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本文以两端固支梁为模型,用分析和实驗方法討論了梁在自由振动过程中与带間隙的支撑碰撞的动力效应。目的是探討碰撞对梁的振动特性和振动响应的影响。实驗分別用了一个、两个和三个支撑板以及四种不同尺寸的支撑板,支撑板的位置是可調节的,支撑板与梁之間的間隙在0.25～1.00mm范围內改变。主要做了单边碰撞实驗,对双边碰撞实驗做了初步观察。实驗結果表明:梁的基阶振动頻率接近单跨梁的基阶固有頻率,但碰撞作用使基阶振动頻率明显地提高了。碰撞引起了許多高頻成分。最后,以梁中点初位移与間隙尺寸之比为参数給出了基阶頻率的变化曲綫,第一次碰撞开始的时間、第一次碰撞的持續时間的变化曲綫。对測得的位移响应时程曲綫进行了Fourier分析,并給出了离散譜綫。分析給出了中点有一个刚性支撑的碰撞結果,与测量結果符合良好。
In this paper, the two-end fixed beam as a model, with the analysis and experimental methods to discuss the beam in the free vibration process and the gap with the support of the dynamic impact. The purpose is to investigate the impact of the collision on the vibration characteristics and vibration response of the beam. One, two and three support plates and four support plates of different sizes were respectively used in the experiment. The position of the support plate is adjustable, and the gap between the support plate and the beam is changed within the range of 0.25 to 1.00 mm. Mainly made a unilateral collision test, made a preliminary observation of bilateral collision experiments. The experimental results show that the fundamental vibration frequency of the beam is close to the fundamental natural frequency of the single span, but the collision frequency increases the fundamental vibration frequency obviously. The collision caused many high-frequency components. Finally, taking the ratio of the initial displacement and the gap size as a parameter, the change curve of the fundamental frequency, the time of the first collision and the duration of the first collision are given. Fourier analysis of the measured displacement response time history curve is given, and the discrete spectral lines are given. The analysis gives the collision result with a rigid support at the midpoint, which is in good agreement with the measurement results.