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1

Simulations and tests of composite marine structures under low-velocity impact

Zhu Zhaoyi, Li Xiaowen, Chen Qinglin, Cai Yingqiang, Xiong Yunfeng

Polish Maritime Research

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2021

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nr 1

59--71

EN

Due to their excellent performance, composite materials are increasingly used in the marine field. It is of great importance to study the low-velocity impact performance of composite laminates to ensure the operational safety of composite ship structures. Herein, low-velocity drop-weight impact tests were carried out on 12 types of GRP laminates with different layup forms. The impact-induced mechanical response characteristics of the GRP laminates were obtained. Based on the damage model and stiffness degradation criterion of the composite laminates, a low-velocity impact simulation model was proposed by writing a VUMAT subroutine and using the 3D Hashin failure criterion and the cohesive zone model. The fibre failure, matrix failure and interlaminar failure of the composite structures could be determined by this model. The predicted mechanical behaviours of the composite laminates with different layup forms were verified through comparisons with the impact test results, which revealed that the simulation model can well characterise the low-velocity impact process of the composite laminates. According to the damage morphologies of the impact and back sides, the influence of the different layup forms on the low-velocity impact damage of the GRP laminates was summarised. The layup form had great effects on the damage of the composite laminates. Especially, the outer 2‒3 layers play a major role in the damage of the impact and the back side. For the same impact energy, the damage areas are larger for the back side than for the impact side, and there is a corresponding layup form to minimise the damage area. Through analyses of the time response relationships of impact force, impactor displacement, rebound velocity and absorbed energy, a better layup form of GRP laminates was obtained. Among the 12 plates, the maximum impact force, absorbed energy and damage area of the plate P4 are the smallest, and it has better impact resistance than the others, and can be more in line with the requirements of composite ships. It is beneficial to study the low-velocity impact performance of composite ship structures.

2

Design and mechanical analysis of a composite T-type connection structure for marine structures

Li Xiaowen, Zhu Zhaoyi, Li Yan, Hu Zhe

Polish Maritime Research

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2020

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nr 2

145--157

EN

A new T-type connection structure consisting of composite sandwich plates, reinforced cores and adhesive was proposed for the construction of lightweight ships to resolve connection problems between bulkheads and decks of composite lightweight ship superstructures. Based on the design principles and mechanical properties of composite structures, the mechanical behaviour of the structure under a dangerous loading condition was investigated. In addition, the ultimate bearing capacities and damage modes were examined, the results of which demonstrated that the strength of the structure is weak, and that the adhesive and reinforced core between the face plate and the web plate is the primary weakness of the structure. A numerical simulation method was verified using the results of the mechanical tests, and five characteristic paths at the connection area were established. The stresses and displacements along the five paths were calculated using the numerical method. Then, variations in the geometric parameter and the strength and weight of the connection were summarised. The optimal angle of the adhesive bonding area is approximately 60°, which supports the optimal design and practical application of the lightweight ship adhesive-bonded connection structure.

3

Zbiór dopuszczalnych planów montażu wielkowymiarowych konstrukcji oceanotechnicznych

Iwańkowicz R.

Zarządzanie Przedsiębiorstwem

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2014

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Vol. 17, nr 2

17--25

EN

The aim of the article is presenting a mathematical model of the assembly process of large-size marine structures. Numerical encoding approach of essential features of the structure and welding methods is proposed. The model takes into account information about the geometry of the connections between elements and their orientation in space during the assembly process. Welding processes are characterized by positions range of their application. The assembly process is shown as a matrix form. Assembly planning is based on the allocation of welding processes into stages and the selection of welding method and assembly position for each stage. It is shown that a lot of such plans can be generated and many of them are unacceptable. Space of feasible plans is defined by set of constraints. These conditions verify that the assembly plan performs a task of welding of all joints and whether it is feasible for particular methods. The methods for calculating the impact of all conditions . an accurate deterministic and randomized approximate are proposed. It is shown that assumed conditions dramatically reduce the set of assembly plans. Moreover, the method of including additional conditions into the model according to the connections making sequence is presented. Sample calculations are shown in two examples . first that is extremely simplified, allowing for a full deterministic analysis of the problem, and a second that is more complex, requiring a partial approximate approach. The article indicates the possibility of using the optimization of the assembly plan. Furthermore, the set of applicable criteria is proposed.

4

Korozja i metody zabezpieczeń antykorozyjnych w konstrukcjach okrętowych

Szymczak M.

Przegląd Spawalnictwa

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2012

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R. 84, nr 12

44-51

PL

Korozja jako zjawisko powoduje za sobą olbrzymie straty i generuje dużo problemów dla technologów, konstruktorów i spawalników. Zjawisko to jest trudne do zminimalizowania – wręcz niemożliwe do uniknięcia. Opracowano dużo metod zabezpieczeń konstrukcji przez korozją, a wybór właściwej musi być oparty na odpowiedniej wiedzy nt. warunków pracy i wymagań stawianych konstrukcji. W artykule przedstawiono rodzaje korozji konstrukcji okrętowych, główne miejsca jej występowania, wymagania stawiane zabezpieczeniom antykorozyjnym, przygotowanie konstrukcji do malowania i podstawowe metody zabezpieczeń antykorozyjnych.

EN

Corrosion as a phenomenon entails a huge loss for humanity and generates a lot of problems for engineers, designers and welding community. This phenomenon is difficult to reduce – even impossible to avoid. Developed a lot of methods of construction corrosion protection and the selection of the appropriate must be based on adequate knowledge about the structure working conditions and requirements for it. This paper presents the types of corrosion of ship structures, the main place of its occurrence, corrosion protection requirements, preparation for the structure painting and basic methods of corrosion protection.

5

Spawanie wielkogabarytowych elementów wsporników (typ V) wałów śrubowych statków

Urbański M.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2011

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R. 55, nr 2

55-56

PL

Przedstawiono praktyczne aspekty uruchomienia i wykonania spawania staliwnej, wielkogabarytowej konstrukcji okrętowych wsporników wałów śrubowych. Omówiono zagadnienie kwalifikacji procedur spawania, prowadzenia prac montażowo - spawalniczych w połączeniu z ich monitoringiem i miejscowej obróbki cieplnej złączy oraz niektóre aspekty kontroli nieniszczącej spoin. Całość prac nadzorowana była przez Towarzystwo Klasyfikacyjne Lloyd`s Register of Shipping.

EN

It has been presented practical aspects of qualification of welding procedure for large-size structure of the brackets of screw shafts made of cast steel and performing of real welding operation. The issue of qualification of welding procedures, conducting of assembly-welding works coupled with their monitoring and local heat treatment of welded joints as well as some aspects of non-destructive testing of welds have been discussed. The whole work was supervised by the Lloyd's Register of Shipping.

6

Wpływ rodzaju zbrojenia i kolejności ułożenia warstw na tolerancję zniszczeń wywołanych udarami o małej prędkości laminatów epoksydowych zbrojonych włóknem węglowym, szklanym, kevlarowym i hybrydowych

Imielińska K., Wojtyra R.

Kompozyty

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2002

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R. 2, nr 5

364-368

PL

W pracy, będącej fragmentem projektu dotyczącego wprowadzania nowych materiałów kompozytowych do budowy małych jednostek pływających, porównano zachowanie pod obciążeniem statycznym i udarowym laminatów epoksydowych zbrojonych tkaniną węglową lub szklaną z własnościami laminatów hybrydowych zawierających zarówno zbrojenie szklane, jak i węglowe w różnej ilości i układzie geometrycznym. Określono odporność udarową za pomocą kryterium poudarowej wytrzymałości na ściskanie związanej z wielkością pola zniszczeń w laminacie poddanym uderzeniu o określonej energii. Kryterium to można też określić mianem tolerancji zniszczeń spowodowanych przez udary o małej prędkości.

EN

Interest in composite materials for structural components has increased rapidly in the last decade. Proper selection of fibre and matrix may be expected to provide weight savings up to 50 percent over structural metals as well as improvements in fatigue endurance and corrosion resistance, reduced manufacturing costs and precise tailoring of material properties to service loads. In spite of these and other advantages which can be achieved with composite materials their use in many applications has been limited by concerns over their susceptibility to impact damage during the manufacturing process and in service as well as the corresponding reductions in mechanical properties resulting from such damage [1-3]. Consequently damage resistance and damage tolerance under impact loading can be regarded as most important characteristics of fibre reinforced composites [4]. Depending on the characteristics of composite constituents the choice of fibre and matrix type, laminate configuration and loading geometry the damage process can be a very complex combination of energy absorption mechanisms. In particular the selection of the types of fibres, form of reinforcement (woven or unidirectional) as well as stacking sequence play an important role in determining failure mechanisms, the extent of damage and the threshold energy of the composite. Often this damage may not be visible from the laminate surface, but its presence substantially reduces the mechanical properties of the composite, especially the in-plane stiffness and strength [7j. The results presented in this paper are a part of a broader study of new laminates for marine structures. The purpose of the project was to characterise the impact response and impact damage tolerance of four different laminates considered for use in construction of small ships. Woven carbon fabric and glass fabric laminates have been compared with the behaviour of laminates with different stacking sequence of carbon and glass layers (E/C/E/C/E/C/E, C/E/C/C/E/C, C/C/E/E/E/E/C/C) as well as Kevlar-glass and Kevlar-carbon fabric laminates. Impact behaviour was assessed on (100x100 ram) square laminate specimens using a dropweight facility. Weights with a hemispherical nose of 12 mm in diameter were dropped through 1 m along the rails to hit the laminate at the centre of the span of the specimen freely supported on the steel plate with a central, circular opening 38 mm in diameter. The weights were adjusted to give the incident energies 10:64J. Three specimens have been tested for each impact energy level. The impact resistance was assesed in terms of internal delamination surface area resulting from impact of a given incident energy. The extent of impact damage has been estimated by ultrasonic C-scan technique or by visual inspection. The first method has been applied to the specimens containing carbon fibres which were opaque to light. The second approach was used in the case of glass and Kevlar-glass laminates for which visual observation of internal damage against the strong source of light was possible. Compression after impact tests were performed on impacted square specimens (100x100 mm) using abtibuckling device. The graphs of impact damage area vs. normalised impact energy have been plotted and compression strength after impact has been related to the area of impact damage. For comparison, the same plots have been analysed for Kevlar-carbon fabric and Kevlar-glass fabric laminates. Tensile and bending strengths have also been compared for different laminates. It has been concluded that all carbon-glass laminates had similar post-impact compression strength for the same area of impact damage regardless the stacking sequence. Kevlar-glass fabric laminate showed similar damage tolerance and mechanical properties as carbon-glass laminates. Despite the high price laminates reinforced with Kevlar-carbon fabric were importantly inferiour than other materials. Regarding low velocity impact damage tolerance, in the case when the extreme strength and stiffness are not required, expensive carbon laminates tested in the present work can potentially be replaced by cheaper carbon glass-epoxy laminates of diverse stacking sequence as well as by Kevlar-glass fabric laminates.

7

Impact resistance and damage tolerance of hybrid: carbon, glass, Kevlar/epoxy laminates.

Imielińska K., Wojtyra R., Castaings M.

Inżynieria Materiałowa

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2001

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R. XXII, nr 4

388-391

EN

As a part of a broader study of new laminates for marine structures a drop weight impact response and residual compression strength after impact of four laminates reinforced with carbon, carbon and glass, Kevlar/carbon and Kevlar/glass fabrics have been studied. Impact damage surface area corresponding to the impact energy level has been estimated by means of air-coupled ultrasonic C-scan technique. Minor differences in performance of laminates in which carbon fibres have been partly replaced by glass fibres may indicate that carbon fibre laminates can be replaced by cheaper carbon/glass or Kevlar glass laminates.

PL

W ramach szerszego programu badań zastosowania nowych materiałów na konstrukcje okrętowe zbadano odporność na uderzenia spadającym ciężarem i poudarową wytrzymałość na ściskanie czterech laminatów wzmocnionych włóknem: węglowym, węglowym i szklanym, Kevlarowym/węglowym, Kevlarowym/szklanym w postaci tkanin. Rozmiar strefy zniszczeń odpowiadających danemu poziomowi energii uderzenia, przyjęty jako kryterium odporności udarowej został wyznaczony metodą ultradźwiękową ze sprzężeniem powietrznym. Niewielkie różnice w zachowaniu materiałów uzyskane dla laminatów, w których włókna węglowe zastąpiono częściowo szklanymi wskazują na możliwość zastępowania laminatów wzmocnionych włóknami węglowymi tańszymi laminatami węglowo-szklanymi lub Kevlarowo/szklanymi.