水下爆炸条件下自由场压力载荷时频特征分析

在舰船结构水下爆炸试验中,为了研究水下爆炸条件下水中自由场压力载荷的时频特征,针对某水下爆炸试验自由场压力测试试验数据,基于小波分析对信号进行时频特性分析,得到水中自由场压力信号的时频分布和能量分布状况。分析结果表明:针对水下爆炸自由场压力载荷,基于小波分析技术对其时频特征进行分析,可得到水下爆炸自由场压力载荷所包含的频率信息、强度信息以及不同频段下的载荷持续作用时间等信息;另外,可对冲击波、滞后流和二次压力波这3个不同信号阶段进行频段与能量统计分析;在不同频段上对冲南击信号的能量进行统计发现,冲击波阶段在8 kHz以下频段集中了超过90%的能量,其中4 kHz以下频段的能量最大,在滞后流和二次压力波阶段,需特别重视250 Hz以下的低频段对船体结构及设备的影响,该结果对舰船结构及设备的抗冲击防护具有借鉴意义。

Time-frequency characteristics analysis of free-field pressure with underwater explosion

To obtain the characteristics of the free-field pressure with underwater explosion, the time-frequency characteristics of the monitored free-field pressure signals are studied through wavelet analysis, based on the experimental free-field pressure data subjected to underwater explosion.By using these signals, the pressure-time curves and the energy distributions in different blasting frequency bands are obtained.The result shows that the obtained time-frequency characteristics of free-field pressure can be used to generate the shock wave signal, the after flow signal, and the second pressure pulse, and by analyzing the energy and frequency component, it is easy to get the detailed time-frequency information of the free-field pressure signal intensity, frequency and duration.More than 90% of the energy of the shock wave pressure signals condenses in the band lower than 8 kHz, and the highest level of energy appears below the frequency of 4 kHz, and special attention should be directed to the low frequency band below 250 Hz of the after flow signal as well as the second pressure pulse for ship structure and equipment.Overall, this paper provides reference for shock-resistance analysis of the ship structure.