宏细观振动对选择性热激励效果的影响

发布时间：2018-11-13 20:47

【摘要】：激振频率是选择性激励红外热成像检测技术的控制参数。从结构共振的角度选取含微裂纹的混凝土简支梁作为激励对象,以简支梁自振频率作为激振频率,测试激励效果;并选用40 k Hz激振频率进行对比试验。试验结果显示,40 k Hz频率激振下的简支梁出现了显著热激励效果,但自振频率未出现激励效果。结合这一试验现象,在机理层面计算分析了简支梁宏观整体振动、梁内细观质点波动两种振动状态对热激励效果的影响以及它们之间的相互作用规律。分析结果表明:在整个激励过程中,结构整体振动的热激励能力弱于质点波动,并持续消弱质点波动的强度;细观质点波动是热激励效果出现的原因,可选用40 k Hz超声频率激振来降低宏观整体振动强度,消除整体振动对质点波动的弱化作用。
[Abstract]:Excitation frequency is the control parameter of selective excitation infrared thermal imaging detection technology. From the point of view of structural resonance, simply supported concrete beams with micro-cracks are selected as excitation objects, the natural vibration frequency of simply supported beams is taken as exciting frequency to test the excitation effect, and the 40 k Hz excitation frequency is chosen to carry out comparative tests. The experimental results show that the simply supported beam excited at 40 k Hz frequency has a remarkable thermal excitation effect, but no excitation effect is found in the natural vibration frequency. Combined with this experimental phenomenon, the macroscopic whole vibration of simply supported beam, the influence of the two vibration states of the mesoscopic particle fluctuation in the beam on the thermal excitation effect and the interaction between them are calculated and analyzed at the mechanism level. The results show that the thermal excitation ability of the whole vibration of the structure is weaker than that of the particle fluctuation in the whole excitation process, and the intensity of the fluctuation of the whole structure is weakened continuously. The microparticle fluctuation is the reason of the thermal excitation effect. The 40 k Hz ultrasonic frequency excitation can be used to reduce the macroscopic whole vibration intensity and eliminate the weakening effect of the whole vibration on the particle fluctuation.
【作者单位】：南京水利科学研究院水文水资源和水利工程科学国家重点实验室;河海大学水利水电学院;镇江市丹徒区航道管理处;
【基金】：国家自然科学基金重大科研仪器研制项目(51527811)
【分类号】：TV698.1

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