Temat: fracture analysis - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Influence of crack presence on operating conditions of pressure vessels with flat endplates
Autorzy:: Szybiński, B.
Romanowicz, P.
Tematy:: pressure boilers
flat ends
cracks
fracture analysis
FEM; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/242804.pdf Link otwiera się w nowym oknie
Opis:: The paper discusses influence of crack presence on operating conditions of boilers and pipes. In the study particular attention is paid to the vessels with flat endplates with circular stress relieve grooves. The endplates with such grooves are common alternative for widely used dished ends, particularly for smaller boiler diameters and also for vessels with non-circular cross-sections. The existing codes set the rules how to calculate the circular groove parameters – the groove radius and the location of the arc centre. These design parameters are limited by set of inequalities, which indicate the ranges for admissible radii values and the groove centre positions. The choice of the optimal values for the endplate design parameters has been worked out in recent Authors’ investigations. Such approach provides the minimum stress concentration in the vicinity of the cutout, but this notch area still can be the source of crack nucleation and its propagation leading to the premature fracture of the considered vessel. In standard calculations of pressure boilers, the fracture parameters are not taken into account. The current study concentrates on the assessment of the influence of the crack existence on the stable vessel operation. The cracks existing in inner wall of the vessel are of the main interest, because these are difficult to identify and monitor. In these studies the influence of different parameters like the crack length and orientation, and the fracture toughness were taken into account. The detailed numerical results were obtained by means of the finite element code ANSYS [1] for several crack sizes and locations. The cracks in the weld joining shell and end plate and cracks in the groove area, where the maximum stress concentration appeared were subject of the numerical study. The obtained results show the risk of possible premature failure of boilers with cracks.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The Morphology of Impact Fracture Surfaces in Manganese Cast Steel Modified by Rare Earth Elements
Autorzy:: Kasińska, J.
Tematy:: cast steel
modification
REM
impact strength
fracture analysis
staliwa
modyfikacja
siła uderzenia
pęknięcia; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/946876.pdf Link otwiera się w nowym oknie
Opis:: The morphology of G20Mn5 specimens made of non-modified and rare earth metals (REM) modified cast steel was investigated. Molten metal was treated with a cerium-rich mischmetal contain 49.8% Ce, 21.8% La, 17.1% Nd, 5.5% Pr and 5.35% other rare earth metals making up the balance. The melting, quenching (920°C/water) and tempering (720°C/air) were performed under industrial conditions. Analysis included G20Mn5 cast steel fracture specimens subjected to Charpy V-notch impact testing at 20°C, -30°C and -40°C. The purpose of the analysis was to determine the influence of REM on the microstructure and mechanical properties of G20Mn5 cast steel and the REM effect on the morphology, impact strength and character of the fracture surfaces. In addition, a description of the mechanism by which fracture occurred in the two materials was proposed. The author demonstrated the beneficial effects of adding REM to molten steel, manifested by a 20 - 40% increase in impact toughness, depending on test temperature, as compared to the non-modified cast steel. Important findings included more than 100% increase in impact strength in comparison with the required impact toughness of 27J at -40C for heat treated steels (EN 10213).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Numerical prediction of the effects of miniature channel shaped scratches on the fracture behaviour of wires for civil engineering applications using finite element analysis
Autorzy:: Adewole, K. K.
Bull, S. J.
Tematy:: drut
analiza awarii
analiza elementów skończonych
pękanie
zarysowanie
wire
failure analysis
finite element analysis
fracture analysis
scratch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/231418.pdf Link otwiera się w nowym oknie
Opis:: The effects of the miniature channel-shaped scratches not detectable by the present inline electromagnetic defect detection system employed for wires’ surface defect detection on the fracture behaviour of the wires for civil engineering applications were investigated numerically. Finite element analysis revealed that both miniature channel-shaped across-the-thickness and across-the-width scratches change the fracture behaviour of the wires in terms of the fracture initiation locations and fracture process sequence. However, miniature across-the-thickness scratches does not affect the fracture shape of the wire while miniature across-the-width scratches changed the wires’ cup and cone fracture to a fracture shape with a predominantly flat fracture. These results provide an understanding of the fracture behaviour of wires with miniature scratches and serve as an alternative or a complimentary tools to experimental or fractographic failure analysis of wires with miniatures scratches which are difficult to carry out in the laboratory due to the sizes of the scratches.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Mechanical properties and fracture analysis of AlCu4MgSi alloy ingots obtained by horizontal continuous casting
Autorzy:: Nuckowski, P. M.
Wróbel, T.
Tematy:: AlCu4MgSi alloy
horizontal continuous casting
fracture analysis
mechanical properties of ingots
aluminum; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/352196.pdf Link otwiera się w nowym oknie
Opis:: The article presents the results of research concerning AlCu4MgSi alloy ingots produced using horizontal continuous casting process under variable conditions of casting speed and cooling liquid flow through the crystallizer. The mechanical properties and structure of the obtained ingots were correlated with the process parameters. On the basis of the obtained results, it has been shown that depending on the cooling rate and the intensity of convection during solidification, significant differences in the mechanical properties and structure and of the ingots can occur. The research has shown that, as the casting speed and the flow rate of the cooling liquid increase, the hardness of the test samples decreases, while their elongation increases, which is related to the increase of the average grain size. Also, the morphology of the intermetallic phases precipitations lattice, as well as the centerline porosity and dendrite expansion, significantly affect the tensile strength and fracture mechanism of the tested ingots.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Optimization of process parameters of friction stir welded AA5082-AA7075 butt joints using resonance fatigue properties
Autorzy:: Kumar, G.
Kumar, R.
Tematy:: friction stir welding
dissimilar Al welding
resonance fatigue analysis
fracture surface analysis
ANOVA; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/200299.pdf Link otwiera się w nowym oknie
Opis:: In this work, experiments were carried out to quantify the behaviour of friction stir welded (FSW) AA5082-AA7075 butt joints under tensile loading and completely reversed fatigue loading. Different samples were prepared to identify optimum tool rotational and travel speeds to produce FSW AA5082-AA7075 butt joints with the maximum fatigue life. ANOVA was performed, which confirmed that both tool speed nad tool rotation speed affect the tensile strength of the weld. The samples exhibit a considerable difference in their fatigue life and tensile strenght. This difference can be accounted to the presence of welding defects such as surface defects and porosity. S-N curve plotted for the sample shows a significantly high fatigue life at the lower stress ranges. Fracture surfaces were also analysed under scanning electron microscope (SEM). Study of the fracture surface of the sample that failed under fatigue loading showed that the surface was mainly divided in two zones. The first zone was the area of fatigue crack growth where each stress cycle, slowly and gradually, helped in the growth of crack. The second zone was the region of fast fracture where the crack growth resulted in the failure of the joint instantaneously. The fracture surface study of the sample that failed under tensile loading showed that the mode of failure was ductile in nature.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Structure and Properties of Mg-Cu-(Y,Ca) Bulk Metallic Glasses
Struktura i własności masywnych szkieł metalicznych Mg-Cu-(Y,Ca)
Autorzy:: Babilas, R.
Cesarz-Andraczke, K.
Nowosielski, R.
Tematy:: Mg-based alloys
bulk metallic glasses
thermal analysis
fracture analysis
mechanical properties
masywne szkła metaliczne
związki magnezu
analiza termiczna
analiza pękania
właściwości mechaniczne; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/355924.pdf Link otwiera się w nowym oknie
Opis:: The work presents preparation methods, structure characterization and mechanical properties analysis of Mg-based bulk metallic glasses in as-cast state and after crystallization process. The studies were performed on Mg₆₀Cu₃₀Y₁₀ and Mg₃₇Cu₃₆Ca₂₇ glassy alloys in the form of plates and rods. The X-ray diffraction investigations revealed that the tested samples with different thicknesses and shapes were amorphous. The characteristics of the fractured surfaces showed mixed fractures with the “river” and “mirror” patterns, which are characteristic for the glassy materials and some “smooth” areas. The samples of Mg₃₇Cu₃₆Ca₂₇ alloy presented a two-stage crystallization process, but addition of Y caused a single stage crystallization behavior. Qualitative phase analysis from the X-ray data of examined alloys annealed at 473 K enabled the identification of Mg, Mg₂Cu, Cu₂Mg and CaCu crystalline phases. The changes of compressive strength as a function of annealing temperature for studied rods were stated. The best mechanical properties including microhardness and compressive strength were obtained for the alloy with the addition of Y in as-cast state.
W pracy przedstawiono wyniki badań struktury i wybranych własności masywnych szkieł metalicznych na osnowie magnezu. Badania przeprowadzono na próbkach w stanie wyjściowym oraz po procesie wygrzewania. Do badań wybrano dwa trójskładnikowe stopy magnezu z dodatkiem itru lub wapnia o następującym składzie chemicznym:Mg₆₀Cu₃₀Y₁₀ oraz Mg₃₇Cu₃₆Ca₂₇. Badania rentgenowskie potwierdziły, że analizowane próbki w postaci płytek i prętów posiadają strukturę amorficzną. Obserwacje mikroskopowe wybranych obszarów powierzchni przełomów płytek i prętów pozwoliły na wyodrębnienie stref o morfologii przełomów „gładkich” i „łuskowych”. Analiza procesu krystalizacji wykazała występowanie pojedynczego etapu krystalizacji dla szkła metalicznego Mg₆₀Cu₃₀Y₁₀ związanego z wydzielaniem się fazy Mg₂Cu oraz dwuetapowego procesu krystalizacji dla stopu Mg₃₇Cu₃₆Ca₂₇, w którym zidentyfikowano fazę Cu₂Mg i CaCu. Największą wytrzymałość na ściskanie oraz mikrotwardość uzyskano dla próbek szkła metalicznego z dodatkiem itru w stanie bezpośrednio po odlaniu.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Forensic significance of perforation pattern in polycarbonate sheet against 9 × 19 mm projectile
Znaczenie układu perforacji na płycie poliwęglanowej po uderzeniu pociskiem 9 × 19 mm w badaniach kryminalistycznych
Autorzy:: Prajapati, Abhishek
Kumar, Saurabh
Rohatgi, Richa
Jaitly, Tamanna
Aseri, Vinay
Tematy:: Forensic significance
Perforation pattern
Polycarbonate sheet
9 × 19 mm full metal jacket projectile
Ballistic impact
Fracture analysis; Pokaż więcej
Wydawca:: Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Powiązania:: https://bibliotekanauki.pl/articles/59896599.pdf Link otwiera się w nowym oknie
Opis:: Polycarbonate is widely used as structural material due to its extreme resistance to impact and perforation. In a crime involving firearms, the bullet may impact various objects fitted with or made of polycarbonate sheets leaving high chances of discovering the fractured PC sheets and fragments at the scene of crime; hence, these objects may become objects of the criminal investigation. In the present work the perforation pattern of PC sheets of thicknesses 8 mm, 10 mm, 12 mm and 15 mm at firing ranges 5 m and 10 m when impacted against 9 ×19 mm full metal jacket (FMJ) bullet were examined. It was observed that after impact, the PC sheet develops entry hole smaller than the calibre of bullet; formation of crack zone, plastic zone; and petalling on the distal face was observed. It was found that as the thickness of the sheet increases, the diameter of the entry hole increases, the diameter of the exit hole initially increases and then becomes constant. At 5 m range of fire the trend of crack zone becomes nearly constant from 8 mm to 15 mm thickness, however, at 10 m range of fire crack zone increases from 8 mm to 15 mm thickness. Furthermore, the diameter of the plastic zone increases as the thickness of the sheet increases (from 8 mm to 15 mm, respectively).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Higher milk consumption is not associated with fracture risk reduction: systematic review and meta-analysis
Autorzy:: Goncerz, Grzegorz
Kojm, Patrycja
Skocelas, Sylwia
Więckowski, Krzysztof
Gallina, Tomasz
Pietrzyk, Paulina
Goncerz, Sebastian
Tematy:: milk
fracture
meta-analysis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/57065156.pdf Link otwiera się w nowym oknie
Opis:: Introduction: Osteoporosis affects over 200 million people worldwide causing nearly 9 million fractures annually, with more than half in America and Europe. Objectives: This meta-analysis was conducted to investigate whether low milk intake is associated with an increased risk of fractures by summarizing all the available evidence. Methods: Relevant studies were identified by searching the PubMed and EMBASE databases up to June 2020. The pooled relative risks with 95% confidence intervals were calculated. Results: In a meta-regression analysis of 20 included studies (11 cohort and 9 case-control studies), a higher milk intake was not associated with a reduction in the total fracture risk in both sexes (OR 0.95, 95% CI: 0.84– 1.08), either in cohort (OR 0.91; 95% CI: 0.79–1.05) or case-control studies (OR 1.09; 95% CI: 0.82–1.44), as well as separately in men (OR 0.87; 95% CI: 0.71–1.07) and women (OR 0.95; 95% CI: 0.80–1.13). Conclusion: Higher milk consumption is not associated with fracture risk reduction and should not be recommended for fracture prevention.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Ductile fracture criterion for specimens with notches made of aluminium alloy EN-AW 2024
Autorzy:: Derpeński, Ł.
Seweryn, A.
Tematy:: numerical analysis
fracture of specimen with notches
ductile fracture criterion; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/280994.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the experimental verification of the most frequently used ductile fracture criteria based on authors own experimental results and numerical calculations. Attention is drawn to the large discrepancy of results of fracture prediction and experimental data for six considered criteria. Based on own results, a new ductile fracture criterion for notched specimens is proposed. In the criterion, it is assumed that fracture initiation occurs when the maximum normal stress reaches a critical value depending on the maximum value of plastic shear strain.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: A two-dimensional finite element analysis of the influence of fracture gap and angle on bone healing process
Autorzy:: Prochor, Piotr
Taraszewicz, Patrycja
Tematy:: numerical analysis
bone
fracture
secondary healing
evaluation algorithm; Pokaż więcej
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Powiązania:: https://bibliotekanauki.pl/chapters/2215580.pdf Link otwiera się w nowym oknie
Opis:: Over the years, many mechanoregulation concepts of fracture healing have been developed. They all assume that higher values of the stimulus in the fracture gap cause the formation of a fibrous tissue and only lower values can lead to the formation of bone tissue. A literature review of the numerical evaluation of bone fracture healing has revealed some shortcomings in the existing studies. Scientists often focus on only one of the three phases of fracture healing. In addition, studies are often carried out with the use of only transverse fractures. The aim of the study is to develop an algorithm for the numerical evaluation of bone fracture healing, which can be used for both transverse as well as oblique fractures. To conduct the research, the authors proposed an algorithm that considers all phases occurring in secondary healing: 1 – hematoma formation, 2 – tissue differentiation, 3 – bone tissue remodeling. Appropriate CAD models of simplified fracture were designed that additionally considered two variables: fracture angle (from 0° to 45°) and fracture gap (from 2.5 mm to 10.0 mm). Axial loading was used in order to generate mechanobiological stimulus. The obtained results presented a significant influence of the analyzed variables on the studied process. This proved that the designed algorithm can be used to speed up the treatment process and enable designing a more effective rehabilitation procedure for an individual patient.
Dostawca treści:: Biblioteka Nauki

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