Computer Simulation of the Press Fit Connection

2021 ◽  
pp. 3-11
Author(s):  
M.A. Lyubchenko ◽  
Martinez Juan Marcos Garcia ◽  
Quintana Laura Angelica Samora ◽  
V.S. Syromyatnikov
Keyword(s):  
Computer Simulation ◽  
Statistical Analysis ◽  
Reference Data ◽  
Statistical Significance ◽  
Modern Technology ◽  
Time Saving ◽  
Press Fit ◽  
The Press ◽  
Assembly Technology ◽  
Computing Speed

The design of modern technology is associated with increased requirements for strength and manufacturability. Press fit connections of small size parts can withstand significant workloads, so they are widely used in mechanisms and machines. Traditionally, the calculation of press fit connections is performed according to classical formulas using a large amount of reference data. The calculations use standard recommendations that make it easier to obtain solutions with a minimum investment of time. However, the time saving limits the search to a few joints, which are not always the best in some indicators. Modeling press fit joints with different combinations of parameters leads to the formation of hundreds of potential joints. To check their performance, it is necessary to use modern computing facilities. The computer has almost unlimited possibilities for computing speed and storing arrays of information. Simulation of press fit connections on a computer allows obtaining regression metamodels, accessing the statistical significance of parameters, and determining the area of workable connections. It becomes possible to optimize the design of the joint in terms of strength, weight and assembly technology. The system for calculating and statistical analysis of press fit connections has been developed on the basis of existing standards. A program has been developed providing the joints formation and verification with an assessment of their suitability for the specified requirements.

scholarly journals Cementless vs Cemented Total Ankle Arthroplasty: A Prospective Comparison of the Laterally Placed Trabecular Metal Ankle

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0045
Author(s):  
Alastair S.E. Younger ◽  
Federico G. Usuelli ◽  
Donald Bohay ◽  
Fabian Krause ◽  
Eric Giza ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Pain Scale ◽  
Rank Test ◽  
Trabecular Metal ◽  
Chi Square ◽  
Press Fit ◽  
Early Results ◽  
Prospective Comparison ◽  
The Press ◽  
Difficulty Scale

Category: Ankle, Ankle Arthritis Introduction/Purpose: The laterally placed trabecular metal ankle replacement is placed using a jig and a fibular osteotomy. The tibia and talus are reamed to match the curved contour of the replacement. Additional fixation is achieved using two rails on the tibial and talar component. Additional cement fixation can be used by a bead of cement on the rail to assist in early component fixation. Cement fixation did not cover the entire ingrowth surface but was only used on the rails as per the technique manual. The purpose of this study is to compare the early results of 113 total ankle replacements with and without rail cement. Methods: 121 patients were enrolled in a prospective study. 10 centers were involved. 3 patients underwent revision and 5 withdrew (1 death, 2 lost to follow up and 2 requested discontinuation). Patients were assigned cement or no cement based on the surgeons practice. EQ5D, AOFAS, AOS scores were obtained preoperatively and at 6 weeks, 6 months, and yearly thereafter. Revision of metal components for infection or loosening were secondary end points. Statistical significance was tested by the Wilcoxon Signed Rank Test 26 and set at p= 0.05. 95% confidence intervals are given. 59 ankles had cement, and 53 had press fit. The demographics showed the cement augmentation patients were heavier and older. The cement cases had longer surgical times (169 minutes, CI 159 to 179 vs 154, CI 144 to 163). Of 113 cases, 113 were followed at 1 year, and 100 at 2 years and 67 at 3 years. Results: The press fit components without cement showed statistically better outcomes at 6 weeks for the AOFAS score. The EQ5D favored the press fit component at 6 weeks, 6 months and 1 year. For the AOS pain scale the 6 month results favored the press fit component, and for the difficulty scale the results favored the press fit components at 6 weeks and 1 year. Survivorship for all joint replacements (revision of metal components) was 96 percent for the total cohort, with 2 metal components in two ankles being revised, both in the cementless group (chi square not significant). Conclusion: As all outcomes to date favor press fit fixation there does not seem to be any need to augment fixation with cement in this total ankle design. There were two metal component revisions in the cementless group and one associated with loosening. There major are demographic differences between the groups and so an RCT would be required to correctly answer the question.

IMPROVEMENT OF DETAILS CONNECTION ASSEMBLY TECHNOLOGY WITH INTERFERENCE

2016 ◽  
Vol 1 (2) ◽  
pp. 30-34
Author(s):  
Коновалов ◽  
Vladimir Konovalov ◽  
Симанин ◽  
Nikolay Simanin ◽  
Петрова ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Hydraulic Cylinder ◽  
Machine Building ◽  
Technical Solution ◽  
Mechanical Assembly ◽  
Interference Fit ◽  
Press Fit ◽  
Axial Forces ◽  
The Press ◽  
Assembly Technology

The purpose of the study is to increase the strength of the collected compounds and to expand the technological accuracy of the method of Assembly with an interference fit. Fixed press-fit connection with interference are widely used in machine building, when the transfer of substantial axial forces are required, torques or combined loads from their joint action. Resistance to mutual misalignment of the parts in these compounds is created and supported by the forces of elastic deformation on the mating surface of the covered part (shaft) and stretching on the mating surfaces of the covering parts (holes) is proportional to the magnitude of the preload in the connection. In such compounds, the diameter of the shaft before Assembly is always larger than the diameter of the hole. In the article the analysis of the known different ways of joining parts with interference fit, including hydraulic presses. The second problem is solved due to the fact that the connection details with tightness is carried out by pressing the press stroke from one detail to another, and the breakdown of the compounds obtained by the relative longitudinal movement of parts, in which the breakdown is carried out periodically in the process of pushing through the transfer of force from the press stroke to pressed items to the elastic connection. The force on the press stroke is created by a hydraulic cylinder with large displacement, a resilient connection between the slider and pressed item performs in the cylinder, the fluid pressure and volume which can be adjusted by changing the stiffness and capacity of the drive RAM, as well as the magnitude of its longitudinal movement during the disruption. The scheme of Assembly of the connection de-hoist with tension. Original technical solution for press fit connection parts extends the technological possibilities of the equipment, increases the strength of the collected compounds and can be used in machine building, particularly in mechanical Assembly processes and, in particular, in the repair and production of agricultural machinery.

scholarly journals Characteristics of anteroposterior curvatures of the spine in soccer and futsal players

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Krystyna Chromik ◽  
Anna Burdukiewicz ◽  
Jadwiga Pietraszewska ◽  
Aleksandra Stachoń ◽  
Paweł Wolański ◽  
...  
Keyword(s):  
College Students ◽  
Statistical Analysis ◽  
Injury Prevention ◽  
Analysis Of Variance ◽  
Statistical Significance ◽  
Body Posture ◽  
Soccer Players ◽  
Prevention Training ◽  
The Difference ◽  
Post Hoc

AbstractPurpose. The aim of the study was to determine differences in anteroposterior spine curvatures between futsal players, soccer players, and non-training students. The results may contribute to the development of present-day knowledge of posturometry, and its implementation in training can help reduce the risk of body posture disorders in athletes. Methods. The examined group consisted of 48 athletes and 38 non-training college students. Body posture parameters were measured with the use of Posturometr-S. The normality of distribution was checked with the Shapiro-Wilk test, and the differences between the groups were measured with ANOVA and the Bonferroni post-hoc test. The level of statistical significance was set at p < 0.05. Results. The analysis of angle values revealed the widest and most similar measurements in the group of futsal players and soccer players. The analysis of variance proved statistically significant differences between the soccer players and futsal players (p = 0.003). The difference between the soccer players and non-training students was statistically significant. The highest γ angular value was measured in non-training students, followed by futsal players and soccer players. The statistical analysis revealed significant differences between the non-training students and futsal players, as well as non-training students and soccer players (p < 0.001). Conclusions. A complex assessment of athletes’ body posture is crucial in injury prevention. Training overloads may often lead to disorders of the organ of locomotion and affect the correct body posture in athletes. This, in turn, may result in pains and injuries.

Auszugverhalten von Schaftfräsern*/Pull-out behavior of end mills – Experimental study on different clamping devices with various clamping mechanisms

2018 ◽  
Vol 108 (05) ◽  
pp. 353-358
Author(s):  
E. Abele ◽  
F. Ali ◽  
M. Berger
Keyword(s):  
Experimental Study ◽  
Test Bench ◽  
Mechanical Load ◽  
Mechanisms Of Action ◽  
Heavy Duty ◽  
Press Fit ◽  
Pull Out ◽  
The Press ◽  
End Mills ◽  
Tool Position

Aus Schwerzerspanung und Turbinenschaufelfertigung ist bekannt, dass Werkzeuge aus dem Spannfutter ausgezogen werden. Die veränderte Werkzeugposition führt zur Abweichung von den vorgegebenen Toleranzen und einer geringeren Fertigungsqualität oder Beschädigung des Werkstücks. Der Artikel untersucht das Auszugsverhalten verschiedener Spannfutter. Mit einem Prüfstand können die Einflüsse der mechanischen Belastung und der Klemmlänge auf die Haltekraft im Pressverband betrachtet und die Wirkmechanismen beim Auszug des Werkzeuges aus dem Spannfutter sensorisch ermittelt werden. &nbsp; From heavy-duty cutting and turbine blade manufacturing it is known that tools pull out from chucks. A change in tool position leads to deviations from tolerance and decreases manufacturing quality or damages the workpiece. This article explores the extension behavior of different chucks on a specifically designed test bench. This allows determining how mechanical load and clamping length influence the holding force in the press fit and what mechanisms of action affect the extraction of the tool from the chuck.

Do longitudinal orthodontic trials use appropriate statistical analyses? A meta-epidemiological study

2021 ◽  
Author(s):  
Samer Mheissen ◽  
Haris Khan ◽  
Mohammed Almuzian ◽  
Emad Eddin Alzoubi ◽  
Nikolaos Pandis
Keyword(s):  
Statistical Analysis ◽  
Epidemiological Study ◽  
Data Extraction ◽  
Statistical Significance ◽  
Repeated Measure ◽  
Exact Test ◽  
Optimal Analysis ◽  
Study Characteristics ◽  
Measure Analysis ◽  
Repeated Measure Analysis

Summary Background In orthodontic trials, longitudinal designs with multiple outcome measurements over time are common. The aim of this epidemiological study was to examine whether optimal statistical analysis approaches have been used in longitudinal orthodontic trials. Methods Pubmed was searched in August 2021 for longitudinal orthodontic trials with at least three time points of outcome assessment published in the 2017–20 period. Study selection and data extraction were done independently and in duplicate. The analysis approaches undertaken were tabulated and associations between study characteristics and the use of optimal analysis or not were assessed using Fisher’s exact test and logistic regression. Results One hundred forty-seven out of 563 unique records were deemed eligible for inclusion. Only 26.50% of these trials used an optimal statistical analysis for longitudinal data where the data structure is accounted for. None of the study characteristics except the statistical significance of the results were associated with the appropriateness of the statistical analysis. The odds of significant results in studies with suboptimal analyses were higher than that in studies with optimal longitudinal analyses (odds ratio: 3.48, 95% confidence interval: 1.62, 7.46, P = 0.001). For the studies with optimal analysis, the most frequent test was repeated-measure analysis of variance (RM-ANOVA). The reporting of the statistical analysis section was suboptimal in the majority of the trials. Conclusion Most longitudinal orthodontic trials are not analysed using optimal statistical approaches. Inferences and interpretation of their results are likely to be compromised.

Wybrane parametry jakości ucisku i relaksacji klatki piersiowej wykonywanej przez personel pielęgniarski w ramach pozaszpitalnego nagłego zatrzymania krążenia ? badanie pilotażowe

2018 ◽  
Vol 21 (4) ◽  
Author(s):  
Paweł Więch ◽  
Marek Muster ◽  
Dariusz Bazaliński ◽  
Grzegorz Kucaba ◽  
Izabela Sałacińska ◽  
...  
Keyword(s):  
Health Care ◽  
Primary Health Care ◽  
Statistical Analysis ◽  
Discharge Rate ◽  
Statistical Significance ◽  
Sudden Cardiac Arrest ◽  
Initial Examination ◽  
Relaxation Parameters ◽  
Primary Health

Introduction. Sudden cardiac arrest (SCA) in out-of-hospital conditions is a frequent condition of immediate life-emergency of cardiological background. The survival and discharge rate in SCA patients treated by medical services is still at a low level. Aim. The aim of the study was to analyze selected parameters of the quality of chest compressions and relaxation performed by nursing staff as part of out-of-hospital SCA. Material and methods. The study covered a group of 48 nurses working in primary health care in branches of conservative (PRE/C = 24 people, mean age 33.04 ± 9.20) and surgery profile (PRE/I = 24 people, average age 31.88 ± 9.97), participating in the research project of the Center for Medical and Natural Sciences Research and Innovation, University of Rzeszów in Rzeszów. Two months after the initial examination and intervention, the test was repeated. The assessment of selected compression and relaxation parameters was performed using the True CPR Resuscitation Assistant. The statistical analysis of the collected material was carried out with the SPSS Statistics 20 software. The statistical analysis used the analysis of variables using parametric and non-parametric tests. The statistical significance was assumed at p < 0.05. Results. Initially, a high percentage of the effectiveness of the most important compression and relaxation parameters of the chest was obtained during 2-minute out-of-hospital cardiopulmonary resuscitation with no statistically significant differences between the two groups (PRE/C: 51 mm depth, 83.92% relaxation, frequency 115.46 vs. PRE/I: depth: 47.58 mm, relaxation: 92.54, frequency: 109.96, p < 0.05). After two months, similar parametric values were observed with no statistical significance (p < 0.05). Conclusions. The initial high quality of compressions and relaxation was found in nurses participating in the simulated out-of-hospital SCA, while there were no significant differences between primary health care nurses working at conservative departments and nurses from surgical ones. After a two-month interval from the initial examination and training, high CPR effectiveness was observed based on the guidelines of the European Resuscitation Council from 2015.

scholarly journals Three Evidence Based Methods to Compensate for a Lack of Subject Background when Ordering Chemistry Monographs

2008 ◽  
Vol 3 (3) ◽  
pp. 3
Author(s):  
Robert A. Wright
Keyword(s):  
Statistical Analysis ◽  
Statistical Significance ◽  
Evidence Base ◽  
Circulation Rate ◽  
Evidence Based ◽  
Practical Application ◽  
Present Evidence ◽  
Library System ◽  
Over Time ◽  
Selection Of

Objective – The aim of this article is to present evidence based methods for the selection of chemistry monographs, particularly for librarians lacking a background in chemistry. These methods will be described in detail, their practical application illustrated, and their efficacy tested by analyzing circulation data. Methods – Two hundred and ninety-five chemistry monographs were selected between 2005 and 2007 using rigorously-applied evidence based methods involving the Library's integrated library system (ILS), Google, and SciFinder Scholar. The average circulation rate of this group of monographs was compared to the average circulation rate of 254 chemistry monographs selected between 2002 and 2004 when the methods were not used or were in an incomplete state of development. Results – Circulations/month were on average 9% greater in the cohort of monographs selected with the rigorously-applied evidence based methods. Further statistical analysis, however, finds that this result can not be attributed to the different application of these methods. Conclusion – The methods discussed in this article appear to provide an evidence base for the selection of chemistry monographs, but their application does not change circulation rates in a statistically significant way. Further research is needed to determine if this lack of statistical significance is real or a product of the organic development and application of these methods over time, making definitive comparisons difficult.

scholarly journals Therapeutic Effect of Oral Administration and External Therapy of Traditional Chinese Medicine on Cervical Tuberculous

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Guoqiang Yang ◽  
Jin Zhang
Keyword(s):  
Statistical Analysis ◽  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Oral Administration ◽  
Total Effective Rate ◽  
Statistical Significance ◽  
Effective Rate ◽  
Control Group ◽  
Treatment Data ◽  
Experimental Group

Objective: To analyze the clinical effect and value of oral administration and external therapy of traditional Chinese medicine for treatment of cervical tuberculous lymphadenopathy. Methods: A total of 56 patients with cervical tuberculous lymphadenopathy admitted to our hospital from January 1 to January 2018 were recruited. By using double-blind method, the patients were divided into control group (n=28) and experimental group (n=28). Control group comprised of patients with conventional anti-tuberculosis treatment, while the experimental group comprised of patients treated with oral administration and external therapy of traditional Chinese medicine. Total effective rate, incidence of complication and level of T lymphocyte subsets were compared between the two groups of cervical tuberculous lymphadenopathy patients. Results: Post-treatment data of total effective rate, complication rate, CD3+, CD4+, CD8+, CD4+/CD8+ of the experimental group were compared with the control group. P<0.05; statistical analysis showed statistical significance. Post-treatment data of CD3+, CD4+, CD8+, CD4+/CD8+ of both control and experimental groups were compared with pre-treatment data. P<0.05; statistical analysis showed statistical significance. Conclusion: Oral administration and external therapy of traditional Chinese medicine possesses significant effect in treatment of cervical tuberculous lymphadenopathy.

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