PLC programming is performed by either using a ladder diagram or a structured text. The paper presents the automatic generation of PLC programs for the purpose of sequentially controlling pneumatic actuators. In this paper, the pneumatic actuators are supplied and controlled by 5/2-way as well as 5/3-way bistable pneumatic valves with electric activation. The valve type depends on the number of positions in which the actuator should come, and the position sensors are used for detecting its movement. The characteristic encoding of the movement of actuators, position sensors and control commands is performed. The advantages of the automatic generation of the PLC commands and the entire program described in this paper are illustrated in a real example. [ABSTRACT FROM AUTHOR]

Composite laminates consisting of passive and multi-functional materials represent a powerful material system. Passive layers could be made of isotropic materials or fiber-reinforced composites, while piezoelectric ceramics are considered here as a multifunctional material. The paper is focused on linear and geometrically nonlinear dynamic analysis of smart structures made of such a material system. For this purpose, a linear 3- node shell element is used. It employs the Mindlin-Reissner kinematics and the discrete shear gap (DSG) technique to alleviate the transverse shear locking effects. The electric potential is assumed to vary linearly through the thickness for each piezoelectric layer. A co-rotational formulation is used to handle the geometrically nonlinear effects. A number of examples involving actuator and sensor application of piezoelectric layers are considered. For the validation purposes, the results available in the literature and those computed in Abaqus are used as a reference. [ABSTRACT FROM AUTHOR]