Department of Materials Technology and Architectural
Spring june 2006
Creep of Polymers
The aim of this kind of laboratory is always to demonstrate the phenomenon of creep in materials and its effect on the future mechanical functionality of elements.
YOU MUST EXAMINE ASTM COMMON D2990-01 PRIOR TO THE LAB
Most of the elements experience period dependent permanent deformation as a function of your energy at a continuing stress and this phenomenon is referred to as creep. For example , metals and ceramics display creep by high temperatures (> 0. your five Tm, exactly where Tm can be melting temperature), whereas polymers exhibit creep even by room heat. Some gentle and ductile metals including lead undergo creep also at space temperature. Because of creep, the mechanical properties of most from the materials deteriorate over a period of period. Understanding and quantifying slip is important through the point of designing supplies for permanent use. For example , a heavy steam turbine or maybe a gas turbine blade needs to be characterized prior to it is placed into service because so many of this kind of components happen to be subjected to excessive stresses and temperatures on the order of thousands of hours (~10, 000 or 100, 000 hours).
In this laboratory, we will study the creep of any high density polyethylene using a basic creep device (see fig. 1). The sample is loaded in to the right most portion of the lever (for details see Fig. 1) and under the dial signal. Note down the inner indicator (small needle) reading and adjust the outer sign in such a way that that reads zero at the beginning. Gauge the length of the launching points around the lever.
Puppy bone shaped tensile trials will be used pertaining to testing. Several samples will probably be provided per group while each one will be examined at different load.
Gauge the gage length and density and thickness of the gauge section.
Put the specimen in to the apparatus. Apply force in less than a few seconds and note down...
Referrals: 1 . George E. Person, Mechanical metallurgy, McGraw-Hill, next edition, 1976.
2 . Lawrence E. Nielsen and Robert F. Landel, Mechanical homes of polymers and composites, 2nd edition, Marcel Dekker, Inc., year 1994.
3. ASTM standard D2990-01, Standard check method for Tensile, Compressive, and Flexural creep and creep-rupture of Plastic materials.
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