This Publication

Plate members are widely used in modern lightweight construction. In order to reduce the mass of these structures, while preserving an adequate stiffness at the same time, the thickness of the plate should be as small as possible and the stability is gained by introducing stiffeners. Depending on their rigidity, there are two possible buckling modes for the plate. For flexible stiffeners, the resulting mode is a global one in which the stiffeners bend with the plate. Beyond a particular value of their stiffness, the critical stress of the plate remains constant and the resulting mode is a local buckling mode of the sub-panels of the plate. The goal is to find the cross-section dimensions of stiffeners beyond which the increase in stiffness will no longer affect the value of the critical buckling stress. This paper presents a procedure to get optimized cross-section dimensions for longitudinally stiffened plates under compression with two flat stiffeners. The cross-section is optimized using MATLA algorithms according to the buckling plate theory. The finite element models are used to confirm the optimization process.

In this paper an automatised method for kinematic analysis of human body segments in CAD environment has been established. 3D coordinates of marked points on lower extremities recorded by the ELITE measuring system and Kistler force plate were the input data for the computer simulation, which calculates and reconstructs the spatial orientation and trajectories of human body joints. Within this research, special attention is focused on the study of locomotion during energy-demanding movements like stair climbing, as an activity that requires large amount of metabolic energy and thus represents great difficulty in performing daily activities for people with disorders of the musculoskeletal system. Using this technique, the characteristic percentages of stance period during stair climbing have been determined, at which the knee joint makes a characteristic loop on its trajectory, in order to allow the conversion of muscle energy into potential energy when lifting the body to a higher level of the next stair.

Tracking of human body motion is applied in many fields, such as virtual reality, clinical biomechanics, the study of man-machine-environment relationship, the analysis of sports movements, etc. Nowadays, the preferred approach to tracking human body motion is based on the use of appropriate optical or magnetic markers, which are placed on specific landmark points, and real-time estimating of their spatial coordinates. With the improvements introduced in computerized monitoring of human motion kinematics, it is important to emphasize the significance of combining motion capture data with commercial CAD packages. The aim of this research was to develop new interactive methods in creating virtual models within the highly sophisticated CAD computer technologies, as well as computer simulations for analyzing the various forms of human locomotion. Within this research, special attention is focused on the study of locomotion when climbing stairs, as an activity that requires large amount of metabolic energy, and thus represents great difficulty in performing daily activities for people with disorders of the musculoskeletal system, and particularly for people with lower limb amputation.