Aerodynamic Pressure Mapping Technique from CFD to FEM Model of N219 Winglet

Due to relatively complex geometry of N219 winglets, CFD simulations have to be conducted to predict the aerodynamic load by the structure in some critical flight conditions. Since the aerodynamic CFD model is not the same as the finite element model of the structure, there is a need to accurately transform the load data between the two models. This paper discusses a simple alternative technique to map pressure distribution from the mesh or face zone of a CFD simulation to an FEM model using a Matlab based in-house code program. The technique focuses on how an FEM shell element has same pressure value with its nearest CFD element. Although the cumulative forces sometimes give different result, the pressure distribution is highly accurate, moreover when the FEM model has smoother elements. Validation has been conducted by comparing with other pressure mapping technique of a commercial software Patran. The results show a good agreement where the present technique provide a more accurate result especially for the critical biggest load among the cumulative forces in the three-dimensional direction. The proposed technique is currently suitable to evaluate loading characteristics of semi monocoque structures. A further treatment of the technique for other types of structure is currently under development.

Evaluation of Meniscal Load and Load Distribution in the Canine Stifle after Tibial Plateau Levelling Osteotomy with Postoperative Tibia Plateau Angles of 6 and 1 Degrees

Objectives The aim of the study was to investigate the kinetic and kinematic changes in the stifle after a tibial plateau levelling osteotomy (TPLO) with a postoperative tibia plateau angle (TPA) of either 6 or 1 degrees. Study Design Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs from adult Retrievers.Hinge plates were applied and a sham TPLO surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty per cent bodyweight was applied to the limbs with the stifle in 135 degrees of extension. Each knee was tested with intact cranial cruciate ligament (CCL), deficient CCL, 6 degrees TPLO and 1degree TPLO. Results Transection of the CCL altered kinematics and kinetics. However, comparing the intact with both TPLO set-ups, no changes in kinematics were detected. After 1 degree TPLO, a significant reduction in the force acting on both menisci was detected (p = 0.006). Conclusions Tibial plateau levelling osteotomy restores stifle kinematics and meniscal kinetics after transection of the CCL ex vivo. The contact force on both menisci is reduced significantly after TPLO with a TPA of 1 degree. Increased stifle flexion might lead to caudal tibial motion.

Prototype for Knee-load Relief through Ischiatic Support

Objective: The objective of this work was to develop a passive exoskeleton prototype for the relief of knee-load employing ischiatic body weight support. Methods and materials: A functional prototype was developed and tested with three volunteers to analyze its potential effectiveness and effects on gait kinematics. The performance of the prototype was assessed using motion capture and pressure mapping systems, and a testing bench for the study of ischiatic body weight. Results and discussion: The results of the tests indicate that the prototype allows reducing the load supported by the knees and does not have a significant effect on the kinematics of the hip and knee joints. The process allowed the designers to identify possibilities of improvement mainly on reducing the restrictions imposed by the prototype to the motion of the ankles, especially on the midstance of the support phase. Conclusions: The passive exoskeleton prototype developed for ischiatic body weight support allows setting different percentages of knee-load relief. The prototype does not have a significant effect on the kinematics of the hip and knee joints. Nevertheless, improvements must be performed to reduce the restrictions to the motion of the ankles.