Load-carrying Structure Research Articles

Integration of Piezoceramic Tube under Prestress into a Load Carrying Structure

Smart structures consisting of a load carrying structure and smart materials with actuatory and sensory capabilities feature high potential in numerous applications. However, to master the assembly conditions of smart structures, there is a need to integrate additional design parameters such as prestress of the smart material, critical loads and electric contacting as well as insulation into the process development. This paper focusses on the design of an incremental bulk forming process to integrate piezoceramic components into an aluminum tube simultaneously to the manufacturing process. Axial forces imposed on the piezoceramic are investigated numerically and experimentally to verify the design of critical components and the process control. Within this investigation, in situ measurement of the direct piezoelectric effect provides a method to validate the numerical design with regard to failure of the piezo tube and the functional properties of the overall structure.

Effect of heating on the load-carrying structure mass

The effect of heating on the mass of load-carrying structures is analyzed using the weight Komarov formula in the framework of the design calculations by examples of a panel and spar. The results obtained have been compared with the data on real structures of supersonic passenger aircraft and aerospace aircraft of reusable transport systems.

Reducing drilling-induced delamination in composite tube by magnetic colloid back-up

Drilling is an indispensible machining process for building a load-carrying structure of composite materials. Delamination defect is often produced at the exit of drilling, which threatens the service safety of the structure. There are back-up methods to reduce delamination when drilling the open flat-plate composite structure, but none for drilling into the curved-surface or hollow-shape structures. This study describes an innovative method using electromagnet and the deformable inexpensive colloid mixed with iron powder to produce magnetic back-up force at drilling exit to suppress delamination in industrial tube parts. The delamination extent can be reduced by 60–80%. The optimal volume ratio of powder-to-colloid is found 1:3.

Classification of Structural Steel of Existing Civil Engineering Structure Based on Testing and Evaluation of Yield and Ultimate Strengths

The paper is generally focused on yield and ultimate strengths of structural steels. The attention is mainly paid to the testing and subsequent determination of steel strengths, especially from the viewpoint of the statistical evaluation aimed to obtain the strength values leading to the reliable structural design, in the meaning of general rules given by the European Standard for the structural design of civil engineering constructions. The presented paper deals with the actual yield and ultimate strengths obtained from material tests and their characteristic and design values based on the test results evaluation, versus nominal and design values considered according to European Standard rules and used for the structural design in the usual cases if the steel grade is known. But in the case of existing constructions, sometimes there are no information about the material that the actual steel properties shall be determined using the material tests and their statistical evaluation to obtain such steel properties values which can lead to the reliable structural design. However, approaches of the determination of characteristic and design steel strengths using actual test results are different from the determination of the nominal and design steel strengths given by standard rules. As an illustration the paper summaries the results and evaluations of tests of structural steel performed on the specimens taken from the load-carrying roof structure of the sport stadium aged about 40 years, within the steel construction diagnostics.

Application of SPF/DB New Structure to Titanium Main-Load Carrying Components

In this paper, we proposed a new superplastic forming and diffusion bonding (SPF/DB) structure and processed validation between traditional SPF/DB four sheets structure and the new structure at the coincidence boundary conditions by FEM method. The calculation results show that the new structure can decreases the maximum stress at the joining part by 82% and decreases the maximum displacement at the aerofoil tip by 51% at the cost of the mass increases less than 20%. It induces that the new structure presents better stiffness and greater load carrying capacity than traditional ones, therefore, it could be used in titanium main load-carrying structure especially the structure which has the assembling and lose weight requirement very effectively.

On Problems of Mechanical Properties of Structural Steel in Load-Carrying Structure of Historical Building Construction

The paper is focused on the problems of the mechanical properties of steel used for load-carrying structures of civil engineering constructions, especially from the viewpoint of properties of old steels used in historical constructions in comparison with current steels. Chemical composition and physical-mechanical properties of historical steels can be important, for example, in the case of reconstructions, when for the static assessment and evaluation of existing constructions subjected to new (higher) loading actions, material properties of load-carrying structure must be known. In the case of constructions aged about 100 years, usually no project documentation and no information about used material and its properties exist. Then, the properties must be determined using material tests carried-out on the test specimens taken from the real existing structure. But here the sampling of test specimens is limited by the possibilities of existing structural system and by the dimension of particular members from which the specimens are taken, so that the test specimen dimensions and number are limited. Thus, the evaluation of material properties for obtaining representative design values can be more difficult and less reliable than in the case of the large test number. But the main problem is to determine the usable design values of material properties (design yield and ultimate strength) to utilize them for the reliable static re-design of existing structure under actual loading actions. Some problems indicated above have been shown on the example of the material analysis of steel load-carrying structure of slaughterhouse aged more than 100 years. This analysis has been performed recently within the framework of the construction exploration in connection with the intended revitalization of historical “industrial zone” in the city of Brno, Czech Republic.

DECREASING DISPLACEMENTS OF PRESTRESSED SUSPENSION BRIDGE

A suspension bridge is the most suitable type for a long-span bridge due to rational use of structural materials. Increased deformability, which is conditioned by the appearance of the elastic and kinematic displacements, is the major disadvantage of suspension bridges. The problem of increased kinematic displacements under the action of symmetrical and non-symmetrical load can be solved by the prestressing. A prestressed suspension bridge with span of 200 m was considered as an object of investigations. The cable truss with the cross web was considered as the main load carrying structure of prestressed suspension bridges and was compared with the single cable. The considered prestressed suspension bridge was investigated by the FEM program ANSYS 12 and by the small scale physical model. Rational, from the point of view of minimal vertical kinematic displacements, main load-carrying structure of prestressed suspension bridge was developed. The obtained results shows, that usage of cable truss with the cross web as the main load carrying structures of prestressed suspension bridge in comparison with the single cable, reduces vertical displacements upwards by 63.1%, downwards by 1.8% and total displacements by 29.6% under the action of worth situated load.

Optimisation of Sandwich Panels for the Load Carrying Structure of High-Speed Rail Vehicles

International Journal of Aerospace and Lightweight Structures (IJALS) | The journal aims to promote international exchange of new knowledge and recent development in aspects of aerospace, vehicle, ship and ocean engineering. Topics of interest include strength and vibration of structures, mechanical behavior of materials, dynamics and vibration control, fluid-structure interaction, etc.. The journal solicits contributions from scientists, engineers and others who are directly or indirectly involved in the promotion of aerospace and lightweight structures in the form of full length paper or technical note. It explores analytical, computational and experimental progresses in all the above mentioned areas.

Delamination reduction in drilling composite materials by active backup force

Composites have been widely employed in various industries due to their outstanding mechanical properties and corrosion resistance. Drilling is an indispensible operation for building a load-carrying structure. Delamination, however, is among the serious concerns in drilling composite-based components in practice. This paper describes a novel method for the reduction of delamination during drilling of composites by active backup force. The applied backup force contributes to suppression of the growth of the delamination at drilling exit by 60–80%. The proposed novel drilling technique reveals the potential for fabrication of composite components at low cost and minor delamination with high feed rate.

Experimental Study on the Influence of Water Jetting upon the Load-Carrying Ability of Hot Clay Brick

The paper reviewed briefly the current situation of using the buildings which have solid brick wall as the main load-carrying structure in china. The experiment is carried out to study and analyze the consequence of the brick construction which resisted pressure under fire-water sprinkling and high temperature. Compared with the different conditions, the experimental test shows that the structure and the resistibility of the clay brick changes dramatically with constant fire-water sprinkling and increased temperature, that provides some primary data to relative fields.

Application of the acoustic-emission and strain-gaging methods to testing of the residual strength of airplanes

The use of acoustic-emission (AE), optical, and strain-gaging methods in cyclic tests of an airplane has been considered. During tests, before the failure of an airplane, three zones were inspected. For this purpose, saw cuts were made in the lower planes of the left and right wings and in the load-carrying structure on the right side. The AE method allowed detection of growing flaws at a 10% load relative to the rated load, when the length of a fatigue crack was at most 1 mm and was not detected via the optical method.

Superelement-Based Modeling of Load Distribution in Large-Size Slewing Bearings

The supporting structures in large-size slewing bearings are highly flexible. In order to choose the proper bearing and shape the load-carrying structure one must estimate the distribution of forces among the individual rolling elements. Advanced numerical models are needed for this. An original method of modeling the rolling element-track system is presented and its usefulness for modeling large-size bearings is demonstrated. The results of an exemplary analysis are presented in the form of graphs and figures. The superelement-based discrete bearing models are so far most comprehensive and take into account all the phenomena involved in the bearing-supporting structures system. The application of the finite-element method and the models based on the track-rolling element-track superelement made it possible to determine the effect of the deformability of the supporting structures and the nonuniformity of their flexibility on the loading of the rolling elements in the two-row bearing. The use of formulas which do not take into account the flexibility of the supporting structures to determine the distribution of the load among the rolling elements is unacceptable.

Tests During Three Stages of Construction of a Road Bridge with a Flexible Load-Carrying Structure Made of Super Cor Type Steel Corrugated Plates Interacting with Soil

The way in which a new road bridge made of steel corrugated plates Super Cor type was tested during the three stages of its construction is described and the test results are presented. Backfill in construction Stage I and two ballasting vehicles in Stages II and III constituted the loads. The box bridge spans the Bystrzyca Dusznicka River in Polanica Zdroj, Poland. The span’s effective length is 12.27 m and its vertical inside diameter is 3.85 m . The steel span is founded on two reinforced concrete strip foundations. The average values of the displacements and strains (normal stresses) measured in selected points and on selected elements of the steel shell structure were much smaller than the ones computed for the same load. The conclusions drawn from this research can be helpful in determining the interaction between the steel shell and the backfill. Since this type of steel–soil structure is increasingly used in Poland and in the world, the conclusions can be generalized to a whole class of similar br...

Principles of material selection, evaluation of performance, desing and technology of industrial production of the load-carrying structure of “ITER” superconducting magnetic system

The paper gives analysis of existing materials for fabrication of superconducting magnetic systems. Estimation of weldability, performance of welded structures, adaptability of up to 450 mm thick plates for industrial manufacture is given. It is recommended for the “ITER” Project to use weldable steel 03X20H16AP6. The steel having thickness 450 mm possesses the following properties at 1.2 K: UTS = 1650 MPa; YS = 1200 MPa, K 1c = 250 MPa√m. The wide international cooperation is required for solving the problems arising in creation of SMS “ITEr”.

Use of PT and PTG textolites in sulfuric acid electrofilters

This article examines structural laminar plastics in ShMK electrofilters to determine the possibilities of using these materials for producing load-carrying structures of the precipitation system with plastic electrodes. The research was conducted on chemically, thermally, and moisture-resistant difficult-to-combust commercial textolites PT and PTG (graphitized) in the form of sheets with a thickness of respectively 10 and 4.5 mm. Industrial tests on textolites were conducted in an ShMK-9.6 electrofilter installed in the first stage of gas scrubbing in the flashing section of the sulfuric acid contact shop for 3900 h. The chemical stability of the materials was evaluated on the basis of the changes of the weight, linear dimensions, and external appearance of the specimens (screening tests), and on the basis of the variation of the weight and short-term strength in tensile testing. It is established that the textolites PT and PTG with a thickness of 10 mm can be used in the load-carrying structure consisting of two strips with electrode plates fixed between them. The use of 400 kg of textolite for producing suspension beams for sulfuric acid plate electrofilters with electrodes made of plastics made it possible to save 715 kg of lead and 610 kg of carbon steel.

11—A THEORETICAL MODEL FOR PREDICTING THE STRENGTH OF SINGLES WORSTED YARNS

A theoretical model is presented that depicts the major factors contributing to the mean strength of singles worsted yarns. Based upon essential concepts introduced by Sullivan in 1942, the formulae include extensions that have been found necessary to give an accurate representation of the strength of such yarns. The most important new concept is that of an ‘ineffective’ outer layer of fibres that does not contribute directly to the strength of the yarn, though it could play a part in initiating the development of lateral pressures within the structure. It is this latter process which, in conjunction with inter-fibre frictional forces, permits a yarn made of staple fibres to function as an effective load-carrying structure.

Structural Weight Estimations for Novel Configurations

SummaryThe aims of structure weight estimation are discussed and a review is given of its development in this country during the past fifty years from the simplest of formulae to quite detailed methods. The limitations of formulae derived only from statistical analysis of actual aircraft structures are noted. For aircraft of novel configuration it is essential for the weight of the basic load-carrying structure to be estimated by methods which are based upon the actual design and stressing procedures. The principles of “optimum” or “minimum-weight” structural design are a valuable feature of such methods and are briefly described. Statistical analysis, however, is still important for estimating the substantial weight of the joints, cutouts, transparencies and other features which transform a theoretical optimum structure into a complete and practical one. The problems of several aeroplane and missile configurations of current interest are discussed, and also the extent to which detailed design work is necessary to provide reliable structure weight estimates for such projects.