An Approach to Variation Simulation of Final Aircraft Assembly with Presence of Sealant

2021 ◽  
pp. 1-22
Author(s):  
Artem Eliseev ◽  
Sergey Lupuleac ◽  
Boris Grigor'ev ◽  
Julia Shinder
Keyword(s):  
Numerical Test ◽  
Assembly Quality ◽  
Final Assembly ◽  
Static Condensation ◽  
Determining Factors ◽  
The Difference ◽  
Structural Parts ◽  
Structure Assembly ◽  
Variation Simulation ◽  
Aircraft Panels

Abstract The article discusses the process of aeronautical structure assembly in the presence of a sealant between the parts to be joined. An attempt to estimate the influence of sealant on assembly quality in terms of variation analysis is presented. The sealant is considered as a highly viscous liquid that is applied to the surfaces of the assembled parts before the start of final assembly. The modeling approach is based on simulation of two-way coupled fluid-structure interaction between fluid sealant and compliant structural parts. Reynolds lubrication approximation is used in the fluid dynamics problem and variational formulation of contact problem combined with static condensation is used in the structural one. The joining of two aircraft panels is used as a numerical test for demonstration of developed approach. Various phenomena connected with the presence of sealant are demonstrated. In particular, the difference in the fastener loosening due to sealant flow between different types of fasteners is investigated. Results of variation simulation show that presence of sealant should be considered among determining factors in the analysis of assembly quality.

Combining Variation Simulation With Welding Simulation for Prediction of Deformation and Variation of a Final Assembly

2012 ◽  
Vol 12 (2) ◽  
Author(s):  
Andreas Pahkamaa ◽  
Kristina Wärmefjord ◽  
Lennart Karlsson ◽  
Rikard Söderberg ◽  
John Goldak
Keyword(s):  
Final Outcome ◽  
Positioning Error ◽  
Welding Simulation ◽  
Rotation Matrices ◽  
Heating And Cooling ◽  
Final Assembly ◽  
Geometric Tolerances ◽  
The Difference ◽  
Variation Simulation ◽  
Different Sources

In most variation simulations, i.e., simulations of geometric variations in assemblies, the influence from heating and cooling processes, generated when two parts are welded together, is not taken into consideration. In most welding simulations, the influence from geometric tolerances on parts is not taken into consideration, i.e., the simulations are based on nominal parts. In this paper, these two aspects, both crucial for predicting the final outcome of an assembly, are combined. Monte Carlo simulation is used to generate a number of different non-nominal parts in a software for variation simulation. The translation and rotation matrices, representing the deviations from the nominal geometry due to positioning error, are exported to a software for welding simulation, where the effects from welding are applied. The final results are then analyzed with respect to both deviation and variation. The method is applied on a simple case, a T-weld joint, with available measurements of residual stresses and deformations. The effect of the different sources of deviation on the final outcome is analyzed and the difference between welding simulations applied to nominal parts and to disturbed (non-nominal) parts is investigated. The study shows that, in order to achieve realistic results, variation simulations should be combined with welding simulations. It does also show that welding simulations should be applied to a set of non-nominal parts since the difference between deviation of a nominal part and deviation of a non-nominal part due to influence of welding can be quite large.

scholarly journals Variation Simulation of Fixtured Assembly Processes for Compliant Structures Using Piecewise-Linear Analysis

2005 ◽  
Author(s):  
Michael L. Stewart ◽  
Kenneth W. Chase
Keyword(s):  
Piecewise Linear ◽  
Element Model ◽  
Linear Analysis ◽  
Elastic Analysis ◽  
Variation Analysis ◽  
Linear Elastic ◽  
Final Assembly ◽  
Compliant Part ◽  
Assembly Operations ◽  
Variation Simulation

While variation analysis methods for compliant assemblies are becoming established, there is still much to be done to model the effects of multi-step, fixtured assembly processes statistically. A new method is introduced for statistically analyzing compliant part assembly processes using fixtures. This method yields both a mean and a variant solution, which can characterize an entire population of assemblies. The method, called Piecewise-Linear Elastic Analysis, or PLEA, is developed for predicting the residual stress, deformation and springback variation resulting from fixtured assembly processes. A comprehensive, step-by-step analysis map is presented for introducing dimensional and surface variations into a finite element model, simulating assembly operations, and calculating the error in the final assembly. PLEA is validated on a simple, laboratory assembly and a more complex, production assembly. Significant modeling issues are resolved as well as the comparison of the analytical to physical results.

scholarly journals Presentation of winter flower-dub lesions of peach varieties originating from different growing areas

2007 ◽  
pp. 70-73
Author(s):  
Mária Dani
Keyword(s):  
Critical Points ◽  
Frost Damage ◽  
Frost Tolerance ◽  
Great Plain ◽  
Flower Buds ◽  
Determining Factors ◽  
Tolerant Variety ◽  
The Difference

Although there are many critical points in peach production, in Hungary, winter frost damage is one of the most significant. Serious winter frost damage on the Hungarian Great Plain was the focus of our experiments. The adequate growth and the most adaptable varieties are determining factors in peach production. In our experiments, we compared three growing areas (Siófok, Sóskút, Szatymaz) and four different varieties (Suncrest, Redhaven, Meystar, Michellini). Throughout these growing areas and with varieties, we wanted to demonstrate the differences in the frost damage values of the flower buds in 2005 and 2006.In the course of the statistical trials, we found that the difference between the varieties is significant (table 2). The most tolerant variety as for frost tolerance is the ‘Michellini’ variety, and the worst is the ‘Suncrest’ variety. We also found that these data are significant. When we examined the varieties according to their growth, we got the same results (table 3). We determined that the differences between growth are significant and related to these four varieties and the two years (2005-2006), that frost damage was the highest at Szatymaz, and that it was the lowest in Sóskút.

scholarly journals On the transition pattern of the oblique detonation structure

2012 ◽  
Vol 713 ◽  
pp. 659-669 ◽  
Author(s):  
Hong Hui Teng ◽  
Zong Lin Jiang
Keyword(s):  
Chemical Activation ◽  
Smooth Transition ◽  
Instability Criterion ◽  
Detonation Waves ◽  
Abrupt Transition ◽  
Detonation Structure ◽  
Determining Factors ◽  
Angle Difference ◽  
The Difference ◽  
Detonation Instability

AbstractOblique detonation waves are simulated to study the evolution of their morphology as gasdynamic and chemical parameters are varied. Although two kinds of transition pattern have previously been observed, specifically an abrupt transition and a smooth one, the determining factors for the transition pattern are still unclear. Numerical results show that the transition pattern is influenced by the inflow Mach number, chemical activation energy and heat release. Despite the fact that these parameters were known to influence the detonation instability, the transition pattern variation cannot be predicted according to the instability criterion. In this study, the difference in the oblique shock and detonation angles is proposed as the criterion to determine the transition pattern with the aid of shock-polar analysis. It is found that the smooth transition will appear when the angle difference is small, while the abrupt transition will occur when the difference is large. The shift from the smooth transition to the abrupt transition occurs when the angle difference is about $1{5}^{\ensuremath{\circ} } $–$1{8}^{\ensuremath{\circ} } $. The previously proposed criterion using the characteristic time ratio is also examined and compared with the present angle difference criterion, and the latter is proved to provide better results.

scholarly journals Association between Consumed Foods and Musculoskeletal Disorder in Office Workers

2021 ◽  
Author(s):  
Golnaz Arjmand ◽  
Pardis Irandoost ◽  
Mojtaba Abbaszadeh ◽  
Aliasghar Farshad ◽  
Masoud Salehi ◽  
...  
Keyword(s):  
Musculoskeletal Disorder ◽  
Food Group ◽  
Cross Sectional Study ◽  
The Body ◽  
Office Workers ◽  
Food Groups ◽  
Anthropometric Parameters ◽  
Cross Sectional ◽  
Determining Factors ◽  
The Difference

Background: Musculoskeletal disorder (MSD) is one of the important problems concerning the staffs' health and productivity in the workplace. Nutritional status and consumption of some foods are also among the determining factors of MSD. So, this study aimed to evaluate the correlation of diet and consumed food groups with MSD. Methods: This cross-sectional study was conducted on 100 office workers. The participants' anthropometric parameters and their dietary information were collected using a semi-quantitative food frequency questionnaire. The findings were categorized into nine levels. The total scores were calculated for all the items per food group and per person. Nordic musculoskeletal questionnaire was also administered to evaluate the MSD symptoms in nine parts of body. Results: The score of consumed food groups was compared between individuals “with pain” and “without pain” in nine parts of the body. The scores of fruit intake in individuals “with pain” and “without pain” were 2.94 ± 1.27 vs. 3.29 ± 1.16 and 2.81 ± 1.10 vs. 3.49 ± 1.38 in terms of neck and wrists, respectively. The difference between the two groups were significant (P < 0.05). Furthermore, the participants with pain in the neck consumed significantly lower amounts of cereals and nuts (P = 0.03, 0.04). In the case of the shoulder pain, consuming legumes and nuts in the “without pain” group was higher than the group of participants who had pain (P = 0.01, P = 0.03). Fat intake was higher in the patients who had pain in their hips (P = 0.02). Conclusion: Less pain was reported in the musculoskeletal system by higher consumption of fruits, nuts, and legumes. It seems that plant-based dietary pattern is more effective in musculoskeletal health.

scholarly journals Perilaku gizi dan hidrasi selama kehamilan berhubungan dengan konstipasi

2020 ◽  
Vol 9 (1) ◽  
pp. 27-32
Author(s):  
Khairizka Citra Palupi ◽  
Mertien Sa’pang ◽  
Erry Yudhya Mulyani ◽  
Aditya Fatkhi Laili
Keyword(s):  
Pregnant Women ◽  
Health Centre ◽  
P Value ◽  
Differential Analysis ◽  
Public Health Centre ◽  
Attitudes And Practices ◽  
Hydration Behaviour ◽  
Arm Circumference ◽  
Determining Factors ◽  
The Difference

Background: Prevalence of constipation in pregnant women is estimated at 11-38%. Impact of constipation in pregnant women are haemorrhoids and decreased quality of life. Meanwhile, determinants known to influence constipation during pregnancy are hormonal changes, poor diet, low physical activity and lack of fluid consumption. Objectives: Identify the determining factors that can affect occurrence of constipation and investigated the difference based on constipation status among pregnant women in Public Health Centre in Jakarta, Indonesia;Methods: This research was a cross sectional design conducted in July 2019 to October 2019. The subject was pregnant women. We used accidental sampling method to recruit subjects in Public Health Centre, Kebun Jeruk, West Jakarta. We measured the determining factors of constipation among pregnant women. Characteristic of pregnant women, knowledge, attitudes and practices were measured by questionnaires. Anthropometrics data for weight, height, and mid arm circumference were measured. Haemoglobin level was also measured. Bivariate analysis using Pearson or Spearman was used to investigate which factors associated significantly with constipation among pregnant women. We also assessed the difference of characteristic of pregnant women, knowledge, attitudes and practices using differential analysis (Mann-Whitney U-test). Results: The results showed that prevalence of constipation was 30%. Differential analysis showed that mothers who experienced constipation had a younger age and low nutritional and hydration behaviour scores. Other variables such as gestational age, weight before pregnancy, upper arm circumference, height, haemoglobin, knowledge score and nutritional attitude and hydration did not show significant differences based on constipation status. Correlation analysis showed an inverse relationship between maternal age and incidence of constipation, with r = 0.242 and a p-value = 0.015. Maternal age, nutritional behaviour and hydration also showed significant inverse relationship with incidence of constipation (r = -0.206 and p-value 0.039);Conclusion: Nutritional and hydration behaviour during pregnancy was related to the occurrence of constipation. Mothers are advised to have good nutrition and hydration behaviour to prevent constipation.

scholarly journals Comments on “The nature of theory in information systems”

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Sajjad Hussain ◽  
Imran Bashir Dar
Keyword(s):  
Information Systems ◽  
Action Theory ◽  
Clear Understanding ◽  
Structural Breakdown ◽  
The Difference ◽  
Structural Parts

AbstractThis commentary is on Shirley Gregor’s (2006) article titled “The Nature of Theory in Information Systems”, published in MIS Quarterly. In terms of theories, five types have been prominent in Gregor’s classification: (a) Theory of Analyzing (b) Theory of Explaining (c) Theory of Prediction (d) Theory of Explaining and Predicting (e) Theory of Design and Action. The author argued that this can help researchers to choose a differing epistemological approach to develop a theory that is under development. Furthermore, a structural breakdown of the theory has been projected that gives a better and clear understanding of the essential parts of the theory to researchers. However, some important questions emerge after reading the most cited article about the nature of theory in IS. The major ones are: (a) What is the difference between theory in general and theory in IS?, (b) Are the structural parts of the theory described by Gregor exhaustive and correctly presented?, (c) Different classifications of theories presented by Gregor are theory or theorizing in nature, and finally, (d) Gregor argued that management scientists did not provide anything regarding design and action theory, is that true?

A Simplified Lattice Boltzmann Method without Evolution of Distribution Function

2016 ◽  
Vol 9 (1) ◽  
pp. 1-22 ◽  
Author(s):  
Z. Chen ◽  
C. Shu ◽  
Y. Wang ◽  
L. M. Yang ◽  
D. Tan
Keyword(s):  
Distribution Function ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Equilibrium Distribution ◽  
Numerical Test ◽  
Distribution Functions ◽  
Navier Stokes ◽  
Equilibrium Distribution Function ◽  
The Difference ◽  
Boltzmann Method

AbstractIn this paper, a simplified lattice Boltzmann method (SLBM) without evolution of the distribution function is developed for simulating incompressible viscous flows. This method is developed from the application of fractional step technique to the macroscopic Navier-Stokes (N-S) equations recovered from lattice Boltzmann equation by using Chapman-Enskog expansion analysis. In SLBM, the equilibrium distribution function is calculated from the macroscopic variables, while the non-equilibrium distribution function is simply evaluated from the difference of two equilibrium distribution functions. Therefore, SLBM tracks the evolution of the macroscopic variables rather than the distribution function. As a result, lower virtual memories are required and physical boundary conditions could be directly implemented. Through numerical test at high Reynolds number, the method shows very nice performance in numerical stability. An accuracy test for the 2D Taylor-Green flow shows that SLBM has the second-order of accuracy in space. More benchmark tests, including the Couette flow, the Poiseuille flow as well as the 2D lid-driven cavity flow, are conducted to further validate the present method; and the simulation results are in good agreement with available data in literatures.

Sensitivity of the actinidia (Actinidia arguta Siebold & Zucc.) plants above ground part to the low temperatures effect

2020 ◽  
pp. 197-204
Author(s):  
O.I. Rudnyk-Ivashchenko ◽  
◽  
V.A. Kryvoshapka ◽  
M.M. Tsandur ◽  
V.I. Grusha ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Damage Index ◽  
The Black Sea ◽  
Damage Level ◽  
Actinidia Arguta ◽  
Black Sea Coast ◽  
The Difference ◽  
Structural Parts ◽  
Total Damage ◽  
Ground Part

The аuthоrs have elucidated relevance of the studies of the actinidia (Actinidia arguta) plants in the conditions of the Black Sea coast Northern Steppe, and analyzed the influence of the low temperatures on the structural parts of shoots: bark, cambium, wood, core of the two forms of the French breeding – female (two cultivars) and male (one). According to the analyzes results, the aboveground parts of culture of the both forms plant are sensitive to the low temperatures effect, but it was the core tissues of the shoot that were the most vulnerable in the experiment. Thus, in the plants of the female form of variety O aften the I exposure to frost -20 0C, the damage index was at a level of 1.2, while that of the variety in the same variant was by one point higher than of the previous one. Concerning the forms the male plants the most resistant to the low temperatures. The level of those forms was be 2.4 points higher than of the culture of female form. The total indicator of the damage of the shoots which in the variant which the lowest temperature -30 0C the parts of its plants (wood and core of the top, as well as the wood of the middle and through the bud) had the least damaged. Their resistance was by 2.4 points higher as compared to female cvs (total damage to the shoots in variant 4 was 31.4). The varietal actinidia plants characteristics were noted in response to the low temperatures influence in the context of one form. The highest damage level the female form as concerns the variely O in variant 4 (-30 0C) on the sections through the bud, which achieved 3.8 points, while as for cultivar F in same variant 2.9 points. The reaction of the bark tissues in the plants of the female form F under the effect of cold at -20 0C exceeded the level of damage for the plants of same form O more than by twice - 0.7 and 0.3 points respectively. Cooling of the plants aboveground parts to -25 0C revealed close indicators of the damage level to the bark tissues in the same representatives of actinidia O and F: 0.9 and 1.0 points respectively. In the connected which the maximum cooling level (-30 0C), the difference in the cold resistance was much larger. The damage level to the bark tissues in the female forms plants F was 3.5 points, and the level of representatives of O 2.5 points, that is 28.6 % lower. The results of the research proved the positive endurance of the actinidia plants under the conditions of growing in the investigations zone.

Variation Simulation of Dissimilar Materials Using Clip Fasteners

2016 ◽  
Author(s):  
Kristina Wärmefjord ◽  
Rikard Söderberg ◽  
Lars Lindkvist
Keyword(s):  
Material Properties ◽  
Dissimilar Materials ◽  
Temperature Changes ◽  
Sheet Metal Parts ◽  
Final Assembly ◽  
Geometrical Variation ◽  
Effects Of Temperature ◽  
The One ◽  
Variation Simulation ◽  
Selection Of

The use, and the joining process, of dissimilar materials have recently been highlighted. Joining of dissimilar materials can however be problematic, due to different material properties. Different materials respond differently to temperature changes and this might lead to deformations and stress in the final assembly. The joining methods differ also often from the one used to join similar material. Variation simulation is used to predict the geometrical variation of a subassembly or a final product. In variation simulation of dissimilar materials it is important to include material properties in order to achieve an accurate result. Also the effects form joining method must be included in the simulation. To join dissimilar materials like plastic and sheet metal parts, clip fasteners are often used. This paper presents a method for variation simulation of dissimilar materials with a focus on how to model clip fasteners. The method allows effects of temperature changes on holding forces and geometrical variation in the final assembly to be evaluated. Holding force refers to the force a clip fastener must withstand after the parts are joined. The method proposed can be used to support the design and selection of clip fasteners.

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