At the final step of the injection process (of a plastic product with cavities) when the part is on the point to be ejected the adhesion phenomena occurs between the core and the plastic part. The mold adhesion effect has a significant influence on the mold design ejection system and over the whole process. This paper presents a computation methodology of the demolding moment for two cases of plastic injected parts with internal trapezoidal thread. Knowing the value of this moment offer us the possibility to adopt the right design solution of the ejector system and of the entire mold. As further work the author will try to validate this method through a set of practical experiments.

The most outstanding parameter that governs the fatigue crack growth under tensile stresses field is the stress intensity factor, mode I, KI. This is a sufficient parameter to describe the whole stress field at the crack tip. An accurate stress intensity factor KI evolution was worked out taking into account the position of the crack centre depth, and also, the residual stresses that act on the surface of the tooth, tensions that are linearly decreasing with the depth in the contact zone. On the other hand, the parameter that governs the crack fatigue growth in the case of compression stresses field is the stress intensity factor mode II, KII. This paper also presents the KII variation along pitch line with respect to the Hertzian contact stresses, the residual stresses and the crack centre depth of an initial crack in the sub-surface of the pinion tooth, having different inclination angle α. As result of this study, some particular factors favorable to the propagation of the fatigue cracks towards the surface of the gear tooth were identified. The availability of a master curve for a particular material relating fatigue crack growth rate and range of stress intensity factor enables a designer to predict growth rates for any cracked body, and it is not limited to situations similar to those pertaining to the cracked stressed specimen used to generate the original data.

MEMS resonator represents currently one of the important research areas of Microelectromechanical Systems (MEMS). The usual applications of MEMS resonators are the radio-frequency electromechanical devices, MEMS gyroscopes and resonant sensors. The main part of a MEMS resonator is the mechanical vibrating structure that can be fabricated as microcantilevers, microbridges or in a more complex configuration as micromembranes. The scope of this paper is to investigate the dynamic behavior of an electrostatically actuated MEMS cantilever under different oscillating modes in order to determine the resonant frequency, amplitude and velocity of oscillations. Moreover, based on the resonant frequency experimental curves, the quality factor for different oscillating modes is determined. The effect of operating conditions on the frequency response of investigated microcantilever is monitored. As a consequence, the experimental tests are performed both in ambient conditions and in vacuum. The dynamic response of microcantilever in vacuum is influenced by the intrinsic dissipation energy and the sample behavior in air depends on the intrinsic losses as well as the extrinsic dissipation energy.

This paper presents the results of the interesting experimental research regarding the influence of the additives over a hydraulic oil i.e. HFE46 (produced by ChemTrend [10]). In this vein, were used two types of additives (resulting two variants of oils denoted as sample C and D respectively) and was carried out a gravimetric determination (using the Timken test) analysing the hydraulic oils lubricating proprieties. Also, measurements regarding the vibrations in the tribotechnical system-TTS were conducted.

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