Wyniki wyszukiwania - BazTech

1

Fatigue Strength of Thin-Walled Rectangular Elements in the State of Post-Critical Deformation

Mazurek Przemysław

Advances in Science and Technology. Research Journal

|

2019

|

Vol. 13, no 2

84--91

EN

The paper presents the results of numerical analyses and static experimental testing of thin-walled rectangular elements subject to post-critical deformation under shear conditions. The deliberations concerned the elements made of aluminium alloy and the model material. The obtained stress distribution was used to conduct a numerical simulation of the fatigue strength for a metal plate and testing under cyclic load conditions for both types of models.

2

Thermal and mechanical fatigue tests of soldered SMT attachments

Drozd Z., Bronowski J., Drozd J., Szwech M.

Elektronika : konstrukcje, technologie, zastosowania

|

2004

|

Vol. 45, nr 8-9

213-215

EN

One of the most important conditions for implementation of the RoHS directive of European Community is the warranty of good quality and reliability of electrical joints executed in new, environment - friendly technology. Especially for small electronic enterprises it is difficult to prove that the product reliability is not lower than before the change. One of the solutions is application of appropriate accelerated test methods. Typical tests applied in Warsaw University of Technology for reliability assessment of solder joints are investigations of mechanical static strength as function of temperature and fatigue strength in cycling processes. For investigation of fatigue strength are applied different accelerating factors (temperature changes and thermal shocks, cycling of electrical charge and mechanical cycling). The principles of these tests and appropriate test stands will be presented.

PL

Jednym z najważniejszych warunków dla wdrożenia dyrektywy RoHS Wspólnoty Europejskiej jest zapewnienie dobrej jakości i niezawodności połączeń elektrycznych wykonanych według nowej, przyjaznej dla środowiska technologii. Zwłaszcza dla małych i średnich przedsiębiorstw problemem jest wykazanie, że niezawodność wyrobu nie jest gorsza niż przed zmianą. Jednym z rozwiązań jest zastosowanie odpowiednich przyspieszonych metod kontroli. Typowymi próbami stosowanymi na Politechnice Warszawskiej dla oceny niezawodności połączeń lutowanych są badania wytrzymałości mechanicznej statycznej na ścinanie w funkcji temperatury oraz wytrzymałość zmęczeniowa w procesach cyklicznych. Dla badania wytrzymałości zmęczeniowej są stosowane różne czynniki przyspieszające (zmiany temperatury i szoki termiczne, cykliczne obciążenia elektryczne i cykliczne obciążenia mechaniczne). W referacie będą przedstawione zasady tych badań oraz odpowiednie stanowiska badawcze.

3

Wpływ temperatury na trwałość zmęczeniową połączeń taśm przenośnikowych

Błażej R., Hardygóra M., Komander H.

Górnictwo Odkrywkowe

|

2003

|

R. 45, nr 4-5

67-71

PL

W referacie przedstawiono metodę badań zmęczeniowych próbek połączeń wieloprzekładkowych taśm przenośnikowych oraz wyniki badań czterech rodzajów połączeń na podstawie których określono zależność trwałości zmęczeniowej od temperatury próbek i wydłużalności materiałów przekładek oraz gumy klejowej.

EN

A method of fatigue testing multiply conveyor belt splice specimens in the Mini Bionix pulsar with the simultaneous measurement of their temperature by means of the Flir 575 thermovision camera is presented. Four kinds of splices obtained by combining two types of belt (1000 kN/m) and two types of rubber mix tested. Under prescribed load conditions the rise in the temperature of the specimens was observed. Then cooling (by blowing in air) to maintain the specimens' temperature at a constant level was employed. The investigations have shown a significant effect of the belt splices' temperature on their fatigue life. Under the test conditions a gradual increase in temperature by a few degrees would result in a significant reduction in the number of fatigue stress cycles causing splice failure.It has been determined that the fatigue life of the tested belt specimens depends mainly on the extensibility of both piles and the rubber used for splicing. The relationship between fatigue life Z, measured in the number of fatigue stress cycles (thousands of cycles), and the product of extensibilities N (in %) of the materials used to make a splice is expressed as Z-84000N-1.28.It has been determined that the effect of temperature on the fatigue life of the splices also depends on the extensibility of both the plies and the rubber. This dependence is expressed by coefficient tg alpha, where tg alpha=delta Z / delta T = 48500N-2.1. Consequently, the durability of splices made from materials with extensibility decreases much more under increasing temperature than that of splices made from highly extensible materials. This detracts much from the advantages of splices made from materials characterized by low extensibility. To ensure that the results of the fatigue testing of different kinds of conveyor belt splices are reliable and comparable, the temperature of all the tested specimens should be monitored and kept at the same level. It is recommended that the temperature be within a normal temperature range of 23degreee +- 2degree. When assessing the suitability of splices, one should also take into account the effect of elevated temperature and coefficient tga (expressed by cycles difference to temperature difference ration deltaZ / delta T on their durability.

4

Investigations into the operation life for the PW-5 world class glider

Rodzewicz M., Przekop A.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

|

2001

|

nr 12

63-68

EN

The paper presents the research into determining of operation life of the PW-5 World Class Glider. The investigations were conducted at the following two stages: a/ recording of the loads acting upon the glider in the air and estimation of the load spectrum, b/ modeling of the loads on an experimental stand for glider's main structure fatigue test The loads acting upon the glider were recorded on the PW-5 glider equipped with a digital recorder and deflection-sensor of the wing-spar root structure and electronic accelerometer fixed at the glider center of gravity. The load spectrum - was obtained using unique data-processing system described briefly in the paper. It was applied to the fatigue tests on the wing-fuselage-set. The paper presents also the description of the unique resonance method based on electrodynamic impulses.