Materials Science Forum Vol. 952

Abstract: At present multiplicative plasticity theories are used to model material degradation of hyperelastic materials within the framework of finite-strain elastoplasticity. The theories assume that the intermediate configuration of the body is unstressed and that such multiaxially stretched bodies do not have compatible unstressed configurations. As a result, there does not exist a motion whose material gradient could define the plastic deformation gradient. The assumption is however not consistent with the theory of nonlinear continuum mechanics and the related theories are not continuum based. In this paper material degradation of a silicone cross-shaped specimen in biaxial tension is studied using a thermodynamically consistent Mooney-Rivlin material model. The material model is based on the first nonlinear continuum theory of finite deformations of elastoplastic media which allows for the development of objective and thermodynamically consistent material models within the framework of finite-strain elastoplasticity. Such material models are independent of the model description and the particularities of the model formulation and moreover they can relate the internal power density of the model to the internal power density of the specimen coming from the tensile test of the modelled material. In this paper a few analysis results are presented and briefly discussed.

Abstract: The purpose of this article is to add knowledge about the influence of preparation conditions on the resulting properties of polymeric (Nano) composites by a statistical view of the results.Most of the work on the preparation of (Nano) composites only deals with the description of the improvement or deterioration of properties without a more in-depth assessment of the statistical significance of the obtained results. In the article on the above name, the primary objective of the statistical proof of change in the strength of the tested materials will be the nanoplane content. The Yakima’s (polynomial interpolation method) will be used for the basic part of the evidence, which, by smooth interpolation, will enhance the functional dependence of the tensile strength of the modified and unmodified mixture on temperature and time.As a further one and for key evidence presented, application of cluster analysis methodology, namely the finding of a suitable calculation method based on the basic correlation matrix, will be used. The resulting evidence will then be confirmed using a further methodology, specifically cluster analysis.This article has proved to be able to prove that the obtained improvements in the properties of the prepared systems are also statistically significant.

Abstract: In order to find hyperelastic material model constants, data fitting technique is often used. For this task, the data is collected through different laboratory tests, namely, the uniaxial, the biaxial and the pure shear. However, due to the difficulty in getting biaxial data, often only uniaxial data was used for the fitting. Despite frequent use, it was established that this practice creates erroneous results. With a view to improve the data fitting results and at the same time to overcome the difficulty of collecting primary biaxial data, uniaxial data was used to generate a secondary biaxial data set. The data derived through this method was then tested with four common models as to examine the compatibility of the method. Subsequently, real biaxial data was used to compare with the data fitting results obtained through the proposed method. As results indicated combined data fitting for both instances were very much identical with respect to all tested models. Cases where somewhat higher deviation observed between experimental curves and data fitted curves for biaxial data, gave similar results for adjusted data driven data fitting too. However, such deviation could be attributed to mismatch between models with the particular material behaviour rather than the generated data.

Abstract: Electrical impedance tomography (EIT) is a perspective vital imaging method in medicine. Although the paper deals mainly with medicine application, the potential of EIT is also in the field of a novel material testing. EIT belongs to non-invasive methods. It is used mainly for the area of thorax since thorax exhibits the biggest changes in impedance. The lungs are mostly filled with air while surrounding flesh has impedance similar to water. However EIT has several drawbacks: relatively big measurement inaccuracy, blurred obtained images, difficulties in application of electrodes and problems with repeatability of measurements. Many drawbacks can be limited when an absolute tomography is used, though absolute tomography is very challenging and is rather only a laboratory concept then a real working method. This article deals with a robust method which is closely related to absolute tomography imaging while viable in clinical practice and to non-invasive material description in general. A unique measuring device VERA was developed. Such a device helps with fast application of electrodes and enables to get reproducible and reliable images of thorax or other volumes in engineering. The paper also discusses challenges when choosing a mediator material or liquid for EIT function. The concept of stiff framework for electrodes which is applied to patient is unusual but exhibits many advantages resulting in better images.

Abstract: Measurement of industrial parts is very important for current production. There are many different methods (contact and non – contact) for part ́s control. Every of those methods have some advantages and disadvantages. The biggest problem was found in measurement of very small parts or complex parts which have some inaccessible places. The solution was implementation of X-ray technology into the measuring process. It is called computed tomography or metrotomography (connecting metrology and tomography). This technology finds application in many different fields, especially in the automotive industry. The result of the method is cloud of points or generated STL models which are suitable for use in other software for evaluation. However, there is still question of the method accuracy and accuracy of the generated STL models. This paper is dealing with scanning of plastic part with X-ray technology, generating of STL models by different methods and their accuracy evaluation.

Abstract: Every organisation is a very complex system. It consists of soft and hard parts of a system. Their relationships and the influence of the substantial neighbourhood lead to the development of a number of problems. This article deals with nonconformities in the relationship to material aspects in management systems of organisations. Nonconformities were found from the survey which was conducted in organisations in a one region of the Czech Republic. There are from production, maintenance, store, quality department and so on. The article classifies nonconformities by a type, by a severity and by an amount. It describes the relation to risks of the management system and also to main and minor processes and to innovations. In conclusion, the article presents some recommendations for the increase of quality of a production and also for the simplification of the management system.

Abstract: Industrial robots are increasingly used to automate technological processes, such as machining, welding, paint coating, assembly, etc. Automation rationalizes material flows, integrates production facilities and reduces the need for manufacturing inventory, provides cost savings for human maintenance. Technology development and growing competition have an influence on production growth and increase of product quality, and thus the new possibilities in innovation of industrial robot are searched for. One of the possibilities is applying of an inertial navigation system into robot control. This article focuses on new trends in manufacturing technology: design of Inertial Measurement Unit (IMU) for a robotic application control. The Arduino platform is used for the IMU as a hardware solution. The advantage of this platform is low cost and wide range of sensors and devices that are compatible with this platform. For scanning, the MEMS sensor MPU6050 is used, which includes a 3-axis gyroscope and an accelerometer in one chip. New trends in manufacturing facilities, especially robotics innovation and automation, will enable the productivity to grow in production processes.

Abstract: Some modern methods of surface contamination detection use the principle of luminescence for their function. This thesis aims at introducing the principle of the method that is available for the measurement of surface contamination, thesis deals with an innovative surface-detection device using UV-VIS luminescence spectroscopy. In the work is presented the industrial use of the detection of oil contaminants. Another specialized topic is the field of forensic practice - dactyloscopy, where the possible use of the principle of UV-VIS luminescence spectroscopy, the Recognoil device as a possible and effective method of ensuring dactyloscopic traces is proved.

Abstract: Maintenance is a system-specific activity that the purpose of which is to maintain or to increase time, performance and quality of machines and equipment use. The demand for technological equipment is still rising, resulting in often complicated and lengthy repairs. It is necessary to analyze the tools used in the construction of assembly joints and to describe the deficiencies that may occur during assembly. When contacting a material tool using a particular technology and assembly, it is necessary to analyze the impact on the final surface quality of the material.

Abstract: Only some from series of non-destructive testing methods of material defects are employed for measurement of structural parameters of materials. The principle of acoustic and magnetic structuroscopy of cast irons and steel is explained. The examples of exploitation and equipment are described. At least two methods must be used simultaneously for strength and heat resistance measurement of composites, powder metallurgy products and cast irons. Development of this combined structuroscopy of cast irons. The equipment TELIT 3 was developed for evaluation of cast iron quality at critical sites of complicated castings (cylinder blocks of transport engines). The direction of furher research was indicated – exploitation of magnetic excited acoustic wave and combined structuroscopy of thin composite layers.