Optimization and fast prototyping of polymer parts exposed to cyclic loading

Many mechatronic systems operate with parts made of polymers. This cost-effective solution is also easy to design. Manufacturing is trivial for producers who produce millions of parts. The solution is more complicated when the fatigue and loading is a significant factor. The paper describes the development of polymer parts that are loaded by cyclic operation. The number of cycles in a specific application can be around 1 million. The specific case also deals with a corrosion environment around these components. Gasses in the environment cause degradation of material and failure of parts made of specific polymers. This interaction limits the choice of suitable materials. The mechanism operates in two directions which define the opening of a valve and free turn. Two variants of elastic valves were analysed. Loading states were simulated by final element methods. Internal stresses and contact stresses were analysed. Results were compared with long-term test results. The material creep and other material properties define the function of elastic parts after thousands of cycles. The technology of mould fabrication was analysed considering simplification and general effectivity of production. Prototype valves were printed by FDM 3D printer and tested. Prototype moulds were printed by SLA 3D printer, which produces high-temperature stable polymer. This procedure shows cost-effective prototype development and test procedures.

Performance degradation of metal rubber seal under high temperature and pressure

Seals are crucial components of mechanical devices; seal degradation limits the performance of mechanical systems and even causes accidents. In this work, we used a complex sealing test system to conduct long-term leakage experiments of metal rubber seals as a function of temperature and pressure. The leakage rate was the performance degradation indicator. We developed an experimental performance degradation pattern by linear regression. We combined the leakage pattern of metal rubber seals with leakage theory and found that the increase in the equivalent leakage channel height is the immediate reason for metal rubber seal performance degradation, itself fundamentally attributable to the time-dependent plasticity caused by material creep.

COMPARATIVE EVALUATION OF THE CREEP OF PISTON ALUMINUM ALLOYS

The paper deals with the issues of reliability of piston materials in the process of increasing engine power. It is precisely the increase in the liter power of engines while ensuring environmental and economic requirements that is today one of the main areas of work in engine manufacturing. Studies have shown that material creep has significantly affects on the reliability of internal combustion engine parts. The most thermally loaded engine element is a piston. The main critical areas for it can be identified: the edge of the combustion chamber, the area of the piston rings and the piston skirt. The appearance of seizures on the piston skirt is sometimes observed even during the engine initial tests at the engine power increasing. Thus, we can speak about the relevance of the problem of identifying the reasons for reaching the critical state of the piston material. Based on these data, it becomes possible to develop measures to ensure the reliable operation of the piston. Among the most common materials for the manufacture of pistons are aluminum alloys AL25 and AK4. The chemical composition of these alloys varies considerably. The study obtained coefficients for calculating the creep rate for these materials. The identification of the calculation of the creep deformation of aluminum alloys at different stress levels, for different temperatures is carried out. The upper boundary of the region of model adequacy in terms of temperatures and stresses is determined. The creep rate of aluminum alloys is analyzed at different temperatures. In the conclusions, a comparison of the piston materials is made and the advantages of the AK4 alloy in comparison with the AL25 alloy, which are coming out when the engine power is increased, are indicated. The direction of further research is also indicated, which is associated with the analysis of the deformation of the considered materials at the first stage of creep.

Modyfikacja znormalizowanej metody prowadzenia prób ciśnieniowych celem jej wykorzystania do badania szczelności gazociągów z poliamidu PA 12

Before being put into operation, gas pipelines are subjected to leakage and strength pressure testing. In the case of plastic gas pipelines, a combined leakage and strength test is performed at a pressure of 1.5 ´ MOP. In Poland, in accordance with the applicable regulations, the plastic material from which gas pipelines can now be built is polyethylene. In other countries gas pipelines are also built of another material, which is PA12 polyamide. Piping systems made of this material are used to transmit gas at a pressure of 1.6 MPa. Both polyethylene and polyamide gas pipelines, after loading them with internal pressure, will undergo deformation with time, which is called the material creep phenomenon. As a result, in pressure leakage tests of gas pipelines made of thermoplastics, such as polyethylene and polyamide, it is necessary to take this phenomenon into account. Due to the different properties of polyethylene and polyamide, the amount of deformation per unit time will be different, and therefore the test procedures that are used for polyethylene gas pipelines cannot be directly used for testing polyamide gas pipelines. An example of such a procedure is the one described in point A.27 of PN-EN 805: 2002. It is mainly used for leakage testing of polyethylene water pipelines and its application for leakage testing of PA12 polyamide gas pipelines with a MOP of 1.6 MPa requires changes in the test conditions. The article presents the concept of modifying the parameters of the hydrostatic method, taking into account the different properties of PA12 pipes compared to polyethylene pipes. Particular attention was paid to the higher value of Young's modulus and the related ring stiffness of PA12 polyamide pipes compared to polyethylene pipes. In order to obtain the appropriate deformation of the pipe resulting from the material creep, the time of holding the sample under pressure was experimentally extended before starting the actual test. After establishing the required test conditions for the sealed system, tests with simulated leaks were carried out. The obtained results of tests on airtight samples and with simulated leakage confirmed the possibility of using the modified method to test the tightness of PA 12 polyamide gas pipelines with a MOP of 1.6 MPa.

Non-Rigid Rotating Motion Effect on Creep Behavior for Infinite Cylinders under Thermomechanical Loading

The effect of non-rigid motion on creep analysis for cylinders have been investigated. inner surface of the cylinder is exposed to a uniform heat flux and for cooling the outer surface of the cylinder an air steam is applied to it. The cylinder is subjected to a body force. That produced by rotating cylinder about its own axis. It is assumed the cylinder is not rigid. Therefore, using equations of equilibrium, stress–strain and kinematic equation, governed equation which includes redial displacement and creep strains, is obtained. The material creep constitutive model is defined by the Bailey-Norton time-dependent creep law. From a solution consisting of analytical solution and iteration method has been used to obtain history of stresses and deformations during creep evolution of rotating cylinders. Therefore, Prandtle-Ruess equation substituted in equilibrium equation in the rate form, the radial displacement rate is obtained for plane strain condition. To investigate the effect of non-rigidity, the non-rigidity parameter (ζ) is defined and its effect on the creep behavior of the structure is investigated. It was revealed that Considering the structure as rigid does neglect the amount of stresses and radial displacement. History of stresses and displacement during 20 years are studied and it is observed that the changes have not accrued in recent years. The effect of velocity is another parameter that is investigated its effect on structural behavior during the time. it was revealed that, velocity has significant effect on structural behavior which cause trend of variation behavior change from linear to polynomial curve.

Design and Introduction of Thermal Collection Network (TCN) for the Thermal Management in 3-D IC Structures

Power in Watts of the chip, per unit area is growing exponentially in the electronic industry. At the same time, thermal problems becoming side effects of huge power consumption. Continuous efforts are getting made to remove the thermal problems of electronic packaging and systems. Thermal problems if not alleviated or suppressed, will lead the dielectric breakdown, electromigration, material creep, thermal cycling, chemical reactions, board warpage, performance drift, indirect heating, and many more problems. Likewise, a dedicated Power Delivery/distribution Network (PDN), can deliver the power to the chip base, this paper has introduced a new methodology of a dedicated Thermal Collection Network (TCN) in the same Back End Of Line (BEOL) area of the System in Package (SiP), System on Chip (SOC) and any other power-consuming chips. Adding a Thermal Through Silicon Via (TTSV) is another advantage in it. Using such an apparatus or methodology connected to TTSV will quickly pump-up the thermal energy to the heat-sink-fan assembly. Hence, preempting of heat from its sources can manage the thermal problems inside the chips or 3-D IC structures. The methodology uses the same copper metal stripes inside the Inter-Layer/Level-Dielectric (ILD), which will not lead to any extra copper to introduce more Coefficient of Thermal Efficiency (CTE) mismatch problems. It would be considered as one among the other metal stripes. The experimental results using the Finite Element Method (FEM) tool shown that 32% heat suction occurs in the TCNs, in monolithic ICs, and 11% in 3-D IC structures, compared to without such an approach. The junction temperature remained at 35%, with and without such an approach, in 3-D IC structures. This might lead to a new methodology for designing electronic chips and 3-D IC structures, in the future.

THE RIGIDITY OF THE EXTERNAL WALL PANEL WITH OPENING OF RESIDENTIAL BUILDING I-515/5 SERIES IN CASE BIAS

There were a number of characteristic damages and defects in typical panel houses when examine, one of which are tilts and biases of wall panels. The stiffness of the wall panel with the opening of residential building I-515/5 series has been determined at a given bias in its plane. The panel was calculated numerically using a nonlinear deformation model by the finite element method and analytically. The software package, LIRA-SAPR 2017, was used in this investigation. The calculation was carried out taking into account the nonlinearity and material creep. As a result, the fields of normal and shear stresses in the panel were obtained and the shear rigidity was calculated. The analysis of the obtained results showed that a possible decrease of the actual stiffness of the panel should take into account against the calculated stiffness was obtained according to the standards.

ELECTRON RADIATION EFFECT ON INDENTATION CREEP OF CONSTRUCTION POLYMERS

Cross-linking is a process in which polymer chains are associated through chemical bonds. Radiation, which penetrated through specimens and reacted with the cross-linking agent, gradually formed cross-linking (3D net), first in the surface layer and then in the total volume, which resulted in considerable changes in specimen behaviour. Creep value is an important parameter that describes the behaviour of a material for the duration of its exposure to long term stress. Most of the technical parts used in industry are subjected to the long term stress for their whole life cycle. This can lead to material creep, which directly results in the transformation of dimensions. To eliminate this problem, a number of construction materials was chosen and subsequently irradiated by a source of electrons. This created a 3D network within the polymer structure, which led to an increase of the micro-mechanical and micro-creep properties. Evaluation of these modifications was done by state of the art device Micro-combi tester manufactured by Anton Paar. This device lowers the time required to measure the creep by standard technology and it fluently records the changes of indentation depth in relation to applied force. This dependence is then used to calculate the creep values. Due to the electron irradiation, a 40 % increase was reached in creep resistance; therefore the useful properties of selected construction materials were improved.