Fadiga do aço para molas de válvulas SAE 9258 produzido industrialmente por lingotamento convencional e contínuo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A new method for extending the range of conductive polymer sensors for contact force

This paper describes a technique for extending the force range of thin conductive polymer force sensors used for measuring contact force. These sensors are conventionally used for measuring force by changing electrical resistance when they are compressed. The new method involves measuring change in electrical resistance when the flexible sensor, which is sensitive to both compression and bending, is sandwiched between two layers of spring steel, and the structure is supported on a thin metal ring. When external force is applied, the stiffened sensor inside the spring steel is deformed within the annular center of the ring, causing the sensor to bend in proportion to the applied force. This method effectively increases the usable force range, while adding little in the way of thickness and weight. Average error for loads between 10 N and 100 N was 2.2 N (SD = 1.7) for a conventional conductive polymer sensor, and 0.9 N (SD = 0.4) using the new approach. Although this method permits measurement of greater loads with an error less than 1 N, it is limited since the modified sensor is insensitive to loads less than 5 N. These modified sensors are nevertheless useful for directly measuring normal force applied against handles and tools and other situations involving forceful manual work activities, such as grasp, push, pull, or press that could not otherwise be measured in actual work situations.

Evaluation of grinding fluids in the grinding of a martensitic valve steel with CBN and alumina abrasives

In this paper the performances of different cutting fluids and grinding wheel types were analysed in the grinding of SAE HVN-3 workpieces. The resulting residual stress, wheel wear and roughness were evaluated. The influence of the cutting fluid jet velocity v(j) was also analysed. As a conclusion, the lubrication ability seems to be the governing factor in the cutting fluid performance. The use of CBN wheels can significantly reduce the thermal damage in grinding, leading to compressive residual stresses. The CBN wheel and the cutting oil give an optimum combination for performing this grinding operation.

Evaluation of roof slope and exposure with different roofing materials in reduced models of animal production facilities in spring and summer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)