1,720,980 research outputs found
Long-term survival after removal of a single brain metastasis from lung carcinoma. 8:215-217, 1995
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Shape Memory Alloys Applied to Automotive Adaptive Aerodynamics
No full textShape memory alloys (SMAs) are gaining popularity in the fields of automotive and aerospace engineering due to their unique thermomechanical properties. This paper proposes a numerical implementation of a comprehensive constitutive model for simulating the thermomechanical behavior of shape memory alloys, with temperature and strain as control variables to adjust the shape memory effect and super elasticity effect of the material. By implementing this model as a user subroutine in the FE code Abaqus/Standard, it becomes possible to account for variations in material properties in complex components made of shape memory alloys. To demonstrate the potential of the proposed model, a skid plate system design is presented. The system uses bistable actuators with shape memory alloy springs to trigger plate movement. The kinematics and dynamics of the system are simulated, and effective loads are generated by the shape memory alloy state change due to the real temperature distribution in the material, which depends on the springs’ geometrical parameters. Finally, the performance of the actuator in switching between different configurations and maintaining stability in a specific configuration is assessed. The study highlights the promising potential of shape memory alloys in engineering applications and demonstrates the ability to use them in complex systems with accurate simulations
Advanced Material Thermomechanical Modelling of Shape Memory Alloys Applied to Automotive Design
No full textThis study introduces an innovative approach to enhancing aerodynamic efficiency in automotive applications by exploiting shape memory alloy technology. To this end, a thorough investigation of the thermomechanical behaviour of these alloys was conducted in the paper. Using a UMAT subroutine, the pseudoelastic effect and the shape memory effect of these smart materials were analysed numerically simultaneously, allowing accurate predictions of their behaviour under different loads, and facilitating the design and optimization of devices and systems based on SMAs. Therefore, the article proposes an innovative solution to optimize aerodynamic efficiency by using a Grille Shutter with variable openings. The Active Grille Shutter uses a bistable SMA actuator, allowing two optimal opening positions for specific load conditions. These actuators hold two stable states without energy consumption, ensuring efficient and reliable operation and allowing rapid transitions between the two states, making them ideal for applications that require timely responses. By using this specially designed and numerically analysed system, it has been confirmed that suitably dimensioned shape memory springs can guarantee a movement of the blades of the 90°, allowing an improvement in vehicle efficiency of about 4% at a speed of 140 km/h
Mesalazine-associated benign intracranial hypertension in a patient with ulcerative colitis
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