Short beam three point bend tests in syntactic foams. Part I: Microscopic characterization of the failure zones

2005 ◽  
Vol 98 (2) ◽  
pp. 673-679 ◽  
Author(s):  
Kishore ◽  
Ravi Shankar ◽  
S. Sankaran
Keyword(s):  
Syntactic Foams ◽  
Short Beam ◽  
Bend Tests ◽  
Point Bend

Characterization of the Residual Stresses and Strength of Ceramic-Metal Braze Joints

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Matteo Galli ◽  
John Botsis ◽  
Jolanta Janczak-Rusch ◽  
Gerd Maier ◽  
Udo Welzel
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Finite Element Models ◽  
Plastic Response ◽  
X Ray Diffraction ◽  
Elastoplastic Properties ◽  
Bend Tests ◽  
Point Bend ◽  
Good Agreement

Residual stress relief in ceramic-metal joints produced by active brazing depends primarily on the plastic response of the filler metal. A procedure for the production and mechanical characterization of bulk active filler alloy specimens is developed. In parallel ceramic-metal joints are produced and tested. Residual stresses are measured by X-ray diffraction while the joint strength is assessed by four-point bend tests. The obtained elastoplastic properties of the filler are introduced into finite element models to predict the residual stresses in the joints and their behavior in bending. The results of the simulations show good agreement both with the residual stress measurements and with the results of four-point bend tests.

Mechanical Characterization of Diamond-Like Carbon (DLC) Coated Polycarbonates

1993 ◽  
Vol 308 ◽  
Author(s):  
Alex J. Hsieh ◽  
Paul Huang ◽  
Shankar K. Venkataraman ◽  
David L. Kohlstedt
Keyword(s):  
High Speed ◽  
Mechanical Tests ◽  
Dominant Mode ◽  
Transverse Cracks ◽  
High Speed Impact ◽  
Dlc Coating ◽  
Bend Tests ◽  
Point Bend ◽  
The Impact

ABSTRACTEvaluations of DLC coated polycarbonates have been carried out via high speed projectile impact, three point bend, and continuous microscratch tests. Radial and circumferential microcracks appeared on the back surfaces and near the regions of impact as a result of the high speed impact stresses. Despite the impact, the adhesion of the DLC coating in the area between the cracks remained, except in the immediate vicinity of impact. In the three point bend tests, transverse cracks developed and propagated in the DLC coating when the applied strain reached the fracture limit of the coating. No delamination occurred in the continuous microscratch tests; instead, cracking of the coating was observed in DLC coated polycarbonates. Microcracking was the dominant mode of failure which was consistent in these three diversed mechanical tests. Results of the SEM studies further confirmed microcracking prior to delamination as observed in the high speed impact tested coupons.

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 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

Investigations on Physical and Mechanical Characterization of the Joints Fabricated through Microwave Hybrid Heating Method

2021 ◽  
Vol 105 ◽  
pp. 25-41
Author(s):  
Parminder Singh ◽  
D.R. Prajapati ◽  
Shankar Sehgal
Keyword(s):  
Power Level ◽  
Dissimilar Materials ◽  
Hardness Test ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
Heating Method ◽  
Hybrid Heating ◽  
Microwave Hybrid Heating ◽  
Point Bend

This paper presents the current major research developments and growths in the area of microwave hybrid heating-based joining of similar and dissimilar materials. The study discusses on the different types of specimen materials, susceptor materials, fillers and microwave power level used by researchers for joining process. Comparative studies of joints using different parametric conditions are also mentioned. Physical characterization of joint has been investigated with optical microscope, scanning electron microscope, energy dispersive spectroscopy, electron probe micro analysis, X-ray diffraction and mechanically with hardness test, tensile test, 3-point bend test, impact test. Various methods for design of experiment and optimization are also used to obtain better results. Current study will facilitate the proper choice of input parameters for easy and good joints formation through the microwave hybrid heating method.

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