Influence of Pressure and Temperature on the Strength Properties of a Laminate Produced by the RTM Method

This paper discusses the effect of pressure on the content of microvoids and defects inside laminates fabricated under different pressures, by vacuum methods. Two basic vacuum methods resin transfer molding (RTM) and vacuum bag method were used in this paper. A glass mat with an alignment angle of (0□/90□) and a mass of 450 g/cm2 was used to produce the laminate, and a polymer resin was used as the matrix. Special attention was paid to the technological parameters of both processes. A mathematical analysis of the most important parameters which include flow rate, permeability, and gelation temperature has been carried out. In addition, the resin temperature is used to reduce the viscosity of the resin to facilitate its flow through the reinforcement, and in the final stage of production to control the chemical reactions occurring in the mold. The pressure is chosen so that the resin flow is continuous. The synchronization of these two parameters and the measurement of the time in which they occur are called the “cure cycle”. In the final step of the study, the composite was subjected to a static tensile test, using specimens of two different dimensions (scale effect) to evaluate the effect of microvoids and microcracks created by the processes on the strength of the material.

Laboratory Stand for Simplified Verification of Missile Dynamics for Didactic Purposes

The purpose of this study was to describe dynamics of missile based on bibliography, simplify the model to the easiest form, and verify it with the use of a designed laboratory stand. Next, a simple control system of the missile was designed. The stand is prepared for didactic purposes. A mathematical model was derived by applying Newton's second law together with the earth's coordinate system and the base coordinate system. Parameters of the actual rocket model were determined using the created laboratory stand. Synthesis of the rocket roll system was designed using Simulink PID Tuner application (MathWorks, Inc. Natick, Massachusetts, USA). A control system was based on a proportional-integral (PI) regulator. The designed control system was subjected to simulated tests in MATLAB Simulink (MathWorks, Inc. Natick, Massachusetts, USA).

Modeling Epitaxial Layer Growth from Gas Phase for Analysis of Influence of Changing Technological Process with Variation in Growth Zone Heating

In this paper, we analyze the nonstationary heat transfer during growth of epitaxial layers in epitaxy reactors from the gas phase. Based on this analysis, we formulate several recommendations on organization of heating of the growth zone for increasing homogeneity of epitaxial layers. We introduce an analytical approach for analysis of heat transfer during the growth of epitaxial layers from the gas phase. The approach gives a possibility to simultaneously take into account the nonlinearity of heat transfer, as well as changes of their parameters both in space and time.

On Optimization of Manufacturing of a Comparator in Track State to Increase Integration Rate of Elements

In this paper, an approach to increase integration rate of elements of a comparator in track state was introduced. Framework the approach a het-erostructure with special configuration was consider. Several specific are-as of the heterostructure should be doped by diffusion or ion implantation. Annealing of dopant and/or radiation defects should be optimized.

Determination of contact pattern for double enveloping worm gear

The paper presents the method of determining geometric contact pattern by using the direct computer-aided design (CAD) method for ideal globoid worm gear in which mounting deviations are considered. The tooth contact analysis was performed for all cycle of worm rotation. Based on the results of temporary contact pattern, graphical characteristics of the contact area size depending on worm position were made. A complete analysis of the correctness of gear meshing can be obtained based on presented method. If the worm or worm wheel is incorrectly designed in terms of the geometry, the meshing simulation of CAD models can indicate the collision. Geometric contact pattern analyses were made at two pressure angles of ideal gear. The analysis of the influence of mounting deviations was done against one selected pressure angle and one gear position.

Effect of grain size on the physicomechanical properties

In this study, locally available waste coconut (Cocos nucifera) shells (CSs) were investigated as possible replacement for asbestos-based brake pads. The CS-based brake pad was tested for its physicomechanical properties and compared with a commercial brake pad used as control sample. The results showed that (a) an improved interfacial bonding between the CS particles and the binder as the grain size decreases; (b) the 90 μm grain size sample had better physicomechanical properties than the control sample in all tests except the thermal conductivity and stability tests; and (c) the hardness, compressive strength, and density of the CS-based brake pad decreased with increasing grain size, whereas the absorption properties increased with increasing grain size. The study showed that further reduction of the grain size below 90 μm and matrix impregnation with metals of good thermal conductivity could provide significant improvements to properties of the CS-based brake pad.

The replication method to analyze roughness of shaft, tool, and grinding wheel microgeometry

This article presents the possibility of using the replication method to measure selected parameters of the surface geometry. The results of the tests obtained while measuring the replica and surface of the tested object are presented. The obtained results indicate the suitability of using RepliSet F5 to measure the roughness parameters (Ra and Rz), microgeometry tool, and grinding wheel. It has been proven that the replication method using the RepliSet F5 is suitable for chosen parameters of roughness and tool microgeometry measurements. However, it is not suitable for measuring the porosity of a grinding wheel.

Modeling the Kinematics of Two Robots with Denavit–Hartenberg Notation

This article presents a description and methodology for building a kinematics model for the formation of two-wheeled mobile robots transporting a beam using Denavit–Hartenberg notation. The simple and inverse kinematics tasks of this formation were solved. Solutions of kinematics tasks are presented in junction coordinates and global coordinates. The obtained results were simulated using the Matlab–Simulink package together with animation of the solution using a programmed emulator of robot work.

Microstructure and hardness of Pyrowear 53 steel after low-pressure vacuum carburizing at 921°C

The present paper studies and analyzes the low-pressure vacuum carburizing of Pyrowear 53 steel. The carburizing was performed at 921°C. The results after the completion of the treatment process are presented, i.e. microstructure of the surface layer and hardness. The results confirm that carburizing can be effectively used in hardening of the steel.

Decarbonizing of Ductile Cast Iron Surface for Usage in Two-Layered Casting

The main purpose of the present study is to verify the possibility of decarbonizing the surface of heat-resistant ductile iron GJS-XSiMo5-1 to provide a significant difference in carbon content between this material and gray cast iron ENGJL-250. In the future, this will allow to increase the diffusion of elements during the creation of the two-layered material using the casting process with materials in a liquid state and solid state. The above method was assumed to solve the problem of defects on turbocharger’s housing in an economically justified manner which occurred in some high-performance premium applications. Evaluation of decarbonized surface quality was investigated by microstructure observation (light microscopy) and alloy elements diffusion (scanning electron microscopy), and hardness measurement and the element content were checked by spark optical emission spectrometry and glow discharge optical emission spectrometry, respectively.