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In this study, the magnetostrictive properties of grain-oriented electrical steel (GOES) are evaluated and their effect on the model transformers' core noise is presented. One main source of a power transformer's (PT) no-load noise is the magnetostrictive vibration of the magnetic core built with stacked GOES sheets. With an in-house coil measurement system (CMS), the magnetostrictive properties of...
Vibration-induced solder joint fatigue is a main reliability concern for aerospace and military industries whose electronic equipment used in the field is required to remain functional under harsh loadings. Due to the RoHS directive which eventually will prevent lead from being utilized in electronic systems, there is a need for a better understanding of lead-free mechanical behavior under vibration...
With the development of lead-free in electronic products, mixed soldering of lead-free component with lead solder is inevitable in high reliability electronic assembly. For the mixed assemblies, the primary task is to ensure the reliability of mixed solder joints. This study is aimed at finding out the harmonic vibration fatigue properties of plastic ball grid array (PBGA) mixed solder joints under...
With the development of lead-free in electronic products, mixed soldering of lead-free component with lead solder is inevitable in high reliability electronic assembly. For the mixed assemblies, the primary task is to ensure the reliability of mixed solder joints. This study is aimed at finding out the harmonic vibration fatigue properties of plastic ball grid array (PBGA) mixed solder joints under...
A wind-solar hybrid street lamp of a Chinese airport was modeled using Finite element analysis, based on the software platform of ANSYS Workbench 12.1. Its static analysis, buckling characteristic analysis, modal analysis and harmonic response analysis are conducted in this paper. The maximum deformation and stress of a street light was obtained through static analysis under complex loading conditions...
Board level package reliability under mechanical shock has always been a great concern for mobile electronic products. As a result of “short to market” demand for new electronic products, a great effort has always been made towards developing more efficient methods for reliability assessments. This paper presents a board level mechanical reliability test method based on harmonic vibration. Numerical...
This study focuses on assessing the effects of temperature on vibration durability of SAC305 PWAs under random vibration excitation on a repetitive shock (RS) shaker. Major complexities involved in quantifying random vibration response and durability data are first discussed through a comparison of specimen unimodal response under harmonic excitation versus multimodal response to random excitation...
As a newly lighting source, high power white light emitting diodes (LEDs) have many excellent performances and begin to be widely used. The LED street light fixture is one of the most typical and popular applications, which is studied and developed worldwide. However, those studies mainly focused on its light efficiency, light pattern, color temperature, and so on, few concentrated on the reliability...
In this paper, we show experimental results indicating that tactile mechanoreceptors have non-linear sensitivity to an applied vibration. We focus on the perceptual characteristic of high frequency amplitude-modulated (AM) vibration. It is known that humans can feel AM vibration even when its carrier frequency is higher than the perceivable range. Non-linearity of perception should be taken into consideration...
In this paper, the vibration durability of SAC305 solder interconnects of Heat-sink Very-thin Quad Flat-pack No-leads (HVQFN) assemblies is investigated by accelerated stress testing and Physics-of-Failure (PoF) simulations, under various types of vibration excitation. In future work, these results will be used to develop PoF models for vibration fatigue durability of Pb-free SAC305 solder interconnects...
Based on finite element method and ANSYS software, vibration feeder is fatigue break influenced by exciting force alternate load. This paper introduces the rational finite element model of vibration feeder. It discusses harmonic response analysis and discovers weak links which is angle steel junction of side plate, feed inlet and junction panel between no feed side plate and bottom plate then makes...
We derive in this paper equations of motion of board-level IC packages subjected to swept sine vibration loads following the support excitation scheme. Harmonic analysis is performed based on the argument such that at each loading state over the swept sine process, hysteresis responses of solder joints following the isotropic hardening rule vanish fairly quickly so that plasticity is fully developed...
This paper presents a preliminary study of the chaotic behavior of servo-flap mid-span bending of a four-blade helicopter during hover, low and high-speed forward flights. The servo-flap vibratory measurement was used to create state vectors in a multidimensional space through time-delay embedding, and the trajectory of state vectors in the reconstruction state space was quantified using the correlation...
Decreasing the length of thermoelectric (TE) module legs results in a significant increase in power density, both for cooling applications and electricity generation. However, this reduction also results in a significant increase of mechanical stress in the legs materials. Thus, it is important to implement an effective method to characterize the mechanical properties, such as mechanical spectroscopy,...
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