Spiral conveyor

Tato bakalářská práce se zabývá návrhem a konstrukčním řešením spirálního šnekového dopravníku. V textové části je proveden návrhový výpočet hlavních částí spirálního šnekového dopravníku, návrh pohonné jednotky, uložení šnekovnice, pevnostní kontrola funkčních částí a volba vhodného přepravovaného materiálu. Výkresová dokumentace vychází z textové části a skládá se ze sestavného výkresu dopravníku, seznamu položek a výkresu šnekovnice.This bachelor thesis deals with the design and construction design spiral conveyor. In the text part is performed design calculation of the major parts of spiral screw conveyor, drive unit design, storage worm screw, strength check of functional parts and an appropriate choice of material transported. Design documentation based on text part and consists of a conveyor assembly drawing, a list of items and drawing worm screw.

Elastomer testing: The risk of using only uniaxial data for fitting the Mooney-Rivlin hyperelastic-material model

The Mooney-Rivlin constitutive model is often used for the characterization of hyperelastic rubber-like materials. To obtain the material constants for a model, only a uniaxial-tension-data set is usually used. Though it is regularly used for its easiness of processing data in a simple and practical way, the method is considered to be insufficiently accurate. To analyse the shortcoming of the method, a detailed examination was done with the Mooney-Rivlin two-parameter model. This paper discusses the variations related to three basic load curves, i.e., uniaxial, equibiaxial and pure-shear curves. For a visual observation of the fitted-data dispersion, two data-fitting cases were considered. The first one was the data fitting only through uniaxial data while the second one was a combination of uniaxial and pure-shear experimental-data curve fitting. A detailed one-to-one comparison of the curves was done to achieve an accurate estimation of the variations.TBU in Zlin [IGA/FT/2017/002

Applicable FEM models for layered beams

We need to create appropriate and effective numerical (FEM) model to optimize properties of a composite product. The creation and evaluation of an efficient numerical model that could be used for an analysis of layered composite is the aim of this work. The model has to be able to take into account the properties and layout of the individual layers and must allow effective change of these parameters; thickness, material and number of layers especially. Various models of the same product are created and compared. The models differ in the type of used FEM elements. The results of models (deformation primarily) were compared with the result of analytical computation. Further, time and computational requirements of individual models are also evaluated. Element types used for investigated models are: 1D elements, 2D plane stress solid elements, 2D plane strain solid elements and shell elements. Models created form 1D and shell elements showed a close agreement with the analytical solution, and they provide the appropriate tools for the definition of layered structures and for the analysis of results. © 2017

Contact between end coils of cylindrical helical compression springs

Tato diplomová práce se zabývá problematikou šroubových tlačných válcových pružin tvářených za tepla. První část práce je zaměřena na základní popis problematiky a určení potenciálu aktuálního trhu. Teoretická část popisuje vliv kontaktní linie na chování pružiny a porovná ho s normativními předpisy. V další části jsou navrženy postupy pro určení vhodného tvaru šroubovice. Poslední část je věnována praktickému měření, při kterém byla sledována změna tvaru šroubovice při výrobním procesu. Výsledkem je navrhnutí nápravných opatření vedoucí k optimalizaci výroby a dále k ověření MKP modeluThis diploma thesis deals with hot-formed helical compression springs. The first part of the thesis describes related problems and determines market potential. Following theoretical part describes the influence of contact line on behaviour of springs and compares it with normative regulations. Methods suitable for determination of helix shape are covered in the next part. The last part focuses on practical measurement, in which the change of helix shape during manufacture was observed. The main output of this diplomat thesis is suggestion of measures that should contribute to both optimization of manufacture and verification of FEM model.

Calculation of the tyre curing mould cavity shape using FEM

This paper describes a modelling methodology that predicts a contour of a pneumatic tyre in the curing mould. Tyre contour is designed to be in the equilibrium shape. Such shape is described by a system of complex mathematical equations that has to be solved numerically. In this new approach a standard FEM software is employed to gain the shape without the need of dealing with these equations manually. The quality of the proposal of FEM approach was assessed by comparing the meridian to a verified solution for several tyre constructions and sizes. Selected results are presented to show the accuracy of the FE modelling procedure. Nowadays, most of the produced tyres are of a radial construction. Therefore, this paper deals only with radial tyres. © 2017

Hyperelastic material characterization: A method of reducing the error of using only uniaxial data for fitting mooney-rivlin curve

The risk of error in using only uniaxial data for fitting constitutive model curves is emphasized by many hyperelastic material researchers over the years. Unfortunately, despite these indications, often the method is utilized in finding material constants for mathematical models. The reason behind this erroneous practice is the difficulty in obtaining biaxial data. Therefore, as a remedial measure, in this research work we suggest a method of forecasting biaxial data from uniaxial data with a reasonable accuracy. Initially, a set of data is collected through standard uniaxial test. A predefined generalized function is then used to generate a set of values which subsequently used as multiplication factors in order to get biaxial tension data. Eventually, with availability of two data sets, Mooney-Rivlin two parameter model was used for combined data fitting. Material constants were then obtained through least squares approach and thereby theoretical load curves namely uniaxial, equi-biaxial tension and pure shear were drawn. The results of this work suggest a definite improvement related to three curves when compared with only uniaxial test data fitted outcomes. For validation of secondary biaxial data, separate eqi-biaxial test was done and resulting curves were compared. Biaxial primary data curve and forecasted data driven curve show identical data distribution pattern though there is a shift and therefore provide a basis for further research in this direction. © 2018 Trans Tech Publications, Switzerland

The numerical analysis of axially loaded elastomeric bushing

Mechanical behavior of a rubber bushing of a stabilizer of a passenger car is studied in this article. An analysis of behavior of the bushing loaded in the axial direction is performed. An identification of the critical points in the bushing body and, especially, in the interface between the bushing and the stabilizer bar for later optimization of the whole system of the stabilizer fixing in the car construction is the aim of this work. An advanced FEM system including such effects as a strongly nonlinear strain/stress relation of material of the bushing (hyperelasticity), large displacements, large deformations, and contact between the bushing and the stabilizer bar was used for the numerical analysis. © 2018 Trans Tech Publications, Switzerland

FEM modelling techniques for three point bend test of rubber composites

This paper studies different modelling methodologies for a calculation of the three point bend test. Test samples are composed of a rubber matrix and either steel or textile cords reinforcement. Prior to the bending tests, all of the used materials including the matrix and the reinforcement were measured to find out their mechanical properties. Rubber materials were described using hyperelastic models. FEM software MSC Marc/Mentat is employed as a calculation tool and its various functionalities are utilized for a description of the test composite models. The main observed outcome is a dependence of the vertical force causing the test sample deformation on the amount of the deformation. Calculated results are compared to each other and to measurements. Then, all the modelling techniques are evaluated. © 2018 Trans Tech Publications, Switzerland