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Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and material properties more efficiently. Due to the large variety of design variables, for example laminate layup in composite structures, a prohibitively large number of tests would be required for experimental assessment, and thus reliable numerical techniques are of particular interest. The purpose of this paper is to analyze different methods of numerical buckling load estimation, formulate simulation procedures suitable for commercial software and give recommendations regarding their application. All investigations have been carried out for cylindrical composite shells; however similar approaches are feasible for other structures as well.

The authors develop a concept to apply artificial load imperfections with the aim to estimate as good as possible lower bounds for the buckling loads of shells for which the actual physical imperfections are not known. Single and triple perturbation load approach, global and local dynamic perturbation approach and path following techniques are applied to the analysis of a cylindrical composite shell with known buckling characteristics. Results of simulations are compared with published experimental data.

A single perturbation load approach is reproduced and modified. Buckling behavior for negative values of the perturbation load is examined and a pattern similar to a positive perturbation load is observed. Simulations with three perturbation forces show a decreased (i. e. more critical) value of the buckling load compared to the single perturbation load approach. Global and local dynamic perturbation approaches exhibit a behavior suitable for lower bound estimation for structures with arbitrary geometries.

Various load imperfection approaches to buckling load estimation are validated and compared. All investigated methods do not require knowledge of the real geometrical imperfections of the structure. Simulations were performed using a commercial finite element code. Investigations of sensitivity with respect to a single perturbation load are extended to the negative range of the perturbation load amplitude. A specific pattern for a global perturbation approach was developed, and based on it a novel simulation procedure is proposed.

When a thick structure is, on the contrary, subjected to moisture absorption, a fairly long time may be needed to reach full saturation. It is, therefore, important to understand and predict the areas of complex composite structures that are more prone to saturation. The material knock-down factors (proportional to the moisture content) may be applied only to these zones, in order to obtain a less pessimistic structural response prediction. The purpose of this paper is to investigate an FE diffusion model that was used to validate the absorption testing results of thick carbon epoxy laminates.

The experimental results were validated by using a diffusion model in Abaqus FE code.

The absorption results of three 15 mm thick carbon epoxy laminates are presented and reproduced via a mass diffusion model. The laminates were conditioned at 70°C and 85 per cent relative humidity in a moisture chamber. Areas more prone to saturation have been predicted by the FE model and the moisture content in the non-saturated areas has been calculated.

The practical implications of the absorption model are discussed on an example of an aero-engine fan blade-like structure.

Validation of thick panels’ absorption data is an important point of novelty of this paper, given the lack of experimental and modelling validation in the open literature.

The objective of this paper is to investigate numerically the buckling behavior of submersible composite cylinders.

By means of FEM and golden section method, the search of hoop winding layers, longitudinal winding layers and helical winding layers are studied to optimize the buckling pressure. Considering the mid-strengthening cylinder, the size and distribution of stiffeners are studied systematically.

The results show that laying the hoop winding layers in the two outer sidewalls and the longitudinal winding layers in the middle of the shell is helpful to increase the buckling pressure, and the optimal helical winding angle changes with slenderness ratio.

For mid-strengthening cylinder, the effect of helical winding angle of stiffener on buckling pressure becomes weak gradually with the increase of stiffener thickness. With the increasing of the spacing between stiffeners, the buckling pressure increases first and decreases later. What is more, the mid-strengthening cylinder is less sensitive to the initial geometric imperfections than unstiffened shells.

The purpose of this paper is to derive knockdown factor functions in terms of a shell thickness ratio (i.e. the ratio of radius to thickness) for conventional orthogrid and hybrid-grid stiffened cylinders for the lightweight design of space launch vehicles.

The shell knockdown factors of grid-stiffened cylinders under axial compressive loads are derived numerically considering various shell thickness ratios. Two grid systems using stiffeners – conventional orthogrid and hybrid-grid systems – are used for the grid-stiffened cylinders. The hybrid-grid stiffened cylinder uses major and minor stiffeners having two different cross-sectional areas. For modeling grid-stiffened cylinders with various thickness ratios, the effective thickness (t_eff) of the cylinders is kept constant, and the radius of the cylinder is varied. Thickness ratios of 100, 192 and 300 are considered for the orthogrid stiffened cylinder, and 100, 160, 200 and 300 for the hybrid-grid stiffened cylinder. Postbuckling analyses of grid-stiffened cylinders are conducted using a commercial nonlinear finite element analysis code, ABAQUS, to derive the shell knockdown factor. The single perturbation load approach is applied to represent the geometrical initial imperfection of a cylinder. Knockdown factors are derived for both the conventional orthogrid and hybrid-grid stiffened cylinders for different shell thickness ratios. Knockdown factor functions in terms of shell thickness ratio are obtained by curve fitting with the derived shell knockdown factors for the two grid-stiffened cylinders.

For the two grid-stiffened cylinders, the derived shell knockdown factors are all higher than the previous NASA’s shell knockdown factors for various shell thickness ratios, ranging from 100 to 400. Therefore, the shell knockdown factors derived in this study may facilitate in the development of lightweight structures of space launch vehicles from the aspect of buckling design. For different shell thickness ratios of up to 500, the knockdown factor of the hybrid-grid stiffened cylinder is higher than that of the conventional orthogrid stiffened cylinder. Therefore, it is concluded that the hybrid-grid stiffened cylinder is more efficient than the conventional orthogrid-stiffened cylinder from the perspective of buckling design.

The obtained knockdown factor functions may provide the design criteria for lightweight cylindrical structures of space launch vehicles.

Derivation of shell knockdown factors of hybrid-grid stiffened cylinders considering various shell thickness ratios is attempted for the first time in this study.

The purpose of this paper is to present the probabilistic approach to a new robustness-based design strategy for thin-walled composite structures in post-buckling.

Because inherent uncertainties in geometry, material properties, ply orientation and thickness affect the structural performance and robustness, these variations are taken into account.

The methodology is demonstrated for the sake of simplicity with an unstiffened composite plate under compressive loading, and the probabilistic and deterministic results are compared. In this context, the structural energy and uncertainties are employed to investigate the robustness and reliability of thin-walled composite structures in post-buckling.

As practical implication, the methodology can be extended to stiffened shells, widely used in aerospace design with the aim to satisfy weight, strength and robustness requirements. Moreover, a new argument is strengthened to accept the collapse close to ultimate load once robustness is ensured with a required reliability.

This innovative strategy embedded in a probabilistic framework might lead to a different design selection when compared to a deterministic approach, or an approach that only accounts for the ultimate load. Moreover, robustness measures are redefined in the context of a probabilistic design.

This paper aims to present a new robustness-based design strategy for thin-walled composite structures under compressive loading, which combines strength requirements in terms of the limit and ultimate load with robustness requirements evaluated from the structural energy until collapse.

In order to assess the structural energy, the area under the load-shortening curve between several characteristic points such as local buckling, global buckling, onset of degradation and collapse load is calculated. In this context, a geometrically nonlinear finite element analysis is carried out, in which the ply properties are selectively degraded by progressive failure.

The advantage of the proposed methodology is observed by analyzing unstiffened composite plates under compressive loading, wherein the lightest plate that satisfies both strength and robustness requirements can be attained.

As a practical implication, this methodology gives a new argument to accept the collapse load close to the ultimate load once robustness is ensured.

The structural energy is employed to investigate the robustness of thin-walled composite structures in postbuckling, and new energy-based robustness measures are proposed. In the design of composite structures, this innovative strategy might lead to a more robust design when compared to an approach that only accounts for the ultimate load.

In September 1963 the Federal Government of Malaysia announced its intention to encourage the establishment of an automobile industry. It was felt that car manufacture would underpin the industrialisation of the country. However, it was not until 1967 that assembly of cars commenced in Malaysia, with the help of Swedish partners. Simultaneously, the government imposed high tariffs on car imports; CBUs or completely built‐up cars in the jargon. Stringent import licensing was enforced to encourage the growth of local assembly of imported packs of CKD (completely knocked down) vehicles. Since then, the Malaysian automobile industry has grown steadily, helped by strong growth of the national economy and relatively low labour costs. Despite this latter advantage, the small scale of the industry (on a global comparison) militates against achieving really competitive production costs. The government's insistence since 1979 in progressively cutting the proportion of imported components in CKD vehicles has not helped in this respect, since the Malaysian component industry is still small‐scale and therefore high cost. Indeed, the government has made clear its intention that all vehicles shall eventually be CML (completely made locally).

This study sheds light on the complex relationship between international diversification and firm performance and explores whether future performance expectations seem to drive managerial decisions related to internationalization issues.

We conducted in-depth investigation of five firms. This qualitative approach is allegedly better equipped to uncover the peculiarities of specific internationalization decisions by individual companies and the performance consequences derived from modifications in the degree of international diversification, which might go unnoticed in large-sample statistical analyses.

In line with Hennart’s (2007, 2011) and Verbeke and Brugman’s (2009) theoretical arguments, our findings indicate that no universal relationship should be expected between international diversification and firm performance. Rather, the performance consequences of internationalization-related decisions depend on the particular combinations of a firm’s characteristics and environment contingencies. Given managerial discretion, internationalization decisions would not be randomly made, but rather would be endogenous, and, as such, the relationship between multinationality and performance can only be understood if one takes a contingent approach. Additionally, internationalization decisions seem to be taken within a context of uncertainty regarding the future, which suggests that managers seem to approach internationalization with a long-term perspective and may in fact be “buying real options.”

This study examined only five cases and they all relate to a particular type of firm: all are headquartered in a large emerging market with good domestic growth prospects, and each either is the leader or stands among the largest in its industry in the domestic market. While this relative homogeneity in the selection of the cases minimizes confounding factors, it suggests that findings may be specific to this particular (firm and market) context.

Managers should be aware that decisions that modify the international configuration of a firm might have distinct implications across different firms, given the particular (firm, industry, and environment) contingencies. Therefore, no universal normative orientation should be expected between international diversification and performance.

Although it is often implicitly assumed that managers make (informed) decisions with the objective of improving their firms’ (long-run) performance, there has been little discussion as to whether managers have detailed information about the expected performance implications arising from decisions that change the degree of international diversification of their firm and whether such decisions are driven by expected performance outcomes.

Examines the success factors critical to the adoption and implementation of advanced manufacturing technology. Empirically tests the hypothesis that the management variables most associated with the human factor in automation projects alone can differentiate firms who are successful in adopting the technologies from those who are not so successful. Analyzes the differences between the two groups of firms across 27 management variables and six demographic variables.