Thermal Analyses for Induction Sintering of Powder Metal Compacts up to Sintering Temperature

Induction sintering is developed as an alternative method to conventional sintering in order to sinter iron-based powder metal (PM) compacts. In this study, the 12 kW power and 30 kHz frequency induction-sintering machine is used for 3 wt.% copper-mixed iron. The effects of different shapes and sizes of the induction coil, and temperature differences on the PM compacts up to sintering temperature are investigated; these parameters are determined both theoretically and experimentally during induction sintering. Iron-based PM compacts are sintered at 1120°C. Induction sintering of iron-based PM compacts are simulated using a program to examine the effects of magnetic flux and temperature distribution in the sample over time. The results are compared with the experimental studies.Индукционное спекание было разработано как альтернатива обычному спеканию, чтобы спекать прессовки порошковых материалов (ПМ) на основе железа. В данной работе использована индукционная агломерационная машина мощностью 12 кВт и частотой 30 кГц для спекания смеси железа с 3 масс.% меди. Исследованы влияния различных форм и размеров индукционных катушек, разниц температур на брикеты ПМ вплоть до температуры спекания; эти параметры были исследованы как теоретически, так и экспериментально во время индукционного спекания. Брикеты ПМ на основе железа спекались при 1120°C. Индукционное спекание брикетов ПМ на основе железа также смоделировано с использованием программы, которая исследует влияние магнитного потока и распределения температуры в образце со временем. Результаты сопоставлены с результатами экспериментальных исследований.Індукційне спікання було розроблено як альтернатива звичайному спіканню, щоб спікати брикети порошкових матеріялів (ПМ) на основі заліза. В даній роботі використано індукційну аґломераційну машину потужністю у 12 кВт і частотою у 30кГц для спікання суміші заліза з 3 ваг.% міді. Досліджено впливи різних форм і розмірів індукційної шпулі, ріжниць температур на брикети ПМ аж до температури спікання; ті параметри було досліджено як теоретично, так й експериментально під час індукційного спікання. Брикети ПМ на основі заліза спікалися при 1120°C. Індукційне спікання брикетів ПМ на основі заліза також модельовано з використанням програми, яка досліджує впливи магнетного потоку та розподілу температури у зразку з часом. Результати порівняно з результатами експериментальних досліджень

Experimental and numerical studies on improvement of heat transfer of OLED TVs [OLED TV’lerin ısı transferinin iyileştirilmesi üzerine deneysel ve nümerik çalışmalar]

In this study, the thermal behaviors of organic light emitting diodes (OLED) televisions are investigated experimentally and numerically. Organic light emitting diodes are very sensitive to temperature. For this reason, the heat emitted from the diodes must be removed quickly from the environment. The study consists of two parts. In the first part, the use of an effective heat spreader between the screen and the metal casing is proposed as a mechanism for improving the temperature distributions for heat transfer. Pyrolytic graphite plate and tempered pyrolytic graphite plate were used as heat spreader. The graphical heat transfer coefficients of the graphite plates are considerably higher than in the normal direction. The effectiveness of these proposed mechanisms is demonstrated by simulation. As an example model, OLED TV was selected in 15 "dimensions and both experimental and numerical thermal analyzes were performed. The temperature distributions of the OLED were obtained with the help of the ANSYS ICEPAK program, a commercial code that uses the finite volume method. Simulation and test results are obtained very close to each other. The thermal management contributions of OLED TVs using different thicknesses of pyrolytic and tempered pyrolytic graphite plates are presented experimentally and numerically. In the second part, a dual action piezo fan design is proposed. The design parameters of the piezo fan were determined and the numerical analyzes for these parameters were made with the Comsol Multiphysics program. Experimental measurements were made for design dimensions determined by numerical analysis. The result is that the use of a dual-acting piezo provides more efficient cooling than the existing synthetic jets. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.3130324This study supported by TÜBİTAK (Project number: 3130324) and Vestel Electronics R&D Dept. -

Experimental and numerical studies on improvement of heat transfer of OLED TVs [OLED TV’lerin ısı transferinin iyileştirilmesi üzerine deneysel ve nümerik çalışmalar]

In this study, the thermal behaviors of organic light emitting diodes (OLED) televisions are investigated experimentally and numerically. Organic light emitting diodes are very sensitive to temperature. For this reason, the heat emitted from the diodes must be removed quickly from the environment. The study consists of two parts. In the first part, the use of an effective heat spreader between the screen and the metal casing is proposed as a mechanism for improving the temperature distributions for heat transfer. Pyrolytic graphite plate and tempered pyrolytic graphite plate were used as heat spreader. The graphical heat transfer coefficients of the graphite plates are considerably higher than in the normal direction. The effectiveness of these proposed mechanisms is demonstrated by simulation. As an example model, OLED TV was selected in 15 "dimensions and both experimental and numerical thermal analyzes were performed. The temperature distributions of the OLED were obtained with the help of the ANSYS ICEPAK program, a commercial code that uses the finite volume method. Simulation and test results are obtained very close to each other. The thermal management contributions of OLED TVs using different thicknesses of pyrolytic and tempered pyrolytic graphite plates are presented experimentally and numerically. In the second part, a dual action piezo fan design is proposed. The design parameters of the piezo fan were determined and the numerical analyzes for these parameters were made with the Comsol Multiphysics program. Experimental measurements were made for design dimensions determined by numerical analysis. The result is that the use of a dual-acting piezo provides more efficient cooling than the existing synthetic jets. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved

Numerical analysis of vibrating touch screen actuated by piezo elements

Audiovisual feedback generally is used on touch screens on portable electronic devices, which are frequently used in daily life. Tactile feedback is one of the issues that have recently gained importance in this technology. Tactile feedback occurs by stimulating the nerves at the fingertip by moving the touch screen. In this study, we have determined the vibration characteristics of touchscreens made from different materials used in the sector. The finite element method is employed to obtain the vibration modes of the screen. In addition to, the effects of the materials of piezo, applied voltage, the number of the piezo patches are investigated to produce the best vibration function and graphically are presented. © 2017 IEEE

An experimental study of a piezoelectrically actuated touch screen

An audiovisual feedback is used on touch screens in portable electronic devices. When these devices are used in noisy and distracting environments, suitable available feedback methods is severely inadequate and the availability of the device severely reduced. For these reasons, touch screen technology has become a popular recently. These panels used in many sectors such as watches, cars, mobile devices, aerospace. Touch screens, which provide tactile feedback to the user, are activated using solenoid actuators, coil-type actuators or vibration motors. The use of evolving piezoelectric vibrators has attracted considerable attention in recent years to obtain high-resolution tactile feedback. Their higher bandwidth helps create more user-perceivable haptic effects. In this work, we experimented to observe the effect of the piezo vibrator on the screen. As a result, the various types of tactile feedback functions will be developed on the screen and compared. The best vibration functions depending on the settings are obtained through experiments. © 2017 IEEE

Passive thermal management of an OLED TV display

In this study, passive thermal management of a 15’’ OLED TV display is studied. In addition to the OLED display, the effect of other heat generating electronic components on the device is taken into account. Experimental temperature measurements are conducted on the OLED display. The CFD model of the device is developed in order to be able to predict the temperatures and validated with experimental results. A good agreement is obtained between CFD simulation and experimental measurements. To eliminate hot spots and homogenize the tem perature distribution, heat spreaders like copper and graphite are used and the effects of them are discussed in detail. © 2018, National Institute of Optoelectronics. All rights reserved