Theoretical Analysis and Experimental Investigation on Buckling of FASTMast Deployable Structures

2015 ◽  
Vol 15 (05) ◽  
pp. 1450075 ◽  
Author(s):  
Yulong Jin ◽  
Tao Liu ◽  
Rongxin Lyu ◽  
Bin Ji ◽  
Qifeng Cui
Keyword(s):  
Theoretical Analysis ◽  
Solar Array ◽  
Joint Movement ◽  
Deployable Structures ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Euler Buckling ◽  
Deployable Structure ◽  
Research Findings ◽  
Stiffness Characteristics

FASTMast (Folding Articulated Square Truss Mast) deployable structure is the main bracing structure for the flexible solar array of the international space stations. This study investigates the buckling of FASTMast deployable structures. To this end, the buckling modes and the stiffness characteristics of this structure using the flex batten as an elastic bearing member were theoretically analyzed. The analytical results show that (1) the buckling mode of a FASTMast deployable structure is similar to the elbow joint movement failure when the stiffness of the flex batten is below a critical stiffness value. Once this critical stiffness is reached, the buckling mode takes on the form of Euler buckling. (2) The stiffness of the flex batten is proportional to its cross-sectional second moment of area. Furthermore, an experimental study was carried out to validate the accuracy of the theoretical analysis. The results from experimental work agree fairly well with those from theoretical analysis. The research findings herein are expected to be useful for future studies on similar structures.

scholarly journals A national cross-sectional survey of the attitudes, skills and use of evidence-based practice amongst Spanish osteopaths

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gerard Alvarez ◽  
Cristian Justribo ◽  
Tobias Sundberg ◽  
Oliver P. Thomson ◽  
Matthew J. Leach
Keyword(s):  
Evidence Based Practice ◽  
Evidence Based ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Professional Literature ◽  
Media Campaigns ◽  
Participant Engagement ◽  
Online Databases ◽  
Research Findings ◽  
Healthcare Professions

Abstract Background Although evidence-based practice (EBP) is largely supported across healthcare professions, its implementation in manual therapy professions such as osteopathy remains limited and debated. There is currently little knowledge of how Spanish osteopaths relate to EBP. Objectives The main aim of this study was to investigate the attitudes, skills and use of EBP among Spanish osteopaths. A secondary aim was to identify barriers and facilitators for the adoption of EBP in the Spanish osteopathic context. Methods National cross-sectional survey of Spanish osteopaths registered and non-registered to an osteopathic association in Spain. Eligible participants were invited by a range of recruitment strategies including email and social media campaigns to complete the Spanish-translated Evidence-Based practice Attitude and utilization Survey (EBASE) anonymously online. Results A total of 567 osteopaths completed the survey which represents an approximate response rate of 9%. Participant’s attitudes toward EBP were largely positive. Most respondents agreed or strongly agreed that EBP was necessary in the practice of osteopathy (89.6%) and that professional literature and research findings were useful to their day-to-day practice (88.9%). Levels of perceived skill in EBP were reported as low to moderate with lowest levels for items related to ‘research conduct’. Except reading/reviewing professional literature and using online search engines to find practice-related literature, participant engagement in all other EBP-related activities was generally infrequent. The perceived proportion of clinical practice that was based on clinical research evidence was reported to be very small. Main barriers to EBP uptake included a lack of clinical evidence in osteopathy and insufficient skills for applying research findings. Main facilitators of EBP uptake included access to full-text articles, internet at the workplace and online databases. Conclusions Spanish osteopaths were largely supportive of evidence-based practice, had low to moderate skills in EBP and engaged in EBP activities infrequently. Formal regulation of the profession in Spain and the inclusion of osteopathic programs into the university sector would potentially improve EBP skills and use.

scholarly journals Auditors, Underwriters, and Firm Owners’ Interaction in an IPO Environment: The Case of OECD Nations

2021 ◽  
Vol 13 (11) ◽  
pp. 6281
Author(s):  
Sheela Sundarasen ◽  
Kamilah Kamaludin ◽  
Izani Ibrahim ◽  
Usha Rajagopalan ◽  
Nevi Danila
Keyword(s):  
Positive Impact ◽  
Common Law ◽  
Civil Law ◽  
Least Square ◽  
Interactive Effects ◽  
Cross Sectional ◽  
Key Stakeholders ◽  
Research Findings ◽  
Firm Owners ◽  
The Relationship

This study explores the effects of interactions among key stakeholders, i.e., auditors, underwriters, and firm owners on IPOs’ first-day returns in selected OECD nations. It also examines the alteration effects of legal origin (Common law and Civil law) on the relationship between the interacted key stakeholders and IPOs’ first-day returns. A total of four thousand one hundred and sixty-four IPOs from twenty-eight OECD nations are included in this study. Since it is cross-sectional data, a two-stage least square regression is applied. The empirical outcomes indicate that, in general, the interacted reputable underwriters and auditors have a positive impact on IPOs’ first-day return. The relationship is modified between common law and civil law nations, whereby in civil law nations, no significance is demonstrated except for the interaction between the reputable auditors and underwriters. In the common law nation, interactions between reputable auditors and ownership retention have an impact on IPOs’ first-day return. The research findings provide outlooks into an IPO framework for issuers, investors, and regulators. Issuers may want to weigh carefully the costs and benefits of hiring credible auditors and underwriters when going public as they act as signaling agents. As for the investors, they should take into consideration the involvement of reputable underwriters and auditors and the degree to which the IPO firms retain ownership, as the interactive effects give clear signals on firm valuation and IPOs’ first-day returns. Regulators may find the findings informative concerning the creation of a more organized regulatory and financial system that could lead to a deeper and more open financial market.

Experience sampling research in psychopathology: opening the black box of daily life

2009 ◽  
Vol 39 (9) ◽  
pp. 1533-1547 ◽  
Author(s):  
I. Myin-Germeys ◽  
M. Oorschot ◽  
D. Collip ◽  
J. Lataster ◽  
P. Delespaul ◽  
...  
Keyword(s):  
Daily Life ◽  
Experience Sampling ◽  
Added Value ◽  
Cross Sectional ◽  
Gene Environment ◽  
Psychological Models ◽  
Research Findings ◽  
Underlying Mechanisms ◽  
New Research ◽  
Momentary Assessment

A growing body of research suggests that momentary assessment technologies that sample experiences in the context of daily life constitute a useful and productive approach in the study of behavioural phenotypes and a powerful addition to mainstream cross-sectional research paradigms. Momentary assessment strategies for psychopathology are described, together with a comprehensive review of research findings illustrating the added value of daily life research for the study of (1) phenomenology, (2) aetiology, (3) psychological models, (4) biological mechanisms, (5) treatment and (6) gene–environment interactions in psychopathology. Overall, this review shows that variability over time and dynamic patterns of reactivity to the environment are essential features of psychopathological experiences that need to be captured for a better understanding of their phenomenology and underlying mechanisms. The Experience Sampling Method (ESM) allows us to capture the film rather than a snapshot of daily life reality of patients, fuelling new research into the gene–environment–experience interplay underlying psychopathology and its treatment.

scholarly journals Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel

2018 ◽  
Vol 191 ◽  
pp. 00008
Author(s):  
Ikram Feddal ◽  
Abdellatif Khamlichi ◽  
Koutaiba Ameziane
Keyword(s):  
Stiffened Panel ◽  
Buckling Mode ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Stiffened Panels ◽  
Specific Strength ◽  
Euler Buckling ◽  
Buckling Behavior ◽  
Composite Stiffened Panel ◽  
Strength And Stiffness

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.

scholarly journals Willingness to Participate in Vaccine-Related Clinical Trials among Older Adults

2018 ◽  
Vol 15 (8) ◽  
pp. 1743 ◽  
Author(s):  
Divyanshu Raheja ◽  
Evelyn Davila ◽  
Eric Johnson ◽  
Rijalda Deović ◽  
Michele Paine ◽  
...  
Keyword(s):  
Older Adults ◽  
Clinical Trials ◽  
Clinical Research ◽  
Elderly Person ◽  
The Elderly ◽  
Cross Sectional Study ◽  
Willingness To Participate ◽  
Cross Sectional ◽  
Convenience Sample ◽  
Research Findings

The purpose of this study is to understand among a convenience sample of 400 adults aged 60 years of age or older (1) reasons for being willing or unwilling to participate in a vaccine clinical research study and (2) overall perceptions about vaccine clinical research. A cross-sectional study using a sample of older adults residing in the metro-Atlanta area and surrounding neighborhoods was conducted. The study questionnaire contained 37 questions, including questions about socio-demographics and perceptions about clinical trial processes. Statistical analysis was conducted using logistic regression. The adjusted modeling results indicated that sex, distance to research clinic, and being informed about the research findings played a role in the likelihood of an elderly person participating in a vaccine study. Males were more likely to participate in clinical trials as compared to females (OR: 2.486; CI: 1.042–5.934). Most participants were willing to travel up to 25 miles from the research clinic. Of the respondents, 45% were unlikely to participate if the results of the current trial are not shared. Improving access to clinical trials in terms of distance traveled and ensuring streamlined processes to inform participants about the results of the trial in the future would increase willingness to participate in vaccine clinical trials. The survey could serve as a useful tool for conducting vaccine studies and other clinical trials by understanding the barriers specific to the elderly.

scholarly journals Multi-configuration Stiffened Panels under Compressive Load: Part 1 – Theoretical Analysis

2018 ◽  
Vol 7 (3.11) ◽  
pp. 38
Author(s):  
Ramzyzan Ramly ◽  
Wahyu Kuntjoro ◽  
Amir Radzi Abdul Ghani ◽  
Rizal Effendy Mohd Nasir ◽  
Zulkifli Muhammad
Keyword(s):  
Theoretical Analysis ◽  
Experimental Analysis ◽  
Critical Loads ◽  
Input Parameter ◽  
Compressive Loading ◽  
Compressive Load ◽  
Cross Sectional ◽  
Stiffened Panels ◽  
Compression Load ◽  
Main Input

Stiffened panels are the structure used in the aircraft wing skin panels. Stiffened panels are often critical in compression load due to its thin structural configuration. This paper analyzes the critical loads of a multi configuration stiffened panels under axial compressive loading. The study comprised three main sections; theoretical analysis, numerical analysis and experimental analysis. The present paper deals only with the theoretical analysis. This first part of analysis is very important since the results will be the main input parameter for the subsequent numerical and experimental analysis. The analysis was done on the buckling properties of the panels. Four panel configurations were investigated. Results showed that even though the stiffened panels have the same cross-sectional area, their critical loads were not identical.   

Buckling of Thin-Walled Long Steel Cylinders Subjected to Bending

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Sotiria Houliara ◽  
Spyros A. Karamanos
Keyword(s):  
Structural Response ◽  
Cylinder Wall ◽  
Imperfection Sensitivity ◽  
Bifurcation Instability ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Moment Capacity ◽  
Thin Walled ◽  
Cylindrical Steel ◽  
Element Technique

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique, the bifurcation moment is calculated, the post-buckling response is determined, and the imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model that considers the ovalized prebuckling configuration and results in very useful closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is thoroughly examined and discussed, considering the framework of the provisions of the new European Standard EN1993-1-6.

Ruga mechanics of soft-orifice closure under external pressure

2021 ◽  
Vol 477 (2249) ◽  
Author(s):  
Hanxun Jin ◽  
Alexander K. Landauer ◽  
Kyung-Suk Kim
Keyword(s):  
Surface Layer ◽  
Limit Load ◽  
Phase Evolution ◽  
External Pressure ◽  
Soft Material ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Threefold Symmetry ◽  
Instability Modes ◽  
Symmetry Mode

Here, we report the closure resistance of a soft-material bilayer orifice increases against external pressure, along with ruga-phase evolution, in contrast to the conventional predictions of the matrix-free cylindrical-shell buckling pressure. Experiments demonstrate that the generic soft-material orifice creases in a threefold symmetry at a limit-load pressure of p / μ  ≈ 1.20, where μ is the shear modulus. Once the creasing initiates, the triple crease wings gradually grow as the pressure increases until the orifice completely closes at p / μ  ≈ 3.0. By contrast, a stiff-surface bilayer orifice initially wrinkles with a multifold symmetry mode and subsequently develops ruga-phase evolution, progressively reducing the orifice cross-sectional area as pressure increases. The buckling-initiation mode is determined by the layer's thickness and stiffness, and the pressure by two types of the layer's instability modes—the surface-layer-wrinkling mode for a compliant and the ring-buckling mode for a stiff layer. The ring-buckling mode tends to set the twofold symmetry for the entire post-buckling closure process, while the high-frequency surface-layer-wrinkling mode evolves with successive symmetry breaking to a final closure configuration of two- or threefold symmetry. Finally, we found that the threefold symmetry mode for the entire closure process provides the orifice's strongest closure resistance, and human saphenous veins remarkably follow this threefold symmetry ruga evolution pathway.

On the Buckling of Certain Optimum Plate Structures with Linearly Varying Thickness

1959 ◽  
Vol 10 (2) ◽  
pp. 145-148 ◽  
Author(s):  
E. H. Mansfield
Keyword(s):  
Local Buckling ◽  
Constant Thickness ◽  
Sectional Area ◽  
Longitudinal Compression ◽  
Cross Sectional ◽  
Plate Structures ◽  
Buckling Loads ◽  
Simply Supported ◽  
Euler Buckling ◽  
Varying Thickness

SummaryThis paper is concerned with the buckling under uniform longitudinal compression of a variety of structures composed of plates whose thickness tapers linearly to zero across the section. Such structures include the angle of Fig. 1, the strut of cruciform section of Fig. 2 and the simply-supported strip of Fig. 3. For given cross-sectional area and overall dimensions (e.g. length of arm) the sections with linearly varying thickness achieve a greater buckling load (assuming that local buckling, rather than Euler buckling, is the criterion) than sections with any other smooth variation of thickness. These particular sections are therefore optimum sections and, even if they may not be used in practice, provide a convenient yardstick for purposes of comparison. The buckling loads are considerably greater than those for the corresponding “constant thickness” sections.

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