scholarly journals Load-Displacement Measurement and Work Determination in Three-Point Bend Tests of Notched or Precracked Specimens

1978 ◽  
Vol 6 (1) ◽  
pp. 35 ◽  
Author(s):  
RT Horstman ◽  
KC Lieb ◽  
RL Meltzer ◽  
IC Moore ◽  
RJ Buzzard ◽  
...  
Keyword(s):  
Displacement Measurement ◽  
Bend Tests ◽  
Load Displacement ◽  
Point Bend

Acoustic Emission Studies of Alumina-13% Titania Free-Standing Forms during Four-Point Bend Tests

2005 ◽  
Vol 80 (9) ◽  
pp. 2382-2394 ◽  
Author(s):  
Chung-Kwei Lin ◽  
Christopher C. Berndt ◽  
Sang-Ha Leigh ◽  
Kenji Murakami
Keyword(s):  
Acoustic Emission ◽  
Free Standing ◽  
Bend Tests ◽  
Point Bend ◽  
Emission Studies

Effects of Dynamic Strain-Aging and Cyclic Loading on Fracture Behavior of Ferritic Steels

2002 ◽  
Author(s):  
K. Linga Murty ◽  
Chang-Sung Seok
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Strain Aging ◽  
Crack Tip ◽  
Load Ratio ◽  
Seismic Loading ◽  
Dynamic Strain ◽  
Ferritic Steels ◽  
Bend Tests ◽  
Point Bend

Ferritic steels commonly used for pressure vessels and reactor supports in light water reactors (LWRs) exhibit dynamic strain aging (DSA) resulting in decreased ductility and toughness. In addition, recent work indicated decreased toughness during reverse-cyclic loading that has implications on reliability of these structures under seismic loading conditions. We summarize some of our recent work on these aspects along with synergistic effects, of interstitial impurity atoms (IIAs) and radiation induced point defects, that result in interesting beneficial effects of radiation exposure at appropriate temperature and strain-rate conditions. Radiation-defect interactions were investigated on pure iron, Si-killed mild steel, A533B, A516, A588 and other reactor support and vessel steels. In all cases, DSA is seen to result in decreased ductility accompanied by increased work-hardening parameter. In addition to mechanical property tests, fracture toughness is investigated on both A533B and A516 steels. While dips in fracture toughness are observed in A533B steel in the DSA region, A516 steel exhibited at best a plateau. The reasons could lie in the applied strain-rates; while J1c tests were performed on A533B steel using 3-point bend tests on Charpy type specimens, CT specimens were used for A516 steel. However, tensile and 3-point bend tests on similar grade A516 steel of different vintage did exhibit distinct drop in the energy to fracture. Load-displacement curves during J1c tests on CT specimens did show load drops in the DSA regime. The effect of load ratio (R) on J versus load-line displacement curves for A516 steel is investigated from +1 to −1 at a fixed normalized incremental plastic displacement of 0.1 (R = 1 corresponds to monotonic loading). We note that J-values are significantly reduced with decreasing load ratio. The work-hardening characteristics on the fracture surfaces were studied following monotonic and cyclic loading fracture tests along with the stress-field analyses. From the hardness and the ball-indentation tests, it was shown that decreased load ratio (R) leads to more strain hardening at the crack tip resulting in decreased fracture toughness. From the stress field analysis near the crack tip of a compact tension fracture toughness test specimen, a cycle of tensile and compressive loads is seen to result in tensile residual stresses (which did not exist at the crack tip before). These results are important to evaluations of flawed-structures under seismic loading conditions, i.e. Leak-Before-Break (LBB) and in-service flaw evaluation criteria where seismic loading is addressed. In addition, studies on fast vs total (thermal+fast) neutron spectra revealed unexpected results due to the influence of radiation exposure on source hardening component of the yield stress; grain-size of pure iron plays a significant role in these effects.

Fracture energy for three-point-bend tests on single-edge-notched beams

1988 ◽  
Vol 28 (3) ◽  
pp. 266-272 ◽  
Author(s):  
L. J. Malvar ◽  
G. E. Warren
Keyword(s):  
Fracture Energy ◽  
Single Edge ◽  
Bend Tests ◽  
Point Bend

scholarly journals Role of Microstructure in Susceptibility of X70 Pipeline Steel to Hydrogen Embrittlement

2010 ◽  
Vol 654-656 ◽  
pp. 162-165 ◽  
Author(s):  
D. Hejazi ◽  
A.J. Haq ◽  
N. Yazdipour ◽  
D.P. Dunne ◽  
Frank J. Barbaro ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Fracture Surface ◽  
Heat Affected Zone ◽  
Pipeline Steel ◽  
Rolled Strip ◽  
Bend Tests ◽  
Point Bend ◽  
Hot Rolled ◽  
Surface Observations

In order to investigate the susceptibility of steels to hydrogen embrittlement as a function of their microstructure X70 steel was chosen in different conditions: normalized transfer bar, as-received hot rolled strip and heat affected zone (HAZ). Notched and fatigue pre-cracked samples were subjected to electrochemical hydrogen charging to achieve 2 ppm hydrogen content. Three point bend tests were conducted on as-received and hydrogen charged samples. The results showed that HAZ samples are more susceptible to hydrogen embrittlement than the others. This was supported by fracture surface observations.

Biomimetic model of a sponge-spicular optical fiber—mechanical properties and structure

2001 ◽  
Vol 16 (5) ◽  
pp. 1420-1428 ◽  
Author(s):  
M. Sarikaya ◽  
H. Fong ◽  
N. Sunderland ◽  
B. D. Flinn ◽  
G. Mayer ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Optical Fibers ◽  
Circular Cross Section ◽  
Fused Silica ◽  
Atomic Force ◽  
Commercial Glass ◽  
Bend Tests ◽  
Point Bend ◽  
Thick Layers

Nanomechanical properties, nanohardness and elastic modulus, of an Antarctic sponge Rosella racovitzea were determined by using a vertical indentation system attached to an atomic force microscope. The Rosella spicules, known to have optical waveguide properties, are 10–20 cm long with a circular cross section of diameter 200–600 μm. The spicules are composed of 2–10-μm-thick layers of siliceous material that has no detectable crystallinity. Measurements through the thickness of the spicules indicated uniform properties regardless of layering. Both the elastic modulus and nanohardness values of the spicules are about half of that of either fused silica or commercial glass optical fibers. The fracture strength and fracture energy of the spicules, determined by 3-point bend tests, are several times those of silica rods of similar diameter. These sponge spicules are highly flexible and tough possibly because of their layered structure and hydrated nature of the silica. The spicules offer bioinspired lessons for potential biomimetic design of optical fibers with long-term durability that could potentially be fabricated at room temperature in aqueous solutions.

Analysis of composite stiffener under successive impact and bending test

2017 ◽  
Vol 36 (17) ◽  
pp. 1225-1238 ◽  
Author(s):  
Muhammad Ridha ◽  
Tong-Earn Tay ◽  
Sven Werner ◽  
Paul Joern ◽  
Vincent Beng Chye Tan
Keyword(s):  
Experimental Investigation ◽  
Impact Strength ◽  
Bending Strength ◽  
Impact Damage ◽  
Experimental Tests ◽  
Bending Test ◽  
Successful Prediction ◽  
Bend Tests ◽  
Point Bend ◽  
Extent Of Damage

In this article, we present the analysis, modelling and experimental investigation of composite omega stiffeners from non-penetrating impact to bending-after-impact. We used advanced computational methods to determine the extent of damage due to impact and, without many simplifications to the damage, predict the residual bending-after-impact strength under four-point-bend tests. The predicted sizes and patterns of impact damage, and the subsequent predicted bending strengths are compared to experimental tests of omega stiffeners. This work shows that preserving the details and fidelity of damage in the computational model is critical to successful prediction of residual strength. It was also found that modifying the design of the stiffeners by changing the orientation of some of the plies reduces the extent of impact damage and increases residual bending strength.

scholarly journals A Levenberg-Marquardt algorithm for fi tting σ-w curves from three-point bend tests for plain and fi ber reinforced concretes

2011 ◽  
Vol 4 (4) ◽  
pp. 691-694 ◽  
Author(s):  
J.L.A.O. Sousa
Keyword(s):  
Inverse Analysis ◽  
Technical Note ◽  
Fiber Reinforced ◽  
Notched Specimens ◽  
Marquardt Algorithm ◽  
Levenberg Marquardt ◽  
Bend Tests ◽  
Point Bend

This technical note describes the implementation of the Levenberg-Marquardt algorithm for the inverse analysis of three-point bend tests on notched specimens of plain and fiber reinforced concretes for determining softening parameters (σ-w curves). Tests indicated that the algorithm is sufficiently efficient and robust.

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