Elastic Waves Created During Tensile Fracture: The Phenomenon of a Second Fracture

1953 ◽  
Vol 20 (1) ◽  
pp. 122-130
Author(s):  
Julius Miklowitz
Keyword(s):  
Cross Sections ◽  
Tensile Tests ◽  
Analog Computer ◽  
Tensile Fracture ◽  
Strain Waves ◽  
Unloading Wave ◽  
Second Fracture ◽  
Wave Compression ◽  
Initial Fracture ◽  
The Moment

Abstract In some tensile tests with brittle materials, it was noted that fractures were produced at two different cross sections of the specimen when the rupture load was reached. The phenomenon of the second fracture prompted the present investigation. It is believed that the second fracture is caused by the destructive action of the elastic strain waves created during the first of the two fractures. The analytical and experimental work carried out was focused on describing the character of these waves. Consideration of the mechanics involved reduces the problem to that of a vibrating cantilever beam with time-dependent boundary conditions. Two types of waves are shown to exist. The first is a longitudinal unloading wave (compression). The other is a group of flexural strain waves caused by the moment that develops at the initial fracture section. The methods of operational mathematics and the electric-analog computer have been employed in the analytical study.

scholarly journals Research of crack initiation in tension test specimen made of nickel alloy EI961sh

2018 ◽  
Vol 165 ◽  
pp. 22027
Author(s):  
Kamaliddin Karimbaev ◽  
Ivan Pleshcheev ◽  
Elena Bredihina
Keyword(s):  
Cross Sections ◽  
Test Specimen ◽  
Plastic Material ◽  
Tensile Tests ◽  
Deformation Energy ◽  
Experimental Fact ◽  
Conservation Of Energy ◽  
Software Complex ◽  
The Moment ◽  
Cylindrical Test

In this paper method of numerical computations using explicit scheme, implemented in LSDyna (Ansys) software complex, is introduced and verified. Obtained solution explains experimental fact mentioned by P. Ludwik, that cracking in cylindrical test specimen made of plastic material starts in the middle of the smallest cross-section of the specimen. Introduced method allows verifying law, obtained by N.N. Davidenkov during unique experimental research in which he studied logarithmic strain in specimen’s neck by pickling of cross-sections in this zone. Additionally it is possible to estimate amount of heat, generated during rupture of specimen, using obtained solution and law of conservation of energy. For this purpose tensile tests, in which thermal camera was used for temperature measuring, were conducted. It was shown, that all deformation energy apart from elastic and shape-forming energy in volume element, calculated in the moment before rupture is transformed to heat. Also tensile tests with various rate of loading were conducted for more detailed research of rupture process.

scholarly journals APPLICATION OF DOMAIN INTEGRATED DESIGN METHODOLOGY FOR BIO-INSPIRED DESIGN- A CASE STUDY OF SUTURE PIN DESIGN

2021 ◽  
Vol 1 ◽  
pp. 487-496
Author(s):  
Pavan Tejaswi Velivela ◽  
Nikita Letov ◽  
Yuan Liu ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Cross Sections ◽  
Design Methodology ◽  
Reaction Force ◽  
Integrated Design ◽  
Total Deformation ◽  
Insertion Force ◽  
Force Reaction ◽  
The Moment ◽  
Work Done

AbstractThis paper investigates the design and development of bio-inspired suture pins that would reduce the insertion force and thereby reducing the pain in the patients. Inspired by kingfisher's beak and porcupine quills, the conceptual design of the suture pin is developed by using a unique ideation methodology that is proposed in this research. The methodology is named as Domain Integrated Design, which involves in classifying bio-inspired structures into various domains. There is little work done on such bio-inspired multifunctional aspect. In this research we have categorized the vast biological functionalities into domains namely, cellular structures, shapes, cross-sections, and surfaces. Multi-functional bio-inspired structures are designed by combining different domains. In this research, the hypothesis is verified by simulating the total deformation of tissue and the needle at the moment of puncture. The results show that the bio-inspired suture pin has a low deformation on the tissue at higher velocities at the puncture point and low deformation in its own structure when an axial force (reaction force) is applied to its tip. This makes the design stiff and thus require less force of insertion.

Microstructure and Tensile Behavior of Ti-Rich Ti-Ni-Cu Melt-Spun Ribbon

2014 ◽  
Vol 936 ◽  
pp. 1163-1167
Author(s):  
Wen Jun He ◽  
Guang Hui Min ◽  
Oleg Tolochko
Keyword(s):  
Melt Spinning ◽  
Tensile Deformation ◽  
Amorphous Ribbon ◽  
Fracture Morphology ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Annealed Ribbon ◽  
Martensitic State

Microstructure and mechanical properties of Ti51.5Ni25Cu23.5 ribbon fabricated by melt spinning were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and tensile tests. Some B19 martensite crystalline with (011) compound twin was embedded in the mainly amorphous ribbon, while the ribbon annealed at 450°C for 1 h is at fully martensitic state. Annealing process alter the preferential orientation from (022)-B19 to (111)-B19. Tensile fracture stresses of as-spun ribbon and the annealed ribbon are 1257 MPa and 250 MPa, respectively. The tensile fracture morphology of as-spun ribbon shows typical vein fringe while that of the annealed ribbon reveals fine but depth-inhomogeneous dimples. After tensile deformation, the annealed ribbon exhibits typical martensitic detwinning behavior accompanying with the strain contrast.

Yb:YAG Disc Laser Welding of Austenitic Stainless Steel Without Filler Material

2009 ◽  
Vol 410-411 ◽  
pp. 87-96 ◽  
Author(s):  
Markku Keskitalo ◽  
Kari Mäntyjärvi
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cross Sections ◽  
Base Material ◽  
Tensile Tests ◽  
Solidification Cracking ◽  
Filler Material ◽  
Test Material ◽  
Butt Weld

The laser weldability of austenitic stainless steel (ASS) is good because of the material’s high absorptivity and favourable microstructure. There can be a slight possibility of solidification cracking at high welding speeds and low Crekv/Niekv ratios. Test welds were welded with a Yb:YAG disc laser. The test material was 3.2 mm EN 1.4404 2H C700 type stainless steel plate which was work hardened by cold rolling. The test materials were welded with different heat inputs ranging from 0.024 kJ/mm to 0.12 kJ/mm and with 300 mm and 200 mm focal lengths. The weld seams were square-groove welded as butt weld without filler material. The edges of the groove were made by mechanical or laser cutting. The hardness profiles from cross-sections of the welds were measured with a Vickers microhardness tester using 200 g weight. The mechanical properties were tested with tensile tests. The welds were classified with radiographic verification by an accredited laboratory. A number of the welds were fatigue tested with a bending fatigue tester. The mechanical properties (Rp 0.2%, Rm) of the laser welds were almost the same as in the base material except at the highest heat input. In the radiographic classification, the welds which were welded to the laser-cut edge were classified as class B (accepted). The other welds were classified as class D or C (rejected). The main reasons for the rejection of welds made on mechanically cut edges were lack of penetration or undercut of the weld. A problem with mechanically cut edges, and hence the welds, is that they can be non-square and bent edge. Fatigue tests and tensile tests gave no evidence of solidification cracking in the microstructure of the solidified parts of the welds.

Fatigue Properties of Al-Li Plates Joined by Friction Stir Welding

2008 ◽  
Vol 385-387 ◽  
pp. 849-852 ◽  
Author(s):  
Pasquale Cavaliere ◽  
Francesco W. Panella ◽  
Antonio Squillace
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Testing Machine ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Control Mode ◽  
Fatigue Properties ◽  
Amplitude Control ◽  
Friction Stir

Al-Li alloys are characterized by a strong anisotropy in mechanical properties and microstructure with respect to the rolling direction. Plates of 2198 Al-Li alloy were friction stir welded by employing maximum rotation speed: 1000 rev/min and welding speed of 80 mm/min, both in parallel and orthogonal directions with respect to the rolling one. The joints mechanical properties were evaluated by means of tensile tests at room temperature. In addition, fatigue tests performed with a resonant electro-mechanical testing machine under constant amplitude control up to 250 Hz loading, were conducted in axial control mode with R(σmin/σmax)=0.33, for all the welding and rotating speed conditions. The fatigue crack propagation experiments were performed by employing single edge notched specimens.With the aim to characterize the weld performances, both the microstructure evolution at jointed cross sections, related to the welding variables, and the fractured surfaces were respectively analyzed by means of optical and scanning electron microscopy.

The Brittleness of Ebonite

1937 ◽  
Vol 10 (4) ◽  
pp. 778-786
Author(s):  
R. Ariano
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Test Specimen ◽  
The State ◽  
The Other ◽  
Appreciable Effect ◽  
Considerable Influence ◽  
Minimum Depth ◽  
The Moment

Abstract The results of tests of the brittleness of ebonite are described. Resilience is influenced chiefly by the moment of inertia of the cross section of the test-specimen, but it seems also to be affected by the form of the specimen. The state of vulcanization has considerable influence on these mechanical properties within the undercured range, but with thorough vulcanization the state of cure plays no appreciable part. Notching of test-specimens is not of great importance. It diminishes the resilience, but when the tests are compared on a basis of equal moments of inertia of the resistant cross sections, this diminution becomes inappreciable in the case of brittle ebonites. On the other hand, the shape of the notch in ebonites containing no loading ingredients does influence the resilience. With V-shaped notches, the depth of the notch and its angle of aperture influence considerably the resilience of this latter type of ebonite, and notches of minimum depth are sufficient to have an appreciable effect.

Tensile and Creep Properties of the Refractory Nb Base In-Situ Composite

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1608-1614
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Hisatoshi Hirai
Keyword(s):  
Fracture Surface ◽  
Tensile Tests ◽  
Constant Load ◽  
Tensile Creep ◽  
Tensile Fracture ◽  
Creep Tests ◽  
Tensile Fracture Surface ◽  
In Situ Composite ◽  
Temperature Ranges

Niobium-base in-situ composite Nb-18Si-5Mo-5Hf-2C (in mol%) was prepared and heat-treated at 2070 K for 20 hour. The uni-axile tensile tests at high temperature ranges and the constant load tensile creep tests at 1570 K were performed. The specimen tensile-tested at 1470 K exhibited the excellent UTS of 450 MPa, and the brittle to ductile transition temperature is between 1470 and 1670 K. The specimens creep tested showed good creep strength; the stress exponent is about 5. The tensile fracture surface of the in-situ composite is complex and attributed to cleavage of the Nb 5 Si 3, Nb ss / Nb 5 Si 3 interface separation, ductile rupture of the Nb ss and correlations of these. On the otherhand, the fracture surface of creep tested consists of intergranular above 150 MPa and transgranular below 120 MPa with severely deformed Nb ss .

Notched Tensile Fracture of Ti-6Al-6V-2Sn Welds at Elevated Temperature

2009 ◽  
Vol 79-82 ◽  
pp. 1137-1140 ◽  
Author(s):  
Lv Wen Tsay ◽  
C.L. Hsu
Keyword(s):  
Elevated Temperature ◽  
Grain Boundary ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
Boundary Shear ◽  
Dimple Fracture ◽  
Laser Welds ◽  
Fracture Appearance ◽  
Notched Tensile Strength ◽  
Increasing Temperature

The notched tensile tests of Ti-6Al-6V-2Sn laser welds with distinct post-weld heat treatments (PWHTs) were carried out at 150, 300, and 450oC and the results were also compared with the mill-annealed base metal (BM). The BM specimen had the highest notched tensile strength (NTS) among the specimens being tested at room temperature but became the lowest at 450oC. At/above 150oC, all welds showed a decrease in NTS with increasing temperature. The cracks tended to grow along the α / β interface in the BM specimen. The formation of premature fine pores at the grain boundary in the weld with PWHT at 704oC accounted for the intergranular dimple fracture of the specimen. The fracture appearance of the as-welded (AW) and the 482oC-aged (W-482) welds comprised of mainly transgranular dimple and increased the extent of grain boundary shear at elevated temperature.

Influence of Deformation Speed on Fatigue and Tensile Properties of a Ti-Ni-Cu Shape Memory Alloy

1999 ◽  
Vol 604 ◽  
Author(s):  
Y Kishi ◽  
Z. Yajima ◽  
K Shimizu ◽  
M. Asai
Keyword(s):  
Fatigue Life ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Tensile Properties ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Tensile Fracture ◽  
Scanning Calorimetry ◽  
Sinusoidal Waveform ◽  
Deformation Speed

AbstractThe mechanical fatigue life and tensile property of a Ti-41at.%Ni-8.5at.%Cu alloy, which was solution-treated after some thermo-mechanical treatments, were investigated at 370±1 K as a function of deformation speed. The tensile properties were also investigated at 295±1 K as a function of deformation speed. The B2→B19 martensitic transformation start temperature, Ms, of the alloy was determined to be 338 K by a differential scanning calorimetry, while that of the as-rolled alloy could not be determined. Two types of fatigue tests were carried out by using plate-shaped specimens of 3.5 mm width and 1.5 mm thickness with sinusoidal waveform stresses of 20 Hz and 0.5 Hz frequencies being applied respectively. The fatigue life obtained from the 20 Hz tests was superior to that from the 0.5 Hz tests, the former being about 2 times longer than the latter at the same stress level. Tensile tests were performed at three tensilem speeds of 8.3 × 106, 8.3 × 10−5 and 8.3 × 10−3 m/s. In all the stress - strain curves obtained, an apparent yielding was observed after the liner elastic deformation. The apparent yielding is due to the occurrence of martensitic transformation. The critical stress for inducing martensite and tensile fracture stress increased with increasing tensile speed. Therefore, it is clear that fatigue and tensile properties of Ti-Ni-Cu shape memory alloys are strongly affected by not only test temperature but also deformation speed.

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