Multiobjective Optimization Techniques Applied to Engineering Problems

Conventional equipment for muscular rehabilitation and training uses passive load systems. This work seeks the creation of an alternative resistance generation device for the skeletal muscle contraction to be applied in conventional machines of muscular training and physiotherapy. The proposed device uses a group spring-follower-cam to produce the resistance and does not use cables, belts or chains. The device was designed to generate mechanical resistance through low inertia set, accessibility, modular and low-cost to be adapted on training machines. This device consists of a cam-follower pair connected to a compression spring. Its operating principle is based on the pressure angle variation between the cam-follower pair. The mathematical modeling and the numeric solution for the cam profile is presented. It was noted that prototype can be applied in high speeds unlike conventional equipment. The maximum torque curve available and the torque curve obtained in the device approached, as the movement training approached motor gesture, with maximum errors of about 10 %. The results confirm that the device is capable of generating a resistance profile that resembles the maximum available torque profile at the joint user when performing certain movement training, which can more adequately represent the motor gesture to be trained. Two case studies were conducted using the motor gesture of judo training and rower’s movement which mainly uses elbow flexion.

In the 1960’s, Brånemark and colleagues developed a dental implant system using a direct attachment to bone structure without generating soft tissue. This phenomenon called osseointegration involves biomechanical behavior of materials. In several studies it has been verified that the surface treatment on titanium implant has been the main factor for the osteogenesis process and, consequently, osseointegration [1, 2, 3]. Treated titanium surfaces have better conditions for cell adhesion that can lead to load application in the shortest time. The aim of this study was to evaluate the surface energy and the cell osteogenesis on titanium discs under different conditions of blasting and acid attack. Osteoblastic cells Hfob 1.19 were used to measure cell culture parameters like cell viability and cell proliferation, alkaline phosphatase activity and mineralized nodule formation. Osteogenesis cell was defined through a mathematical model proposed by a similitude in engineering with osteogenic parameters analyzed in culture cells. Fowkes Theory was used to calculate the surface energy by measuring contact angles between liquid sensors (Deionized Water, Chloroform) on different titanium surfaces. Significant difference (P < 0,01) was observed for surface energies ranging between 26,76 a 33,81 mJ/m^2 using ANOVA and Bonferroni test. It was noted that the highest surface energies are related with osteogenesis levels.