RAZISKAVA SELEKTIVNIH PROSTORSKIH STRUKTUR IN RAZVOJ ANALITIČNEGA MODELA LAHKIH NOSILCEV

Sever, Peter

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Title:	RAZISKAVA SELEKTIVNIH PROSTORSKIH STRUKTUR IN RAZVOJ ANALITIČNEGA MODELA LAHKIH NOSILCEV
Authors:	ID Sever, Peter (Author) ID Drstvenšek, Igor (Mentor) More about this mentor... ID Gotlih, Karl (Comentor)
Files:	DR_Sever_Peter_2014.pdf (3,65 MB) MD5: E4D3E13931B8531BA7B640B2941543D0
Language:	Slovenian
Work type:	Dissertation
Typology:	2.08 - Doctoral Dissertation
Organization:	FS - Faculty of Mechanical Engineering
Abstract:	Predložena doktorska disertacija obravnava aktualno področje slojevitih tehnologij, s poudarkom na tehnologiji selektivnega laserskega sintranja. Selektivne prostorske strukture predstavljajo inovativni koncept generiranja lahkih izdelkov, ki z odprto-celično ali zaprto- celično strukturo izkoriščajo potencial ponujene geometrijske svobode V okviru izvajanja eksperimenta je bilo določeno izvedljivo območje premerov nosilcev prostorskih struktur, ki so omejene med 3-kratnik in 8-kratnik nazivnega premera laserskega žarka. Uvodne meritve na epruvetah z masivno strukturo in na epruvetah z izdelano prostorsko strukturo so izkazale izrazito tehnološko anizotropijo, kjer je razvidna razlika med natezno trdnostjo epruvet izdelanih v Z smeri in trdnostmi epruvet izdelanih v X in Y smeri. Analiza prelomnih mest epruvet je razkrila, da je vzrok za identificirano tehnološko anizotropijo predvsem v nepopolnih spojih med posameznimi izdelavnimi plastmi v smeri izdelave oziroma rasti izdelka, ki so, kot ugotovljeno na podlagi izvedenih simulacij z metodo končnih elementov, predvsem posledica premajhnih vnosov energije. Segmentacija epruvete na osrednji in vprijemni del je omogočila tehnološko vzdržen selektivni vnos energije, kjer so bile poprej uporabljene epruvete vnovič izdelane s povišanim vnosom energije v osrednjem delu z izdelano prostorsko strukturo. Ponovitev meritev nateznih trdnosti je potrdila, da lahko zaradi intenzivnejšega hlajenja selektivnih prostorskih struktur, ki so v procesu izdelave obdane z izdelavnim materialom v praškasti obliki, že zgolj s spremembo vnosa energije bistveno prispevamo k izboljšavi vezi med posameznimi sloji, s čimer minimiziramo tehnološko anizotropijo. Alternativno, je na nivoju izdelka s podrejeno oblikovano osnovno celico v eksperimentu prikazana rešitev, ki v funkciji osnovnega gradnika prostorske strukture z inverzno anizotropnimi lastnostmi izniči vpliv tehnoloških parametrov in tehnološko anizotropijo. Minimizirana in v nekaterih primerih celo izničena tehnološka anizotropija, je v okviru naloge omogočila oblikovanje analitičnega modela za napovedovanje nateznih napetosti v odvisnosti od raztezka, ki potrjuje zadano tezo in predstavlja končni rezultat te doktorske disertacije.
Keywords:	selektivno lasersko sintranje, selektivne prostorske strukture, selektivni vnos energije, lahki nosilci, tehnološka anizotropija
Place of publishing:	[Maribor
Publisher:	P. Sever]
Year of publishing:	2013
PID:	20.500.12556/DKUM-43097
UDC:	620.16:621.767(043.3)
COBISS.SI-ID:	271832576
NUK URN:	URN:SI:UM:DK:RPT5NLXI
Publication date in DKUM:	04.02.2014
Views:	2769
Downloads:	163
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Categories:	KTFMB - FS
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Secondary language

Language:	English
Title:	RESEARCH ON SELECTIVE STRUCTURES AND DEVELOPMENT OF ITS ANALYTICAL MODEL
Abstract:	Submitted thesis deals with the area of layered technologies, with an emphasis on technology of selective laser sintering. Selective space structures represent an innovative concept for generating lightweight products with open-cell or closed-cell structure, exploiting the potential of geometrical freedom of layered technologies. In the context of the implementation of the experiment, the feasible diameter range of space structures beams was determined, which were limited between 3 times and 8 times diameter in relation to the nominal diameter of the laser beam. Preliminary measurements of the samples with a solid structure and the samples produced with integrated space structure have demonstrated strong technological anisotropy, which clearly shows the difference between the tensile strength of the samples manufactured in the Z direction and strength of samples manufactured in X and Y directions. Analysis of samples crack areas has revealed, that the cause of the identified technology anisotropy mainly lies in an incomplete connections between the individual layers in the direction of the growth of the product, mainly due to lack of energy density inputs, as determined on the basis of simulations carried out with the finite element method. Segmentation of the specimen on the central area part and to the engagement area part has allowed and enabled the sustainable selective energy density inputs for producing the samples with higher inputs of energy in the central part with integrated space structure. Final measurements of a tensile strength on the samples manufactured with higher energy density inputs has confirmed, that the intensive cooling of selective spatial structures, enables a higher energy inputs, which significantly contributes to the improvement of bond quality between the individual layers, thus minimizing the technological anisotropy. Alternatively, within finite element method the unit cell with optimized topology has been developed, which has confirmed, that the technological parameters influence and technological anisotropy can be minimized due to the optimized topology of unit cell with inverse anisotropic mechanical properties. Furthermore, minimized and in some cases even eliminated technological anisotropy has enabled the design of an analytical model to predict the tensile stress in relation to the strain, thus confirming stated thesis as the final result of this dissertation.
Keywords:	selective laser sintering, selective space structures, selective energy density inputs, lightweight beams, technological anisotropy

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