Research On The Moon Landing Buffer Based On Magnetorheological Technique

Moon is rich in mineral resources, the country which is able to land moon can make the mineral resource of moon as the complement of earth energy. So landing moon has a very important significance in economy, science, military affairs and politics. The landing moon robot takes on some important tasks such as exploring, sampling and analyzing. Too big landing crash will damage badly the robot, even cause a failure of the whole landing moon plan. So the study of landing buffer technique is necessary and urgent. MRE can change its elastic modulus obviously for magnetic field effect. Consequently the stiffness is changed. The test apparatus should have these features such as not requiring encapsulation, stable performance and quick response and so on. MRE has a broad applying prospect in the vibrant system which needs controlling the rigidity. Developing a variable stiffness active buffer using MRE, checking the effect of the buffer in damp and landing buffering can offer theory exploring and technical reserve to developing outer space exploring and advanced landing buffer of our country. Theory analysis, machine design, exciter experiment and landing experiment are used in this paper. Mechanical property of MRE, architecture of buffer and test result are studied. The specific works include several parts as following:(1) Expounded the magnetic effect of magnetorheological elastomers, raised the application of MREs in damping and buffering; pointed out the significance in studying moon landing buffer, discussed the progress of the moon landing buffer and noted that the active landing buffer device is the trend development in future, and raised the studying purpose and content of this paper.(2) Analysis magnetorheological elastomer's magnetic properties based on its ferromagnetic particles and matrix viscoelastic; expounded the dipole and coupling field physics model; on the basis of this, calculated the coupled field physics model in which the oblique chain and the magnetic field has a certain angle, revealed the monotonous decline relation between magnetic shear modulus and the angle of the initial state of chain and the direction of the magnetic field, the shear strain of particle chain and the particles'space; revealed the monotonous ascend relation between magnetic shear modulus and the external magnetic field and particle magnetization factor; Meanwhile, quoted the test results of University of Science and Technology of China on MRE shear properties, the results indicated that shear storage modulus increased markedly when the magnetic field increased, and which was very match the theory.(3) Using magnetorheological elastomer to development buffers, analyzed its operating modes: tensile and shear mode. According to the core material properties to propose design principle for the magnetic circuit of buffer, designed the ring and sandwich buffers, and compared the two buffers.(4) Put forward test methods of the two buffers, and structured corresponding test system; Vibration experiment is done against the frequency 200HZ~600HZ with ring buffer, its damping properties get better with the current and frequency increased. The ratio of the excitation acceleration signal and response acceleration signal can arrive 0.321; for the sandwich buffer, the experiments are under the conditions of low-frequency and high-frequency vibrations. In meeting the relations between damping performance and vibration frequencies and current, also found against the sandwich magnetorheological elastomer buffers, its initial low-frequency damping frequency threshold is 40HZ~50HZ and its high-frequency completely damping threshold frequency is 200HZ.(5) Proposed the testing method and testing system for landing buffering experimental; 10cm and 4cm drop experiment are imposed, the maximum response acceleration signal significantly get lower by the excitation current increase, which note that the buffer is effective and controllable in the actual landing buffering. The ratio of respond to the maximum response acceleration signal and the maximum impact acceleration signal can arrive 0.191 when fell from 4cm height; Changed the experimental data to shock response spectrum, also consulted that the shock response spectrum of response signal get smaller with the current increasing, and dropped from 4cm height, its maximum shock spectrum decreases 81% compared to the height of 10cm.