Structure Life Extension towards the Structural Integrity of Sukhoi Su-30MKM

The airframe structures of most fighter aircraft in the Royal Malaysian Airforce have been in service for 10 to 20 years. The effect of fatigue loading, operating conditions, and environmental degradation has led to the structural integrity of the airframe being assessed for its airworthiness. Various NDT methods were used to determine the current condition of the aircraft structure after operation of beyond 10 years, and their outcomes are summarized. In addition, although there are six critical locations, the wing root was chosen since it has the highest possibility of fatigue failure. It was further analyzed using simulation analysis for fatigue life. This contributes to the development of the maintenance task card and ultimately assists in extending the service life of the fighter aircraft. Using the concept of either safe life or damage tolerance as its fatigue design philosophy, the RMAF has adopted the Aircraft Structural Integrity Program (ASIP) to monitor the structural integrity of its fighter aircraft. With the current budget constraints and structural life extension requirements, the RMAF has embarked on the non-destructive testing method and engineering analysis. The research outcome will enhance the ASIP for other aircraft platforms in the RMAF fleet for its structure life assessment or service life extension program.

A Real Time Fatigue Monitoring Platform for Flexible Risers

Fatigue life of flexible risers is a critical design factor in offshore riser system design. To estimate the fatigue damage, global and local analyses are performed inhouse with inputs from operators. Metocean data, riser properties, vessel or platform RAO data are typical inputs for the fatigue analysis. In addition to the conservatism inherited in the product design methodology and API safety factor 10 for fatigue estimation, the input data may also contain some additional conservatism compared to actual operational conditions as these were estimated/projected from limited time-span of observations or predicted purely from numerical modelling. In combination, these inheriated conservatism permits the feasibility of service life extension of the flexible riser systems. Many platforms or vessels already have real time monitoring of motions in multiple degrees of freedom and wave/current data. Furthermore, pipe internal operating conditions like pressure and temperature are usually recorded onboard. Compared to the typical input data/assumptions made in predictive analysis, these records are more precisely and directly related to the actual fatigue damage accumulation. With real time data, a more accurate estimation on fatigue performance of riser can be achieved, which could enable the service life extension without compromising the design safety factors. A special software tool has been developed to calculate the real time fatigue damage of flexible tensile wires. The software is based on product design tools which are calibrated and independently validated with over 30 years installed operational experience. Developed in Python, the software utilizes an OrcaFlex API and a local analysis algorithm in the background. The software can be customized towards different platforms and pipe systems, as well as input data types. Depending on clients’ needs, multiple fatigue hot spots like top end fitting, bend stiffener region or touch down zone can be monitored at the same time. Other parameters like riser real time extreme response or statistical results can also be checked in the software. This paper summarizes the development of the pipe monitoring system. It is believed that with real time inputs, the software can better assist clients to monitor the pipe fatigue performance and other related riser responses.

Investigation on the Running-In Quality at Different Rotating Speeds by Chaos Theory

Improving running-in quality is an important project of Green Tribology. In actual environment, the running-in quality of mechanical equipment is greatly affected by system parameters. In view of this, running-in experiments were performed at different rotating speeds on a pin-on-disc tribometer. Chaos theory was used to investigate the effect of rotating speeds on the running-in quality. The experimental results showed that the running-in quality could be better evaluated by using the chaotic characteristic parameter “Convergence (CON)”. The greater the CON, the better the running-in quality. With an increase of the rotating speed, CON first gradually increased and then decreased to a certain level, whilst the running-in quality first gradually became better and then became worse. A moderate rotating speed is advantageous to obtain the optimum running-in quality. This contributes to the service life extension and the efficiency improvement, so as to reduce energy consumption.

Effect of rust inhibitors and surface strengthening materials on service life of marine RC structures

Purpose The purpose of this paper is to compare the effect of rust inhibitors and surface strengthening materials on the service life of RC structures in tropical marine environments and ultimately to provide basis and recommendations for the durability design of reinforced concrete (RC) structures. Design/methodology/approach Slag concrete specimens mixed with four kinds of rust inhibitors and coated with four kinds of surface strengthening materials were corroded by seawater exposure for 365 days, and the key parameters of chloride ion diffusion were obtained by testing. Then a new service life prediction model, based on the modified model for chloride ion diffusion and reliability theory, was applied to analyze the effect of rust inhibitors and surface strengthening materials on the service life of RC structures in tropical marine environments. Findings Rust inhibitors and surface strengthening materials can effectively extend the service life of RC structures through different effects on chloride ion diffusion behavior. The effects of rust inhibitors and surface strengthening materials on the service life extension of RC structures adhered to the following trend: silane material > cement-based permeable crystalline waterproof material > hydrophobic plug compound > spray polyurea elastomer > water-based permeable crystalline waterproof material > calcium nitrite > preservative > amino-alcohol composite. Originality/value Using a new method for predicting the service life of RC structures, the attenuation law of the service life of RC structures under the action of rust inhibitors and surface strengthening materials in tropical marine environments is obtained.

Effectiveness of the Novel Rehabilitation Method of Seismically Damaged RC Joints Using C-FRP Ropes and Comparison with Widely Applied Method Using C-FRP Sheets—Experimental Investigation

The necessity of ensuring the long-term sustainability of existing structures is rising. An important issue concerning existing reinforced concrete (RC) structures in seismically active regions is that a significant number of them lack the required earthquake-resistant capacities to meet the increased design earthquake demands. Inexpensive, fast and long-term strengthening strategies for repairing/strengthening RC structures are urgently required, not only after destructive earthquakes, but even before they occur. Retrofitting existing buildings extending their service life rather than demolishing and rebuilding new ones is the best option in terms of economic gain and environmental protection. This paper experimentally investigates the effectiveness of externally applied (i) carbon fiber-reinforced polymer (C-FRP) ropes in X-type form and (b) C-FRP sheets that are bonded on both sides of the joint area of RC beam-column joint connections. Six comparative full-scale exterior RC beam-column joint specimens were tested under reverse cyclic deformation. Two of them were control specimens, two were strengthened using C-FRP ropes (novel technique) and two were retrofitted using C-FRP sheets (widely used technique). Extensive comparisons and discussion of the test results derive new quantitative and qualitative results concerning the seismic capacity and the service life extension of the strengthened RC members using the proposed retrofitting scheme.

Strength assessment of the body of a weight checking wagon type 640-VPV

In the article, necessary to design and build new and modern weighing wagons to replace the outdated ones, but this will take some time. Thus, before the construction of new wagons and the optimal use of existing wagons, it is necessary to extend their service life. Extension of the service life of weighing wagons involves determining the current technical condition and residual resources of these wagons. For this purpose, a survey and analysis of the main bearing elements and structural parameters of the bodies of the weighing wagons were carried out.