Optimization of a curvilinear thread profile in a planetary roller screw

The paper presents an application of the Finite Element Method (FEM) in stress analysis and optimization of thread profiles in cooperation of the roller with the screw in the planetary roller screw mechanism. The problem of the roller and the screw threads cooperation as well as related geometrical parameters were described. The optimization problem was formulated with the aim of obtaining a better effort of threads and lower contact pressure depending on the geometry

Application of finite element method in the optimal design of the nut with a groove in the end-face

The paper presents an application of finite element method in the optimal design of the nut with a groove in the end-face. There were described issues of the load distribution and FEM modeling of threaded connections. The optimization problem was formulated with the aim of obtaining the uniform load distribution on the bolt’s thread depending on the geometry of nut

Problem samopoczucia emocjonalnego i zaburzeń snu wśród pacjentów oddziału neurochirurgii – badania wstępne

Introduction. Depression and chronic pain have been among the top three leading causes of global disability in the world over the past three decades. The combination of chronic pain and depression leads to worse outcomes and overall functioning than either condition alone. Studying the links between pain, sleep and depression has become an important area of research. Aim. Assessment of pain, emotional state and sleep disorers among patients of the neurosurgery department. Material and Methods. The study was conducted among 63 neurosurgery patients. Standardized research tools were used: Visual Analogue Scale, Beck Depression Scale, Pittsburgh Sleep Quality Index. Statistical analysis was performed using Spearman’s rho correlation test and Pearson’s χ2 test. Results. The respondents are mostly women (54%), aged 26–78; the average age was 54. In terms of the assessment of the emotional state, patients with no depressive symptoms (42.9%) and with a mild stage of depression (46%) were noted. 77.8% of the subjects declared reduced sleep quality. Most of the subjects reported moderate (44.4%) and mild (30.2%) pain. It was shown that greater intensity of pain was statistically significantly associated with greater severity of depression ρ=0.33; p<0.01 and higher severity of sleep disorders ρ=0.39; p<0.01. It was also found that people with higher levels of depression had greater sleep disturbances ρ=0.74; p<0.001. Conclusions. Problems with sleep and depression of varying severity characterize the majority of neurosurgical patients. Pain is one of the significant factors aggravating these disorders. (JNNN 2023;12(1):24–33)Wstęp. Depresja i przewlekły ból znalazły się w pierwszej trójce głównych przyczyn globalnej niepełnosprawności na świecie w ciągu ostatnich trzech dekad. Połączenie przewlekłego bólu i depresji prowadzi do gorszych wyników leczenia i ogólnego funkcjonowania niż każdy z tych stanów osobno. Badanie związków między bólem, snem i depresją stało się ważnym obszarem badań. Cel. Ocena bólu, stanu emocjonalnego i zaburzeń snu wśród pacjentów oddziału neurochirurgii. Materiał i metody. Badania przeprowadzono wśród 63 pacjentów neurochirurgii. Zastosowano standaryzowane narzędzia badawcze: Wizualna Skala Analogowa, Skala Depresji Becka, Kwestionariusz Jakości Snu Pittsburgh. Analizę statystyczną przeprowadzono testem korelacji rho Spearmana i testem χ2 Pearsona. Wyniki. Badani to w większości kobiety (54%), w wieku 26–78 lat; średnia wieku wyniosła 54 lata. W zakresie oceny stanu emocjonalnego zauważono pacjentów z brakiem objawów depresyjnych (42,9%) oraz z łagodnym stadium depresji (46%). 77,8% badanych deklarowało obniżoną jakość snu. Najwięcej badanych zgłaszało umiarkowane (44,4%) i łagodne (30,2%) dolegliwości bólowe. Wykazano, że większe nasilenie bólu powiązane było istotnie statystycznie z wyższym nasileniem depresji ρ=0,33; p<0,01 i wyższym nasileniem zaburzeń snu ρ=0,39; p<0,01. Stwierdzono również, że osoby z wyższym poziomem depresji miały większe zaburzenia snu ρ=0,74; p<0,001. Wnioski. Problemy ze snem i depresją o różnym stopniu nasilenia charakteryzują większość pacjentów neurochirurgicznych. Ból jest jednym z istotnych czynników pogłębiających te zaburzenia. (PNN 2023;12(1):24–33

Numerical computation of stresses and deformations in the planetary roller screw components

The paper presents finite element analysis of stresses and deformations of planetary roller screw components. The finite element model takes into account the frictional contact between helical surfaces. The results of numerical calculations for the contact problem were compared with the theoretical solution based on the Hertz theory. The obtained results can be used in the development of design procedures of planetary roller screw

Thermal and mechanical analysis of the internal support for LNG cryogenic road tanker

Road tankers for liquefied natural gas are designed as double-walled vacuum insulated tanks. The temperature difference between the fluid in the inner vessel and the environmental temperature can reachup to 200 K. Supports holding the internal vessel must be able to transfer complex mechanical loads occurring under operating conditions and at the same time minimize the heat leakage to the tank. In this paper the construction of a steel support with a composite insert for a 25 m3 tank was considered. The proposed design was tested in thermal and mechanical finite element analysis using ANSYS software

CFD analysis of air flow through the LNG ambient air vaporizer with longitudinal finned tubes

Ambient air vaporizers, depending on their efficiency, can be up to several meters high. Therefore, they can have a large outside surface area exposed to the wind. Forced air flow through the vaporizer structure have a beneficial effect on improving heat transfer from the environment. On the other hand, if the vaporizer is placed in the region of significant wind velocities, the wind forces acting on the structure can be considerable. This paper presents CFD analysis of air flow through the structure of the ambient air vaporizer with a 6 x 6 finned tube array. The effect of changing wind direction on the wind pressure and wind velocity distributions is investigated

Determination of Aerodynamic Drag Coefficients of Longitudinal Finned Tubes of LNG Ambient Air Vaporizers Using CFD and Experimental Methods

This paper presents the results of numerical and experimental studies of wind action on longitudinal finned tubes of LNG ambient air vaporizers. The main objective of the study was to determine the aerodynamic drag coefficients for longitudinal finned tubes with different number of fins considering various directions of wind action. Numerical calculations were performed using CFD analysis, while experimental tests were carried out in a wind tunnel test stand. The obtained results indicate the variation of tube loads depending on the number of fins and the direction of wind action and can be used in the design of ambient air vaporizers

Optimization of ER8 and 42CrMo4 Steel Rail Wheel for Road–Rail Vehicles

Railway track maintenance services aim to shorten the time of removing failures on the railways. One of the most important element that shorten the repair time is the quick access to the failure site with an appropriate equipment. The use of road-rail vehicles is becoming increasingly important in this field. In this type of constructions, it is possible to use proven road vehicles such as self-propelled machines or trucks running on wheels with tires. Equipping these vehicles with a parallel rail drive system allows for quick access to the failure site using both roads and railways. Steel rail wheels of road-rail vehicles are designed for specific applications. Since the total weight of vehicle is a crucial parameter for roadworthiness, the effort is made to minimize the mass of rail wheels. The wheel under consideration is mounted directly on the hydraulic motor. This method of assembly is structurally convenient, as no shafts or intermediate couplings are required. On the other hand, it results in strict requirements for the wheel geometry and can cause significant stress concentration. Therefore, the problem of wheel geometry optimization is discussed. Consideration is given to the use of ER8 steel for railway application and 42CrMo4 high-strength steel. Finite element analysis within Ansys software and various optimization tools and methods, such as random tool, subproblem approximation method and first-order method are applied. The obtained results allow to minimize the rail wheel mass with respect to the used material. Moreover, computational demands and methods leading to the best results are compared

Determination of Aerodynamic Drag Coefficients of Longitudinal Finned Tubes of LNG Ambient Air Vaporizers Using CFD and Experimental Methods

This paper presents the results of numerical and experimental studies of wind action on longitudinal finned tubes of LNG ambient air vaporizers. The main objective of the study was to determine the aerodynamic drag coefficients for longitudinal finned tubes with different number of fins considering various directions of wind action. Numerical calculations were performed using CFD analysis, while experimental tests were carried out in a wind tunnel test stand. The obtained results indicate the variation of tube loads depending on the number of fins and the direction of wind action and can be used in the design of ambient air vaporizers

Finite element analysis of heat flow through longitudinal finned tubes in the LNG ambient air vaporizer for a total frost case

Liquefied natural gas (LNG) is transported and stored in liquid state at temperature of -163C. In order to use natural gas directly in its gaseous form, LNG must be vaporized, which requires the input of heat. Ambient air vaporizers (AAVs) are commonly used for that purpose in LNG regasification stations. These heat exchangers consist of longitudinally finned tubes with a large heat transfer surface area, provide high efficiency and are virtually cost-free since the heat is taken from the ambient air. This paper presents the results finite element thermal analysis of heat transfer through the finned tubes of ambient air vaporizers under the conditions of total frosting