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An existing model for the dynamic analysis of the piston motion in an internal combustion engine has been modified to incorporate a simpler representation of the piston–cylinder interaction, and to represent the main and big-end bearings as lubricated rather than dry journal bearings. The results demonstrate that the differences in calculated bearing forces and output torques are negligible, indicating that the simple dry journal bearing model is sufficient, but show that the modelling of the interaction between piston and cylinder is considerably improved. [ABSTRACT FROM AUTHOR]

A dynamic model is presented for the internal combustion engine in which the primary motion of the pistons is determined by the gas pressure in the cylinders rather than by an assumed steady rotation of the crank, and the secondary motion of the pistons is determined by the interaction of the pistons with the cylinder walls under non-lubricated and fully flooded lubricated conditions. Results are presented for the simulation of a single-cylinder engine and show clearly the variations in the secondary translation and rotation of the piston throughout the engine cycle for the non-lubricated condition, and the significant damping of such secondary motions in the fully flooded lubricated condition. [ABSTRACT FROM AUTHOR]

A vibrating wire strain gauge capable of measuring strains in concrete elements to an accuracy of better than 0.5 μ ℇ is presented. This offers some advantages over conventional electrical resistance gauges, the quoted accuracy of which is typically 3 μ ℇ, and which are often considered unsuitable for concrete because of their inability to span cracks.While vibrating wire gauges are potentially more accurate, they are prone to significant errors because of temperature changes. In the purpose-built gauge described here, temperature correction is achieved using an unstrained reference gauge. The vibration data are analysed using a moving-window Fourier transformation in order to identify and remove the geometrically nonlinear portion of the response. The resulting system is accurate, economical and easy to use. The gauges have been used to study the behaviour of cracked concrete specimens. Typical results are presented and discussed. [ABSTRACT FROM AUTHOR]

The work presented here investigates the possibility of using changes in the nonlinear vibration characteristics to detect damage in reinforced concrete elements. The nonlinear vibration characteristics were studied by conducting impact excitation vibration tests on reinforced concrete beams. The nonlinearities were detected by examining the changes in the fundamental frequency during the decay of an impulse response with time (and hence, with amplitude of vibration). The tests demonstrated that there is a change in nonlinear vibration behavior with damage. The change is greatest at low levels of damage. After the beam has been loaded to 27% of the failure load in three-point bending there is a reversal in the trend and a slight reduction in nonlinearity with further damage. These results indicate that the method is unlikely to be useful in detecting high levels of damage in reinforced concrete bridges, however, it is capable of detecting low levels of damage not visible to the naked eye, and so has potential for assessment of special structures where very high levels of structural integrity are required. [ABSTRACT FROM AUTHOR]