Static force control

The instrument for determination of shear moduli was a Rheometric Scientific dynamic mechanical thermal analyzer, model DMTA V. Round shear sandwich geometry was used. The instrument was inverted so that the sandwich fixtures and sample were in water. A water-jacketed 1000 mL Pyrex cylinder supplied by Rheometric Scientific allowed control of temperature with a circulating temperature bath. A sinusoidal linear shear was applied by moving a flat plate between two identical disk-shaped samples over a specified range of frequencies. The two identical disk-shaped samples were sandwiched between the moving plate and two 12 mm diameter plates (called studs) fastened to a frame. The dynamic frequency sweeps to obtain the loss shear modulus, G", from 0.16 Hz to 318 Hz were reported in log scale. For our purposes the applied initial static force was 0.05 N. Sample size was 12 mm diameter and 0.7 mm thickness. The sample was equilibrated at 40°C for 12 hours prior to starting the series of measurements. Shear moduli were measured from high to low temperature with an equilibration time of 2 hours at each temperature. The sequence of measurements was 40°C, 30°C, 25°C, and 15°C. 

Motion transducen A transducer used to measure the controlled output of a servomechanism usuaUy understood to include transducers for static force measurements. 

Heinrichs, B. and Sepehri, N. (1999) A limitation of position based impedance control in static force regulation theory and experiments, Proceedings ofl 999 IEEE International Conference on Robotics and Automation, 3 2165-70. 

Equation 2 implies that the maximum acceleration or its equivalent inertial force controls the seismic failure of stmctures. This type of failure is the case of a brittle stmcture which collapses if the external load exceeds the resistance see Fig. 4. Because traditional masonry buildings and wooden houses were of brittle nature, seismic design by means of this static seismic design... 

Cobalt(II) chloride was dissolved in poly(amide acid)/ N,N-dimethylacetamide solutions. Solvent cast films were prepared and subsequently dried and cured in static air, forced air or inert gas ovens with controlled humidity. The resulting structures contain a near surface gradient of cobalt oxide and also residual cobalt(II) chloride dispersed throughout the bul)c of the film. Two properties of these films, surface resistivity and bullc thermal stability, are substantially reduced compared with the nonmodified condensation polyimide films. In an attempt to recover the high thermal stability characteristic of polyimide films but retain the decreased surface resistivity solvent extraction of the thermally imidized films has been pursued. 

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