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Determination of additional tension in towed streamer cable triggered by collision with underwater moving object

100%

Blintsov V. S. , Trunin K. S. , Tarełko W.

tom nr 2

58--68

The paper deals with issues connected with the behaviour of a streamer cable towed by a survey seismic vessel when the cable undergoes a strike triggered by collision with an underwater moving object. The consequences of such collisions may be both threat to the life of marine animals or damage to underwater units and large economic losses suffered by vessel owners. The risk of such collisions has increased over the last years as a result of increased offshore seismic survey operations. Therefore, a towed streamer should be very robust. To assure its robustness, we should know the deformation mechanism of a single streamer cable. This in turn requires the development of an appropriate mathematical model of such a phenomenon. In particular, the paper presents the characteristics of seismic survey vessels and streamers; an analysis of collisions that have occurred in the past; a statement of the problem, and a computer-aided system supporting simulation of the cable behaviour. To obtain all the necessary design parameters regarding the deformation mechanism of a streamer cable, we set up a dedicated computer-aided system that supports their calculation.

Investigating the capability of the Lemaitre damage model to establish the incremental sheet forming process

63%

Kumar P. , Tandon P.

2022

tom Vol. 22, no. 2

art. no. e66, 1--18

This paper presents the numerical and experimental investigation of the incremental sheet forming (ISF) process with the Lemaitre damage model to incrementally form parts of conical shapes. The Lemaitre damage model was prepared as a material subroutine (VUMAT) and linked to Abaqus/Explicit. The elastic–plastic parameters for the simulation were identified through tensile testing of the ASTM E8 specimen. The digital image correlation (DIC) was performed during the tensile testing to identify the damage parameters of the Lemaitre damage model. Scanning electron microscopy (SEM)-based area method was used to identify the area fraction vis-a-vis the variation of the strain. Thereafter, the identified area fractions with respect to strains have been calibrated to obtain the damage parameters through an inverse analysis approach. The identified parameters were used to form conical objects of Al1050 H14 sheets of 2 mm thickness through finite element (FE) simulation. The results obtained through FE simulation were compared with the experimental outcomes to investigate the efficiency of the Lemaitre damage model to simulate the ISF process. The responses obtained through FE simulation and experiments have been discussed in terms of limiting wall angle and forming depth, damage evolution, deformation mechanism, forming limit diagram, geometrical accuracy, forming forces, thickness distribution, and surface roughness.

Deformacionnyj mehanizm uplotneniăstrukurnogo tela

63%

Protasenya O. N. , Larchenkov L. V. , Protasenya M. L. , Jakubowski A.

tom nr 1

46--52

Application of agricultural technique for preparation (loosening) of soil to sowing of agricultural cultures has an ambivalent character: from one side, elimination of weeds, and from the other mechanical destruction by the eyelids of the folded structure of soil profiles. The questions of compression of structure of soil are considered in the process of her forming and influence of the external loading without substantial violation of the structure.

Wpływ pasm ścinania na teksturę i własności mechaniczne walcowanej miedzi

51%

Stalony-Dobrzański F. , Bochniak W.

tom R. 51, nr 1

11-25

Wykazano związek pomiędzy zjawiskami strukturalnymi a teksturą i własnościami mechanicznymi miedzi poddanej jednokierunkowemu i krzyżowemu walcowaniu oraz próbie rozciągania. W szczególności, ujawniono dominującą rolę mechanizmu zlokalizowanego plastycznego płynięcia w pasmach ścinania po zmianie drogi odkształcenia wywołanej rozciąganiem próbek w kierunku prostopadłym do kierunku walcowania. Znalazło ono również odzwierciedlenie w obrazach tekstury odkształcanej miedzi oraz dwukrotnie wyższej wartości współczynnika Lankforda w porównaniu z wartością określoną z próbek poddanych rozciąganiu w kierunku zgodnym z kierunkiem walcowania.

Relationship between structural phenomena, texture and mechanical properties of copper subjected to non-reversing rolling, alternate longitudinal and cross rolling and to a tensile test, has been proved. In particular, the dominant role of a mechanism of localized plastic flow in the shear bands after the change of a strain path caused by tension applied perpendicularly to the rolling direction has been revealed. This phenomenon has also been reflected in the images of a texture of copper under deformation and in twice higher value of a Lankford’s coefficient compared to that determined for the samples subjected to the tensile test in the direction consistent with the rolling direction.