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Article

A. Sellitto, R. Borrelli, F. Caputo, A. Riccio and F. Scaramuzzino

The purpose of this paper is to investigate on the behaviour of a delaminated stiffened panel; the delamination growth is simulated via fracture elements implemented in…

Abstract

Purpose

The purpose of this paper is to investigate on the behaviour of a delaminated stiffened panel; the delamination growth is simulated via fracture elements implemented in B2000++® code based on the Modified Virtual Crack Closure Technique (MVCCT), matrix cracking and fibre failure have been also taken into account.

Design/methodology/approach

In order to correctly apply the MVCCT on the delamination front a very fine three-dimensional (3D) mesh is required very close to the delaminated area, while a 2D-shell model has been employed for the areas of minor interest. In order to couple the shell domain to the solid one, shell-to-solid coupling elements based on kinematic constraints have been used.

Findings

Results obtained with the global/local approach are in good correlation with those obtained with experimental results.

Originality/value

The global/local approach based on kinematic coupling elements in conjunction with fracture elements allows to investigate and predict the behaviour of a stiffened delaminated composite panel in an efficient and effective way.

Details

International Journal of Structural Integrity, vol. 5 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

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Article

A. Sellitto, R. Borrelli, F. Caputo, A. Riccio and F. Scaramuzzino

The purpose of this paper is to investigate and to assess the capabilities of the most common finite element (FE)‐based tools to deal with global‐local analysis. Two kinds…

Abstract

Purpose

The purpose of this paper is to investigate and to assess the capabilities of the most common finite element (FE)‐based tools to deal with global‐local analysis. Two kinds of coupling were investigated: shell to shell and shell to solid.

Design/methodology/approach

The issue of connecting non‐matching FE global and local models, characterized by different mesh refinements and/or different element types, was addressed by introducing appropriate kinematic constraints on the nodes at the interfaces. The coupling techniques available in the three FE‐based codes (ABAQUS®, NASTRAN® and ANSYS®), were assessed by applying them on a common numerical test case (non‐linear buckling analysis of a square plate). Results of the global‐local simulations were compared to the results obtained for relevant reference solutions.

Findings

The continuity of displacements and stresses across the interface between global and local models and the influence of the presence of the local model on the global model solution were used as parameters to test the quality of the results. It was observed that the tools implemented in the different codes provide different results. The results characterized by a higher quality were found by using the Multi Point Constraint available in ABAQUS®.

Originality/value

When dealing with complex structures, multi‐scale (global‐local) approaches are commonly adopted to optimize the computational cost by increasing mesh refinements and/or introducing elements with different formulations in specific region of the structures identified as “local model”. In this paper an overview of the coupling tools available in the main commercial FE code is given.

Details

International Journal of Structural Integrity, vol. 3 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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Article

Vladimir Kobelev

The purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main…

Abstract

Purpose

The purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main attention is paid to establishing of closed-form mathematical solutions for models of wings with coupling effects. Simplified solutions for calculating the divergence speed of wings with different geometry are established.

Design/methodology/approach

The wings are modeled as anisotropic plate elements and thin-walled beams with closed cross-section. Two-dimensional plate-like models are applied to analysis and design problems for wings of large aspect ratio.

Findings

At first, the equations of elastic deformation for anisotropic slender, plate-like wing with the large aspect ratio are studied. The principal consideration is delivered to the coupled torsion-bending effects. The influence of anisotropic tailoring on the critical divergence speed of the wing is examined in closed form. At second, the method is extended to study the behavior of the large aspect ratio, anisotropic wing with box-like wings. The static equations of the wing with box-like profile are derived using the theory of anisotropic thin-walled beams with closed cross-section. The solutions for forward-swept wing with box-like profiles are given in analytical formulas. The formulas for critical divergence speed demonstrate the dependency upon cross-sectional shape characteristics and anisotropic properties of the wing.

Research limitations/implications

The following simplifications are used: the simplified aerodynamic theory for the wings of large aspect ratio was applied; the static aeroelastic instability is considered (divergence); according to standard component methodology, only the component of wing was modeled, but not the whole aircraft; the simplified theories (plate-lime model for flat section or thin-walled beam of closed-section) were applied; and a single parameter that defines the rotation of a stack of single layers over the face of the wing.

Practical implications

The simple, closed-form formulas for an estimation of critical static divergence are derived. The formulas are intended for use in designing of sport aircraft, gliders and small unmanned aircraft (drones). No complex analysis of airflow and advanced structural and aerodynamic models is necessary. The expression for chord length over the span of the wing allows for accounting a board class of wing shapes.

Social implications

The derived theory facilitates the use of composite materials for popular small-size aircraft, and particularly, for drones and gliders.

Originality/value

The closed-form solutions for thin-walled beams in steady gas flow are delivered in closed form. The explicit formulas for slender wings with variable chord and stiffness along the wing span are derived.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

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Article

Rosario Borrelli, Francesco Di Caprio, Umberto Mercurio and Fulvio Romano

The main objective of this work is to assess the current capabilities of different commercial finite element (FE) codes in simulating the progressive damage of composite…

Abstract

Purpose

The main objective of this work is to assess the current capabilities of different commercial finite element (FE) codes in simulating the progressive damage of composite structures under quasi-static loading condition in post-buckling regime.

Design/methodology/approach

Progressive failure analysis (PFA) methodologies, available in the investigated FE codes, were applied to a simple test case extracted from literature consisting in a holed composite plate loaded in compression.

Findings

Results of the simulations are significantly affected by the characteristic parameters needed to feed the degradation models implemented in each code. Such parameters, which often do not have a physical meaning, have to be necessarily set upon fitting activity with an experimental database at coupon level. Concerning the test case, all the codes were found able to capture the buckling load and the failure load with a good accuracy.

Originality/value

This paper would to give an insight into the PFA capabilities of different FE codes, providing the guidelines for setting the degradation model parameters which are of major interest.

Details

International Journal of Structural Integrity, vol. 4 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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Book part

Jacques Defourny and Victor Pestoff

There is still no universal definition of the third sector in Europe, but it can be seen as including all types of non-governmental not-for-profit entities such as…

Abstract

There is still no universal definition of the third sector in Europe, but it can be seen as including all types of non-governmental not-for-profit entities such as non-profit organizations, mutuals, cooperatives, social enterprises and foundations. This article attempts to make sense of the current shifting conceptualization of the third sector in Europe. It is based on short country summaries of the images and concepts of the third sector in 13 European countries by EMES Network’s members, first presented in 2008 (Defourny and Pestoff, 2008; nine of them were recently revised and are found in the appendix to this article.). The perception and development of the third sector in Europe is closely related to the other major social governance institutions/mechanisms, like the market, state and community and through the third sector’s interaction with them. Moreover, many third sector organizations (TSOs) overlap with these other social institutions, resulting in varying degrees of hybridity and internal tensions experienced by them. TSOs can generate resources from their activities on the market, by providing services in partnership with the state and/or by promoting the interests of a given community or group. The country overviews document a growing professionalization of TSOs in most countries and a growing dependency of public funds to provide services. This has important theoretical and practical implications for orienting the articles included in this book. Thus, it can provide a key for better understanding the discussion and analysis in the remainder of this volume.

Details

Accountability and Social Accounting for Social and Non-Profit Organizations
Type: Book
ISBN: 978-1-78441-004-9

Keywords

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Article

Deniz Tunçalp and Patrick L. Lê

The purpose of this paper is to systematically review online ethnography and its boundary challenges. The paper especially focusses on how researchers draw space…

Abstract

Purpose

The purpose of this paper is to systematically review online ethnography and its boundary challenges. The paper especially focusses on how researchers draw space boundaries, set time boundaries and engage their online field.

Design/methodology/approach

The authors perform a systematic review of extant literature and identify 59 papers in 40 different journals as online ethnographies from various management disciplines. The authors perform both qualitative and quantitative analyses on papers in the sample.

Findings

The paper identifies how online ethnographers both define boundaries and engage their online field. The paper shows that some of the advantages of online ethnography actually prompt researchers to favor-specific research designs over others.

Research limitations/implications

The authors only focussed on articles adopting online ethnography in organization and management studies that are listed in Social Sciences Citation Index database. Online ethnographies in other research fields and indexes are not studied in this paper.

Practical implications

The paper makes suggestions on how to complement existing online ethnographies to reach a more comprehensive practice of online ethnography.

Social implications

The systematic review may help researchers to locate useful online ethnography examples across various management disciplines and may contribute to the maturation of online ethnography.

Originality/value

The paper synthesizes emerging trends in online ethnography and identifies how specific advantages actually prompt online ethnographers to limit themselves in their research designs.

Details

Journal of Organizational Ethnography, vol. 3 no. 1
Type: Research Article
ISSN: 2046-6749

Keywords

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Article

Aukse Endriulaitiene, Aurelija Stelmokiene, Giedre Geneviciute-Janoniene, Loreta Gustainiene, Gabija Jarasiunaite and Loreta Buksnyte-Marmiene

The purpose of this paper is to investigate how perceived leadership effectiveness is related to staff members’ attitudes towards development of elderly care organizations…

Abstract

Purpose

The purpose of this paper is to investigate how perceived leadership effectiveness is related to staff members’ attitudes towards development of elderly care organizations in private and public institutions.

Design/methodology/approach

A cross-sectional quantitative survey was conducted using self-report questionnaire that contained Modified Leadership Effectiveness Questionnaire (Heck et al., 2000), the scale of attitude towards change from Preziosi’s Organizational Diagnosis Model (1980) and organizational development intentions measure developed for the study. The respondents were 510 Lithuanian social workers and other staff members employed in different public and private elderly care organizations.

Findings

The results revealed that perceived higher leadership effectiveness was associated with more positive employees’ judgements on organization’s readiness to change both in private and public sector elderly care organizations. But perceived leadership effectiveness was not associated with staff members’ intentions to change. Also it was found that different models for private and public sector that explained the importance of particular leadership behaviours in the prediction of employees’ judgements on organizational change and intentions to change were valid.

Originality/value

This study may add to further broaden knowledge on attitudes of staff members towards development of elderly care organization and the role of leadership effectiveness taking into account the type of organization.

Details

International Journal of Public Leadership, vol. 13 no. 1
Type: Research Article
ISSN: 2056-4929

Keywords

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