Vibration fatigue

About: Vibration fatigue is a research topic. Over the lifetime, 3460 publications have been published within this topic receiving 46297 citations.

A Distinctive Fatigue Failure Criterion

Abstract: This paper presents a new fatigue failure criterion for asphalt paving mixtures that is simple, unique, and distinctive. Bending beam fatigue testing in the controlled strain mode at a 1000microstrain level and 19C temperature was performed on eleven asphalt mixtures that included unmodified and modified binders. Analysis of fatigue load-deformation raw data for each fatigue load cycle was conducted to determine the true point of fatigue failure. With application of a sinusoidal strain on a sample, a sinusoidal response stress is expected even for a heterogeneous material like asphalt concrete. In such a case, a smooth traditional load-deformation (or stress-strain) hysteresis loop is anticipated. This holds true as long as there is no fatigue damage induced in the material. With repeated load applications, the sample starts to fatigue and microcracks are induced. These microcracks introduce discontinuities in the stress paths and the stress response starts to distort. This gets reflected in the load-deformation hysteresis loop, which in turn shows this distortion. Similar distortion can also be seen by observing the sinusoidal load-deformation waveform, where the stress response is no longer dependent on the strain input due to the formation of interconnected fatigue cracks. By tracking the distortion in the hysteresis loop or in the waveform, one is able to get a clear indication of when the first microcracks appeared, and how they progressed up to the point of complete fatigue failure.

Development of BGA solder joint vibration fatigue life prediction model

Abstract: The objective of the present study is to develop a vibration fatigue life prediction model for ball grid array (BGA) solder joint. In this study, 3D global/local finite element models were first constructed with MSC/PATRAN code. For the global model including BGA package soldered onto the printed wiring board (PWB), linear finite element dynamic analyses with an excitation normal to the PWB were conducted using MSC/NASTRAN code to determine the dynamic responses at the two ends of BGA solder joint. In these analyses, a single-degree-of-freedom system was assumed. A steady-state harmonic (or frequency sweep) response provides phase angle values while a random response furnishes the power spectral densities as well as their root mean square (RMS) values. For the local model having a refined mesh to simulate the local region in detail, a linear finite element static analysis was conducted by applying the derived RMS values with their corresponding phase angles to this model (at the two ends of the critical corner solder joint) in order to determine the solder effective stress/strain RMS value. A vibration fatigue life model, evolved from an empirically derived formula of universal slopes based on high-cycle fatigue test data, was established. This model combined with a three-band technique and the derived solder effective strain was then used to predict the BGA solder joint survivability/durability. This prediction will be compared to test results, which will be provided by in-house on-going R&D, to validate the proposed BGA solder joint vibration fatigue life prediction model. An example of a 600-pin plastic BGA soldered onto the various locations of the PWB was illustrated in the present study.