Analysis of loads on sea wall with SPH

Diplomsko delo predstavlja teoretične osnove metode SPH in program DualSPHysics. Prvotni namen dela je poiskati napake omenjenega programa in metode SPH na primeru z valovi obremenjenega navpičnega zidu (valobrana). Rezultate smo primerjali s Sainflouvovo metodo določanja obremenitve valobrana. Iz teh je razvidno, da vsebujejo veliko šuma, zato je potrebno signal obremenitve filtrirati. Po obdelavi rezultatov se je izkazalo, da so ti zelo podobni teoretičnim rešitvam. Odstopanja med eksperimentalnimi in teoretičnimi vrednostmi so posledica negativnega tlaka, ki se pojavlja v izračunih.The aim of this work is to present the basics of the Smooth Particle Hydrodynamics (SPH) methode and the programme DualSPHysics. The main purpose is to find the flaws of the mentioned programme and methode in case of wave impact on the sea wall. Results have been compared with theoretical loads, calculated with Sainflou theory. Numerical results contain high frequency noise, which was filtered out using low-pass filter. After filtering out the noise, the results were very similar. Deviations between experimental and theoretical values can be explained as the consequence of negative pressure, which occures in numerical calculations

Characterization of complex elasticity modulus of viscoelastic material based on the dynamic response of the plate

Pogostost uporabe polimernih materialov v zahtevnih inženirskih aplikacijah se povečuje z boljšim razumevanjem njihovih temperaturno in časovno odvisnih materialnih lastnosti. Dinamske lastnosti polimerov popisuje kompleksni modul, ki se ga določi z metodo dinamske mehanske analize DMA (ang. Dynamic Mechanical Analysis). Glavna pomanjkljivost te analize je način vpetja vzorca, saj je togost vpetja odvisna od temperature, pri kateri se izvaja meritev. V sklopu magistrskega dela je bil zasnovan nov postopek določanja dinamskih lastnosti, pri katerem je vzorec prosto vpet. Vzorec predstavlja plošča, ki jo dinamsko vzbujamo brezkontaktno preko permanentnega magneta in tuljave, njen odziv pa merimo z laserskim vibrometrom. Na podlagi frekvenčnih prenosnih funkcij nato preko ekvivalentnega numeričnega modela s posodabljanjem določimo kompleksni modul. Meritve so bile opravljene pri več temperaturah. Rezultati nove metode so primerljivi z rezultati DMA analize.The usage of polymer materials for demanding engineering applications is increasing due to better understanding of their temperature- and time-dependant properties. Dynamic properties of polymers known as complex modulus is measured with Dynamic Mechanical Analysis (DMA). The main disadvantage of this method is fixation of the sample, since its stiffness strongly depends on temperature during the measurement. The aim of this master thesis is development of new method for measurements of dynamic properties based on free-free supported sample. The sample is polyamide plate, which is dynamically excited with contactless method using interaction of permanent magnet secured to the plate and a coil. The response of the plate is measured with laser vibrometer. Parameters of measured frequency response functions are used as input parameters of equivalent numerical model. The complex modulus is determined by updating its value untill permissible error between measurement and numerical model is reached. The measurements were carried out at the different temperatures and the results are comparable to the one of standard DMA