1/6/2024 0 Comments Impulsive force modelsTherefore, the force measurement encounters many problems in an impulse facility, particularly for large and heavy models. The post-processing of the balance signal thus becomes extremely difficult when an averaging method is employed. However, when the force tests are conducted in a shock tunnel, the inertial forces lead to low-frequency vibrations of the test model and its motion cannot be addressed through digital filtering because a sufficient number of cycles cannot be found during a shock tunnel run. Therefore, the traditional internal strain-gauge balance was considered for the force tests use in this large impulse facility. The performance tests demonstrated that this facility is capable of reproducing a flow of dry air at Mach numbers from 5 to 9 at more than 100 ms test duration. A preliminary analysis was performed on the real gas effects on the aerodynamic force.įorce tests were conducted at the long-duration-test shock tunnel JF12, which has been designed and built in the Institute of Mechanics, Chinese Academy of Sciences. The test results show differences from the numerical simulations and some data obtained in a conventional wind tunnel. The impulse force-measurement system performed well in the present tests. As an integrated measuring system, the impulse force-measurement system expands the structural design concept of strain gauge balances. The current measurement technique breaks the limitations of the application of the conventional strain gauge balance. An integrated design of the impulse force-measurement system was proposed for load measurement over a short duration, for which a recommended design criterion is that the measurement period be a minimum of twice the period corresponding to the lowest natural frequency of the measurement system. Force tests were conducted for a cone in the JF-10 high-enthalpy shock tunnel in the Institute of Mechanics, Chinese Academy of Sciences. This study presents an impulse force-measurement system, which was used for a large-scale test model to measure its drag in a high-enthalpy shock tunnel with an approximately 3–7-ms test time. ![]() However, the application of these tunnels is limited due to the only milliseconds-long test duration, especially for aerodynamic force measurement using traditional strain gauge balances. Flight velocity at a high Mach number can be simulated for aerodynamic testing of chemically reacting flows. Stability and relative displacement are calculated for imaginary tetrahedral failure blocks to compare with the yield acceleration and observed settlement, respectively.Shock tunnels are important ground test facilities that can generate high-enthalpy flow. Yield acceleration read off the truncated accelerograms shows a remarkable increase with a decrease in a width to depth ratio of the embankment, demonstrating restraining effects of the valley walls. Accelerograms observed on the failure mass are found to give a truncated waveform with an abrupt drop at the end, as well as concavity associated with three dimensional geometry of the failure mass. ![]() The system is capable of producing an impulsive inertia force with a triangular waveform, and giving rise to a three dimensional failure mass in the embankment. ![]() A simple test equipment system has established to provide the embankment model made of wet sand with well-controlled impact loads. A fundamental study by means of a series of model tests followed by several analyses was performed to clarify dynamic failure characteristics of V-shaped sloping embankments subjected to impulsive loadings. Despite numerous experiences of serious earthquake damages, little knowledge has been obtained about dynamic failure mechanism for sloping embankments constructed in narrow valleys.
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