Mechanical & Fluid Systems

Pulse-tube Refrigerators can be operated over a wide range of temperatures. These units can be used in numerous space and commercial refrigeration applications, including food refrigerator/freezers, laboratory freezers, and freeze dryers. Pulse-tube Refrigerators can also be used to cool detectors and electronic...

A paper suggests the development of a hybrid rocket engine and associated equipment for returning a sample of material from Mars at relatively low cost. In a hybrid rocket engine, a solid fuel is burned by use of a liquid or gaseous oxidizer, the flow of which can be throttled to control...

An improved system for measuring tensions in multiple bolts is based on the usual measurement of the times of propagation of ultrasonic waves along the bolts, but the quantities measured and the method of processing the measurement data differ from those of conventional ultrasonic bolt-tension...

An automated apparatus calibrates digital torque analyzers that, in turn, are used to verify the accuracies of torque wrenches. The apparatus is located in a central laboratory, and the digital torque analyzers are brought to the laboratory for calibration. Previously, the torque analyzers...

A report discusses flexible microactuators for a proposed generation of small, mobile, special-purpose robots. Aspects of this topic were discussed in two previous articles in NASA Tech Briefs: "Thin-Film, Light-Energized Bimorph Micromechanical Actuators" (NPO-19607), Vol. 20, No. 8...

A brief report summarizes the design of the lightweight, high-torque wheel drive of a small robotic vehicle used to explore the surface of Mars. Planetary gearing was selected for compactness and high torque capability. The input stages were fitted with ball bearings to survive the cold (down to -100 °C) Martian...

A technique for applying controlled test pressures to curved surfaces is based on a principle similar to that of a compartmented pilot's or astronaut's pressure suit. The technique involves the use of airbags that accommodate geometric complexity in both the surface under test...

A report presents information compiled from a search of the literature on failure modes of mechanical systems. The report was written to provide a reference base for the application of first-order reliability methods to mechanical systems in the development of a system-level design methodology. In...