scholarly journals Apparent vs. True Bond Strength of Steel and PC with Nanoalumina

2015 ◽  
Vol 1129 ◽  
pp. 307-314
Author(s):  
Ala Eddin Douba ◽  
Moneeb Genedy ◽  
Edward Matteo ◽  
John Stormont ◽  
Mahmoud Reda Taha
Keyword(s):  
Bond Strength ◽  
Steel Surface ◽  
Maximum Shear Stress ◽  
Polymer Concrete ◽  
Fe Model ◽  
Shear Tests ◽  
Steel Pipes ◽  
Wellbore Integrity ◽  
Interface Surface ◽  
Slant Shear

The bond of polymer concrete (PC) to a steel surface is a critical aspect in many infrastructure applications. Bond strength can be evaluated through several means including pull-off, flexural, twist-off, and slant shear tests. While pull-off strength tests are the most common method for evaluating bond for PC overlays in bridge and parking structures, slant shear tests are more suitable when vertical rather than horizontal bond lines are used. In this paper, we discuss the use of slant shear tests to examine bond of polymer concrete repair material to steel pipes used to ensure wellbore integrity of abandoned oil wells used for CO2sequestration.Bond strength of Novolac PC incorporating nanoalumina particles to a steel surface was measured using slant shear tests. Different amounts of nanoalumina were used in the PC to improve bond strength without significantly reducing PC flowability. Slant shear testing confirmed the ability of nanoalumina to improve the steel-PC bond strength. A finite element (FE) model using the ABAQUS simulation environment was developed to compare the apparent versus the true bond strength. A cohesive contact element surface was used to simulate bond along the interface line. The FE model showed that the stiffness mismatch between the PC and steel controls the maximum shear stress developed at the interface surface. The true bond strength extracted from the FE model appears to be about twice that of the apparent bond strength.

Shear Strength and Performance of Glass-to-Metal Brazed Joints

2010 ◽  
Vol 118-120 ◽  
pp. 686-690
Author(s):  
Xi Hai Shen ◽  
Chun Xiang Sun ◽  
Li Chun Wang
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Lap Joints ◽  
Holding Time ◽  
Fe Model ◽  
Shear Tests ◽  
Vacuum Brazing ◽  
Brazed Joints ◽  
And Performance ◽  
Kovar Alloy

Vacuum brazing of glass to Kovar alloy was carried out at 670~700°C using Cu-Ni-Sn-P brazing alloy. The holding time ranges from 5min to 30min. The shear stress was tested to evaluate the mechanical property of the vacuum brazed joints. The results showed the maximum shear stress was 11.6MPa when the brazing temperature was 680°C and holding time was 10min. In accordance with the welded structures, the finite element (FE) model of glass-to-metal brazed joints was established. As result, the shear tests on the lap joints in conjunction with FM analysis were used to optimize the glass-to-metal brazing technology. The above results provide the basis of design against damage and reliable estimation of glass-to-metal seals.

scholarly journals Prediction of the Interface Shear Strength between Ultra-High-Performance Concrete and Normal Concrete Using Artificial Neural Networks

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5707
Author(s):  
Changqing Du ◽  
Xiaofan Liu ◽  
Yinying Liu ◽  
Teng Tong
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Ann Model ◽  
Ultra High Performance Concrete ◽  
Shear Tests ◽  
Research Papers ◽  
Artificial Neural ◽  
Modified Formula ◽  
Slant Shear

The bond strength between ultra-high-performance concrete (UHPC) and normal-strength concrete (NC) plays an important role in governing the composite specimens’ overall behaviors. Unfortunately, there are still no widely accepted formulas targeting UHPC–NC interfacial strength, either in their specifications or in research papers. To this end, this study constructs an experimental database, consisting of 563 and 338 specimens for splitting and slant shear tests, respectively. Moreover, an additional 35 specimens for “improved” slant shear tests were performed, which could circumvent concrete crushing and trigger interfacial debonding. Additionally, for the first time in our tests, the effect of casting sequence on UHPC–NC bond strength was identified. Based on the database, an artificial neural network (ANN) model is proposed with the following inputs: namely, the normal stress perpendicular to the interface, the interface roughness, and the compressive strengths of the UHPC and NC materials. Based on the ANN analyses, the explicit expression of UHPC–NC bond strength is proposed, which significantly lowers the prediction error. To be fully compatible with the specifications, the conventional shear-friction formula is modified. By splitting the total force into adhesion and friction forces, the modified formula additionally takes the casting sequence into account. Although sacrificing accuracy to some extent compared to the ANN model, the modified formula relies on a solid physical basis and its accuracy is enhanced significantly compared to the existing formulas in specifications or research papers.

scholarly journals SHEAR BOND STRENGTH OF CFRP DIRECTLY MOLDED ONTO STEEL SURFACE BY VaRTM TECHNOLOGY

2019 ◽  
Vol 25 (59) ◽  
pp. 189-192
Author(s):  
Genki MIEDA ◽  
Yukihiro MATSUMOTO ◽  
Takahiro MATSUI ◽  
Hitoshi NAKAMURA
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Steel Surface

Heterogeneous FE model for single lap shear tests on FRP reinforced masonry curved pillars with spike anchors

2020 ◽  
Vol 258 ◽  
pp. 119629 ◽  
Author(s):  
Elisa Bertolesi ◽  
Gabriele Milani ◽  
Mario Fagone ◽  
Tommaso Rotunno ◽  
Ernesto Grande
Keyword(s):  
Fe Model ◽  
Shear Tests ◽  
Lap Shear ◽  
Reinforced Masonry

Retrofitting Bond of Damaged Concrete Surface in Harbour Structures

2013 ◽  
Vol 684 ◽  
pp. 177-181
Author(s):  
Alireza Ghaffari ◽  
Amirreza Ghaffari
Keyword(s):  
Bond Strength ◽  
Silica Fume ◽  
Coarse Aggregate ◽  
Sea Water ◽  
Concrete Surface ◽  
Fine Aggregate ◽  
Water Pool ◽  
Repair Materials ◽  
Steel Bars ◽  
Slant Shear

An experimental research of the bonds amongst retrofitted materials on concrete structures under seashore climate has conducted. The strength of a bond between repair materials and concrete substratum has been assessed on the base of slant shear test experiment. In this research 52 samples has prepared and used for experiment .The fresh concrete with fine aggregate mix only (less than 9mm particle size without coarse aggregate) and 14% silica fume by weight of cement (normally 8 to 10% but 14% because of high amount of fine aggregate ) added to the mix which improve the properties of concrete such as bond strength as well as compressive strength and reduces permeability of sea water in corrosion or deterioration of steel bars by protecting reinforcing steel from erosion (pivotal aim of research) and even reduces abrasion resistance .Therefore silica fume was rolled an essential repairer materials on seashore structures. The retrofitted specimens were cured on water pool and kept on the seashore simulation climate upto required curing times . The strength of the improved samples has studied in three aspects as bond strength according surface roughness ,curing periods and concrete additives like silica fumes and fibres .

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