The mechanical properties of the composite materials for prosthetic sockets are a key determinant of the quality and usability of prostheses. Our aim was to compare the existing materials used in ...production at our institution with some modified, potentially improved materials. We conducted an industrial experiment. The existing material (A) was compared with three newly produced materials that introduced changes in the lamination process: B1, where an infusion spiral tube was added; B2, where the resin was degassed; and B3, where a mesh and peel ply were used. The specimens underwent laboratory strength testing. The strength measurements were statistically analysed using one-way analysis of covariance (ANCOVA) that was adjusted for specimen thickness because of the observed negative correlation of thickness with strength. Material A had the highest bending strength, on average, but there were no statistically significant differences in the bending strength between the materials after adjusting for the specimen thickness (p = 0.941). Materials B1 and B2 exhibited statistically significantly lower tensile strengths than material A (p < 0.001). Material B3 had the lowest average tensile strength, but it could not be statistically distinguished from the others, because of the significantly larger average specimen thickness. The compressive strength was tested only for materials B1, B2 and B3; their averages did not differ statistically significantly (p = 0.291). Laboratory strength testing provided important insights into the differences between the various laminated composite prosthetics materials. We did not reach our initial goal to produce a better material, but we will continue our research and development in this field with a more systematic, technological approach.
Layering or lamination of a dough strip is a specific operation that appears in product lines for hard biscuits and crackers, which is different compared to other conditory equipment. This operation ...forms a multilayered structure of the dough that has multiple positive effects to the final product. Thus, the dough strip stresses induced by the strip thinning are soothed, the airy structure, created by the bubbles trapped between adjacent layers, is obtained (increased volume) and the dough layers are blended giving a uniform dough strip. The quality of a laminated dough depends primarily on the quality of the machine – the laminator and its layering device, i.e. reversible mechanism which processes the incoming raw materials (flour, oil, grease, additives), regardless of the quality differences. The aim of this thesis is the creation of such a class and structure of mechanism with integrated drive by a methodological approach that will achieve the required movement and give the well formed layered dough structure. Despite the fact that dough viscosity and adhesiveness can vary, the stacking and folding process must proceed continually with the releasing the induced stresses at the same time. These requirements can be achieved successfully by the synthesized structure and reverse drive mechanism of the new generation. Previous research and studies of the motion, forming and layering of a dough strip do not provide the possibility of direct synthesis of a new solution in terms of optimal synthesis of the structure and drive of the executive mechanisms. In order to find better solutions, it was necessary to apply the tools of modern methods, such as axiomatic design. By the applying the axiomatic design methodology, the technological requirements and the design space of a new solution are defined successfully, clearly, parametric and by the quantifiable criteria. Since this is a field of constructing food - conditory machines, which are explored within the factory development and research centers, a very small number of published VII works, are available. The most important accessible documents are related to the patent solutions. The primary space of the existing solutions is defined here, as well as the free space for the synthesis of a new solution that will not interfere with existing patent requirements. Regard this, by the consideration of implemented solutions for layering device, the research goal was chosen, which realization enables the finding the original solution that would present a technological improvement over the current situation in this technique. There are lines for the production of cookies and crackers on the world market based on the use of different mechanism solutions for the dough strip lamination. Long term study showed that none of these solutions can deliver the high quality product output for the input raw materials which vary in a wide range. In contrast to these known solutions, the newly-designed reversible mechanism for lamination demonstrated exceptional flexibility and applicability for lower quality raw materials. On this way, the wide space for the development, implementation and marketing of this class of layering reversible mechanism is opened. It is concluded that the set of methodologies for the synthesis of optimal structure of the reversible mechanism is founded completely original, the applicable solutions has been developed, 3D model has been defined and virtual functionality verification has been realized, then, the prototype solution is accomplished after original technical documentation, and the complete validity of the solutions is proved by the operational test.
Slojevanje ili laminacija testane trake je jedna specifična operacija koja postoji kod linija za proizvodnju tvrdog keksa i krekera što je drugačije u odnosu na ostalu konditorsku opremu. Tom operacijom formira se višeslojna struktura testa koja ima višestruko pozitivan efekat na krajnji proizvod. Umiruju se naponi u testanoj traci izazvani stanjivanjem trake, dobija se vazdušasta struktura od mehurića zarobljenih između susednih slojeva (povećan volumen) i pretapaju se slojevi testa dajući uniformnu traku. Kvalitet laminiranja testa prvenstveno zavisi od kvaliteta same mašine – laminatora i njenog uređaja za slojevanje, odnosno reverzibilnog mehanizma koji treba da obradi ulazne sirovine (brašno, ulje, masnoća, aditivi), bez obzira na odstupanja njihovog kvaliteta. Cilj ove disertacije je da se metodološkim pristupom kreira takva klasa i struktura mehanizma sa integrisanim pogonom koja će ostvariti zahtevano kretanje, a kao krajnji rezultat dati dobro formiranu, slojevitu testanu traku.Uprkos činjenici da testo može biti promenljivog viskoziteta i adhezivnosti proces kontinualnog slaganja i presavijanja mora kontinualno da se odvija uz istovremeno oslobađanje indukovanih napona. Ovi zahtevi mogu da se ostvare uspešno sintetizovanom strukturom i pogonom reverzibilnog mehanizma nove generacije. Dosadašnja istraživanja i studije o kretanju, oblikovanju i slojevanju testane trake, a sa aspekta optimalne sinteze strukture i pogona izvršnih mehanizama ne pružaju mogućnost neposredne sinteze novog rešenja. Radi pronalaženja kvalitetnijeg rešenja potrebno je bilo primeniti alate savremenih metoda, kao na primer aksiomatsko projektovanje. Primenom metodologije aksiomatskog projektovanja, veoma jasno, parametarski, i kvantifikovanim kriterijumima uspešno se definišu tehnološki zahtevi i projektni prostor novog rešenja. Pošto se radi o oblasti konstruisanja prehrambeno - konditorskih mašina što se istražuje unutar fabričkih razvojno - istraživačkih centara, to je dostupan veoma mali broj publikovanih ostvarenja. Najznačajnija dostupna dokumentacija vezana je za patentna rešenja.Tu je definisan primarni prostor postojećih rešenja i slobodni prostor za sintezu novog rešenja koje neće zadirati u postojeće patentne zahteve. U tom smislu, razmatranjem već primenjenih rešenja uređaja za slojevanje, izabran je cilj istraživanja čijim realizovanjem se omogućava iznalaženje originalnog rešenja koje treba da predstavlja tehnološki napredak u odnosu na postojeće stanje u ovoj tehnici. Na svetskom tržištu postoje linije za proizvodnju keksa i krekera kod kojih se koriste različita rešenja mehanizama za laminaciju testane trake. Višegodišnjim ispitivanjem pokazalo se da nijedno od tih rešenja ne može da da izlazni proizvod visokog kvaliteta za ulazne sirovine koje variraju u širokom dijapazonu. Za razliku od tih poznatih rešenja novokonstruisani reverzibilni mehanizam za laminiranje pokazao je izuzetnu fleksibilnost i primenjivost kod sirovina slabijeg kvaliteta. Tim je otvoren širok prostor za razvoj, primenu i plasman ove klase reverzibilnog mehanizma za slojevanje. Zaključuje se da je potpuno originalno postavljena metodologija za sintezu optimalne strukture reverzibilnog mehanizma, da je razvijeno primenjivo rešenje, da je definisan 3D model i izvršena virtualna verifikacija funkcionalnosti, da je zatim prema originalnoj radioničkoj i sklopnoj dokumentaciji izrađeno prototipsko rešenje i da je kroz operativno ispitivanje dokazana potpuna validnost postavljenog rešenja.
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