scholarly journals Effect of Mechanical Properties of Fasteners on Stress State and Fatigue Behaviour of Aircraft Structures as Determined by Damage Tolerance Analyses

2015 ◽  
Vol 101 ◽  
pp. 135-142 ◽  
Author(s):  
Radek Doubrava
2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.


2012 ◽  
Vol 568 ◽  
pp. 39-42
Author(s):  
Yu Zhuo Jia ◽  
Li Lin

SAP2000 structural analysis software is used to designed two of 500kV partially prestressed reactive powder concrete pole cross arm; moreover, poles of the two cross arm program have been compared. The results show that the triangular truss cross arm has good mechanical properties, improving the main mate’rial of the stress state, the pole reduced height 10m, by the analysis of the structure shows, this cross arm has higher reliability under the operating conditions, which can be used in 500kV transmission line; from economic and technical performance, the pole cost of this program is greatly reduced, while speeding up the construction progress and improving the comprehensive benefits of the poles in the transmission line.


2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.


Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6085
Author(s):  
Victor I. Bolobov ◽  
Il’nur U. Latipov ◽  
Gregory G. Popov ◽  
George V. Buslaev ◽  
Yana V. Martynenko

Consideration of the possibility of transporting compressed hydrogen through existing gas pipelines leads to the need to study the regularities of the effect of hydrogen on the mechanical properties of steels in relation to the conditions of their operation in pipelines (operating pressure range, stress state of the pipe metal, etc.). This article provides an overview of the types of influence of hydrogen on the mechanical properties of steels, including those used for the manufacture of pipelines. The effect of elastic and plastic deformations on the intensity of hydrogen saturation of steels and changes in their strength and plastic deformations is analyzed. An assessment of the potential losses of transported hydrogen through the pipeline wall as a result of diffusion has been made. The main issues that need to be solved for the development of a scientifically grounded conclusion on the possibility of using existing gas pipelines for the transportation of compressed hydrogen are outlined.


2016 ◽  
Vol 258 ◽  
pp. 501-505
Author(s):  
Alice Chlupová ◽  
Milan Heczko ◽  
Karel Obrtlík ◽  
Přemysl Beran ◽  
Tomáš Kruml

Two γ-based TiAl alloys with 7 at.% of Nb, alloyed with 2 at.% Mo and 0.5 at.% C, were studied. A heat treatment leading to very fine lamellar microstructure was applied on both alloys. Microstructure after the heat treatment was described and mechanical properties including fatigue behaviour were measured. The as-received material alloyed with C possesses high strength and very limited ductility, especially at RT. After application of selected heat treatment it becomes even more brittle; therefore, this process could be considered as not appropriate for this alloy. On the contrary, in the case of Mo alloyed material, both strength and ductility are improved by the heat treatment at RT and usual working temperature (~750 °C). Presence of the β phase is responsible for this effect. The selected heat treatment thus can be an alternative for this alloy to other thermomechanical treatments as high temperature forging.


Author(s):  
I. Altenberger ◽  
Yuji Sano ◽  
M.A. Cherif ◽  
Ivan Nikitin ◽  
Berthold Scholtes

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