Structure Strength Assessment And Local Vibration Analysis Of Air Cushion Vehicle

Air-cushion vehicle, equipped with fast speed and amphibious attribute, is widely used in the military and civilian shipping field for the past few years due to its adaptation in surface navigation as well as road navigation by virtue of the aprons structure which can help the hull out of wall. Considering the current situation of domestic air-cushion vehicles, mature air-cushion vehicle loading prediction and assessment specification for structural strength have not come up yet. Furthermore,since most research scholars are mainly engaged in analyzing air-cushion vehicle movement, relevant detailed studies in hull general strength and hull vibration are in great shortage. Based on the background above, this thesis mainly focus on air-cushion vehicle's structural strength of the hull under a typical working condition and the hull's local structural vibration response. The contents are presented as follows.(1) Research on the typical hull structures of air-cushion vehicles and relevant structural features.(2) According to Rules for Construction and Classification of Sea-going High Speed Craft published by CCS and air-cushion vehicle modal loading test, studying the determination of air-cushion vehicle's wave load design value under drainage condition and determining external force under lifting and landing condition.(3) Calculating and analyzing whole ship's finite element by adopting direct calculation method for ship strength; obtaining longitudinal strength, transverse strength, torsional strength and shear strength under pad lifting, drainage and landing conditions; gaining hulls'structural stress under different working conditions and hull deformation value as well.(4) Assessing the vibration strength of air-cushion vehicle's local structure; calculating natural frequency values in main cabin, paddle tower and nacelle cabin where vibration problems are quite critical; in the light of General Rules for Ships, for structures which cannot meet the frequency reserve, calculating their vibration response under corresponding excitation source and strengthening or improving the relevant structures if the structures fail to meet the requirement of vibration response.