Epoxy Adhesives Modified With Nano- and Microparticles for In Situ Timber Bonding: Fracture Toughness Characteristics

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Z. Ahmad ◽  
M. P. Ansell ◽  
D. Smedley
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Single Edge ◽  
Notched Specimens ◽  
Epoxy Adhesives ◽  
Adhesive Formulation ◽  
Made In

Adhesives used for bonded-in steel or composite pultruded rods and plate to make connections in timber structures are commonly room temperature cure adhesives. The room temperature cure, applied without pressure, thixotropic, and shear thinning characteristics of the adhesives, is for ease of application when repairs and reinforcement are being made in situ in the field. The room temperature cure adhesive may not fully cross-link and this may cause brittleness. Therefore to improve the toughness properties of such adhesives, nanoparticles can be added. This paper reports the experimental investigation carried out on the fracture toughness of three thixotropic and room temperature cured epoxy-based adhesives formulated specifically for in situ timber bonding, namely, CB10TSS (standard adhesive), Albipox is CB10TSS with the addition of nanodispersed carboxyl-terminated butadiene acrylonitrile (CTBN), and Timberset is an adhesive formulation containing ceramic microparticles. The fracture toughness behavior of the adhesives was investigated using the Charpy impact test on unnotched and notched specimens conditioned at 20∘C/65%RH to evaluate notch sensitivity, and a single-edge notched beam (SENB) test was performed to evaluate the stress intensity factor KIC. The fracture surfaces were investigated using scanning electron microscopy. Under high impact rate, toughness was in the order of CB10TSS, Albipox, and Timberset. CB10TSS and Albipox were found to be ductile in the unnotched state and brittle when notched. Timberset was brittle in both unnotched and notched states. Under low strain rate (SENB) conditions the addition of CTBN significantly improved the fracture toughness of Albipox compared with CB10TSS and Timberset. Examination of the topography of the fractured surface revealed marked changes in crack propagation due to the addition of nano- or microfillers accounting for the variation in toughness properties.

scholarly journals EPOXY/TITANATE MODIFIED NANOSILICA COMPOSITES: MORPHOLOGY, MECHANICAL PROPERTIES AND FRACTURE TOUGHNESS

2018 ◽  
Vol 56 (2A) ◽  
pp. 133-140
Author(s):  
Ho Ngoc Minh
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Bending Test ◽  
Tetrabutyl Titanate ◽  
Single Edge ◽  
Modified Silica ◽  
Three Point Bending

In this paper, the effect  of modified nanosilica as a reinforcement agent on the performance of epoxy resin using tetrabutyl titanate (TBuT) hardener were investigated. Morphology of the epoxy/modified silica composites was determined by Scanning Electron Microscopy (SEM) method. Impact strength and flexural strength of the composites were measured by Charpy impact test and three-point bending test mode methods, respectively. Fracture toughness and fracture energy were calculated according to pre-cracked, single edge notched method with specimens in three-point bending geometry and suitable equations. The mechanical properties and fracture toughness of composites were significantly enhanced with loading nanosilica content to 5 wt.%. 

Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 255-260 ◽  
Author(s):  
G. Zhang ◽  
L. Hu ◽  
W. Hu ◽  
G. Gottstein ◽  
S. Bogner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Creep Resistance ◽  
Room Temperature ◽  
Growth Direction ◽  
Nominal Composition ◽  
Potential Candidate ◽  
In Situ Composites

ABSTRACTMo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

A Study on Material Degradation in Carbon Steel for Pressure Vessel at 179°C

2006 ◽  
Vol 321-323 ◽  
pp. 532-535
Author(s):  
Un Bong Baek ◽  
Jong Seo Park ◽  
Seung Hoon Nahm ◽  
Hyuck Mo Lee
Keyword(s):  
Carbon Steel ◽  
Room Temperature ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Life Assessment ◽  
Material Degradation ◽  
Ductile To Brittle Transition ◽  
Industrial Boilers ◽  
Micro Structures ◽  
Degradation Time

In spite of frequent defect in industrial boilers, life assessment or diagnostic method for them has not been studied. In this research, SB410 carbon steel used in industrial boilers is simulated with artificial aging heat treatment. To do qualitative life assessment, differences in micro-structures and hardness of SB410 by the degradation time are studied. In addition, variation in material properties by aging was observed with the tensile test at room temperature and 179 °C and changes in ductile to brittle transition temperature was observed with the charpy impact test performed at several test temperature.

scholarly journals The Charpy Impact Test of Rock (2nd Report)-Dynamic Fracture Toughness-

2006 ◽  
Vol 18 (1/2) ◽  
pp. 15-20
Author(s):  
Mitsumasa FURUZUMI ◽  
Fumio SUGIMOTO ◽  
Tadao IMAI ◽  
Naoto KAMOSHIDA ◽  
Masayoshi ABE
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Dynamic Fracture Toughness

The Temperature Dependence of Yield Stress and Fracture Toughness in Unstabilized Zirconia Crystals

1986 ◽  
Vol 78 ◽  
Author(s):  
T. W. Coyle ◽  
R. P. Ingel ◽  
P. A. Willging
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Test Temperature ◽  
Room Temperature ◽  
Single Edge ◽  
Melting Technique ◽  
Strength Tests ◽  
Edge Notch

ABSTRACTThe flexural strength and the single edge notch beam fracture toughness of undoped ZrO2 crystals, grown by the skull melting technique, were examined from room temperature to 1400°C. On heating the toughness increased with test temperature to a maximum of 4.0 MPajm at 1225°C then gradually decreased to 2.6 MPa/m. Upon cooling after a 20 minute hold at 1250°C an increase in toughness to 5 MPa/m was observed at 1200°C; upon cooling to lower temperatures Kic gradually diminished. The loaddeflection curves for the flexural strength tests showed marked nonlinearity before failure for samples tested on cooling. The temperature dependence of the apparent yield stress suggests that initial yielding occurs by slip above 1200°C but that from 1200°C to 1050°C the observed yielding is due to stress induced tetragonal to monoclinic transformation.

Notch Effects on Room Temperature Tensile and Bend Properties of Ni3Al and Ni3Al+B

1988 ◽  
Vol 133 ◽  
Author(s):  
P. S. Khadkikar ◽  
J. D. Rigney ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Stress ◽  
Room Temperature ◽  
Tensile Tests ◽  
Boron Addition ◽  
Notched Specimens ◽  
Grain Boundary Fracture ◽  
Bend Tests ◽  
Boundary Fracture

ABSTRACTThe notched mechanical properties of Ni3AI and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Ten- sile tests performed using double notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3AI+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Synthesis and Properties of In-Situ MoSi2/SiC Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
S. Jayashankar ◽  
S.E. Riddle ◽  
M. J. Kaufman
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Indentation Fracture ◽  
Processing Scheme ◽  
Indentation Fracture Toughness ◽  
Novel Processing ◽  
Sic Composites

AbstractCompositionally-tailored, silica-free, MoSi2/SiC composites with SiC content ranging from 0 to 40 percent were synthesized through a novel processing scheme involving mechanical alloying and in-situ reactions for the formation of the reinforcement. Room temperature indentation fracture toughness and hardness measurements were obtained from these silica-free composites and were compared with values obtained from silica-containing, conventionally-processed MoSi2/SiC composites.

Evaluation of Fracture Toughness From Instrumented Charpy Impact Tests for a Reactor Pressure Vessel Steel

2003 ◽  
Author(s):  
A. Parrot ◽  
P. Forget ◽  
A. Dahl
Keyword(s):  
Fracture Toughness ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Impact Tests ◽  
Reactor Pressure Vessel Steel ◽  
Ductile To Brittle Transition ◽  
Reactor Pressure

The monitoring of neutron induced embrittlement of nuclear power plants is provided using Charpy impact test in the surveillance program. However structural integrity assessments require the fracture toughness. Some empirical formulas have been developed but no direct relationship was found. The aim of our study is to determine the fracture toughness of a Reactor Pressure Vessel steel from instrumented Charpy impact test using local approach to fracture. This non-empirical method has been applied in the brittle domain as well as in the ductile to brittle transition for an A508 C1.3 steel. In the brittle domain, fracture occurs by cleavage and can be modeled with the Beremin model. Fracture toughness has been successfully determined from Charpy impact tests results and the influence of several parameters (mesh design, Beremin model with one or two parameters, number of Charpy impact tests results) on the results was considered. In the ductile to brittle transition, cleavage fracture is preceded by ductile crack growth. Ductile tearing has been accounted for in the simulations with the Rousselier model whereas cleavage fracture is still described with the Beremin model. The determination of fracture toughness from Charpy impact tests gave encouraging results but finite element simulations have to be refined in order to improve predictions.

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