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This paper presents a case study on the problem of loading air containers in air express carriers motivated from DHL and Air Hong Kong. The problem is to determine the containers to be loaded and the locations of the loaded containers in an aircraft while maintaining stability of the aircraft. The objective of the problem is to maximize the revenue obtained from delivering containers. We present an integer programming model to represent and optimally solve the problem. Computational experiments done on a number of randomly generated test instances show that the integer program can be a viable tool for generating loading plans in the companies since optimal or near-optimal solutions for the test instances are obtained within a reasonable amount of computation time.

The problem of optimal design of pressure vessel heads to maximize limit load behaviour is presented. Incremental elasto‐plastic analysis is used and a formulation based on the finite element method is presented whereby an approximate design model is generated which can be optimized via sequential programming. Results are presented for torispherical head shapes and tables are provided in order to evaluate the influence of different geometrical forms on limiting pressure loads. The method is generally applicable and can be applied to the design of components which are required to exhibit limited plastification under increasing load.

This paper aims to address the influence of lubrication methods on operational characteristics, power losses and temperature behavior of gears and bearings. It contributes to the improvement of resource and energy efficiency of geared transmissions.

Experimental investigations were performed at a gear and bearing power loss test rig. Thereby, dip lubrication, injection lubrication with injection volumes from 0.05 to 2.00 l/min and minimum quantity (MQ) lubrication with an injection volume as little as 28 ml/h were considered. Measurements were evaluated in terms of no-load and load-dependent power loss, bulk temperatures and mean gear coefficients of friction.

Results show strongly reduced no-load gear and bearing losses for lubrication methods with low lubricant quantities. Load-dependent losses are similar to conventional lubrication methods and tend to be lower at high speed. This is related to higher bulk temperatures, as the heat dissipation of lubrication methods with low oil quantities is limited. Limited thermal load limits were shown to be extended by LowLoss gears.

Systematic investigations were conducted to evaluate the influence of dip, injection and MQ lubrication on power loss and temperature behavior of gears and bearings. The results of this study support further research on needs-based lubrication methods for gearboxes.

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.

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THERE are so many different considerations to bo kept in mind in connexion with the manœuvring load factor requirements that it might be well to begin by listing the most important of these, as follows:

The aim of this review study is to present useful and practical expressions to compute the design vertical actions on load-bearing columns/walls of typical building structures on the basis of EN 1991: Eurocode 1.

It is derived by a typical case in which wind actions, snow actions and permanents actions are loading a roof construction. The results are finally used to calculate the loading on columns/walls. Both ultimate limit state and serviceability limit state are considered.

From an instructive point of view, the advantage of this method is that it is simplified, general, not time-consuming, and it can be standardised to typical building structures.

A number of example applications are introduced to illustrate the calculation procedure.

From an educational point of view, this problem is of interest to civil engineering students because the reviewed method is not cumbersome or time-consuming.

From an engineering educational point of view, this problem is of interest to civil engineering students because the reviewed method is not cumbersome or time-consuming.

New formulated expressions to calculate the loadings on structural membranes based on Eurocode are presented.

Poly‐ether‐ether‐ketone (PEEK), a specialty polymer, does not have any tribo‐utility as a bearing material in a virgin form since it exhibits quite a high coefficient of friction (μ) and stick‐slip behavior. The present paper seeks to deal with the adhesive wear behavior of series of PEEK composites based on inclusion of short fibers of glass (GF) and carbon (CF) and solid lubricants such as Polytetrafluoroethylene and graphite. The studies are focused to examine the role of these ingredients on enhancing PV limit, which is an indication of utility of a tribo‐polymer in severe operating conditions.

The Adhesive wear studies were performed on a pin on disc machine fabricated for high speed, load and temperature conditions. A composite pin slid over a disc of mild steel under two selected sliding speeds (2 and 3 m/s) for an hour. The load was varied in each experiment till the pin showed failure. The performance assessment was done based on multiple parameters such as magnitude of μ and its fluctuations with time, specific wear rate, PV limit, compatibility with the counterface, etc. PV limit was judged by observing either sudden increase in μ or wear rate (or both), deformation of the pin or change in the color of the disc.

It was observed that the neat PEEK exhibited very high and fluctuating μ with very low P‐V limit value (150 Nm/s) and high wear rate (2 × 10⁻¹⁴ m³/Nm). Inclusion of 30 percent CF benefited the strength properties but not the tribo‐performance appreciably. Composite D with a combination of GF (25 percent) and solid lubricants (30 percent) excelled in performance with a wide margin. The highest PV limit along with the lowest μ and lowest wear rate and counterface friendliness proved it to be most promising bearing material for the selected harsh operating conditions.

The composite D, which worked better than the commercial composite in almost all the selected operating conditions, indicates its commercial potential as a bearing grade material for high PV conditions.

Synergism between reinforcement and solid lubricants in right amount led to excellent friction and wear performance which was very well analysed based on worn surface topography.

A method is presented by which elastoplastic constitutive relations for the solid material equivalent to a perforated plate can be obtained, by performing numerical experiments employing the finite element method. The method is applied to a plate of elastic‐perfectly plastic material, perforated in an equilateral triangular penetration pattern of circular holes. The following situations are considered: plane stress, as existing in thin plates under in‐plane loading, generalized plane strain, which approximates the behaviour of thick plates subjected to in‐plane loading and the plate bending condition. First results have been obtained for the plane stress situation. These results show that, for the case of monotonic loading, the elastoplastic behaviour is nearly isotropic in the plane of the plate, whereas under cyclic loading below the limit load, the equivalent solid material exhibits distortional hardening.

The helical spring lock washer (HSLW) is a part of nut bolt joint assembly used in different industries like automobile, aerospace, mechanical, chemical, electrical, electronics, etc. It works as a part of temporary joint and plays important role in loosening behavior of assembly under dynamic (vibrations) conditions. Thus, the purpose of this paper is to investigate the performance of HSLW under different controlled operating conditions in order to satisfy its functional requirement.

In the present investigation, a novel test rig is designed and developed to determine the load-deflection characteristics of HSLWs. The test rig facilitates the controlled linear displacement of the HSLW with predetermined angular rotation of the handle gives the corresponding reaction load on the display. Additionally, the repeatability and reproducibility of the test rig was carried out.

The newly designed and developed test rig is capable enough to differentiate the load-deflection characteristics during compressive loading and unloading of HSLWs. Additionally, the loss of strain energy can be determined from the load-deflection characteristics of HSLW.

The present test rig is designed and developed to investigate the load-deflection characteristics under compressive loading and unloading of HSLW. The test rig has least count of 0.4905 N for load measurement and 0.01389 mm for linear displacement.

The purpose of this paper is to contribute to the solution of the buckling and resonance stability problems in inelastic beams and wooden plane trusses, taking into account geometric and material defects.

Two sources of non-linearity are analyzed, namely the geometrical non-linearity due to geometrical imperfections and material non-linearity due to material defects. The load-bearing capacity is obtained by the rheological-dynamical analogy (RDA). The RDA inelastic theory is used in conjunction with the damage mechanics to analyze the softening behavior with the scalar damage variable for stiffness reduction. Based on the assumed damages in the wooden truss, the corresponding external masses are calculated in order to obtain the corresponding fundamental frequencies, which are compared with the measured ones.

RDA theory uses rheology and dynamics to determine the structures' response, those results in the post-buckling branch can then be compared by fracture mechanics. The RDA method uses the measured P and S wave velocities, as well as fundamental frequencies to find material properties at the limit point. The verification examples confirmed that the RDA theory is more suitable than other non-linear theories, as those proved to be overly complex in terms of their application to the real structures with geometrical and material defects.

The paper presents a novel method of solving the buckling and resonance stability problems in inelastic beams and wooden plane trusses with initial defects. The method is efficient as it provides explanations highlighting that an inelastic beam made of ductile material can break in any stage from brittle to extremely ductile, depending on the value of initial imperfections. The characterization of the internal friction and structural damping via the damping ratio is original and effective.