|
| |
|
| |
|
| |
|
|
The effect of chemical degradation of surface layers on mechanical properties of wood
Drdácký, Miloš ; Kloiber, Michal ; Frankl, Jiří ; Bryscejn, Jan ; Tippner, J.
The aim of the research was the determination of the effect of chemical degradation on the surface layers of wooden constructional elements and their mechanical properties and also the depth which the damage reaches. The degradation of wood surface layers was caused by chemical reactions of some compounds contained within fire-prevention coatings applied repeatedly on wooden constructions of historic buildings in the past. These include e.g. ammonium sulphate and ammonium phosphate. This paper presents experimental procedures and results obtained through measuring of mechanical properties in the damaged layer of fibrillated wood and in wood without damage. The observed properties were wood compressive and tensile strength and wood hardness. The results proved a loss in cohesion and changes in mechanical properties only in a thin surface layer.
|
|
| |
|
| |
|
| |
|
|
Properties of bulk nanostructured Al-based alloy at cyclic loading
Chlupová, Alice ; Chlup, Zdeněk
Al-based alloy having a nominal chemical composition of Al93Fe3Cr2Ti2 (at.%) is highly promising structural material due to advantageous weight-strength ratio and in comparison with commercially used Al alloys also good thermal stability because of presence of reinforcing icosahedral quaiscrystals in the structure. In the present work the mechanical properties and especially fatigue behaviour of this type of nanoquazicrystalline material obtained in bulk form are described. For cyclic loading the cylindrical specimens were machined from two types of extrudates with different powder particle size (PPS). Fatigue properties were studied using servohydraulic MTS machine and cyclic loading was performed at constant stress amplitude with positive mean stress. Measured stress-strain data were evaluated and fatigue life in form of S-N curves was obtained. Fracture surface of broken testpieces was observed, fractographic analysis was performed and fracture mechanism was evaluated.
|
|
| |
|
| |
guest ::
