Results of round-robin testing for determining the double-K fracture parameters for crack propagation in concrete: technical report of the RILEM TC265-TDK

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Shilang Xu ◽  
Qinghua Li ◽  
Yao Wu ◽  
Lixin Dong ◽  
Yao Lyu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Round Robin ◽  
Fracture Parameters ◽  
Technical Report

Influential factors for double-K fracture parameters analyzed by the round robin tests of RILEM TC265-TDK

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Shilang Xu ◽  
Qinghua Li ◽  
Yao Wu ◽  
Lixin Dong ◽  
Yao Lyu ◽  
...  
Keyword(s):  
Round Robin ◽  
Influential Factors ◽  
Fracture Parameters

Interfacial Fracture Characterization of Nano-Scale Thin Films Using Single-Strip Stress-Engineered Superlayer

2006 ◽  
Author(s):  
Jiantao Zheng ◽  
Suresh K. Sitaraman
Keyword(s):  
Thin Films ◽  
Crack Propagation ◽  
Interfacial Crack ◽  
Interfacial Fracture ◽  
Critical Energy ◽  
Test Method ◽  
Nano Scale ◽  
Available Energy ◽  
Fracture Parameters

Characterization of interfacial fracture parameters for nano-scale thin films continues to be challenging due to the difficulties associated with preparing samples, fixturing and loading the samples, and extracting and analyzing the experimental data. In this paper, we propose a stress-engineered superlayer test method that can be used to measure the interfacial fracture parameters of nano-scale (as well as micro-scale) thin films without the need for loading fixtures. The proposed test employs the residual stress in sputter-deposited metals to provide the energy for interfacial crack propagation. The innovative aspect of the test is the use of an etchable release layer that is deposited between the two interfacial materials of interest. The release layer is designed such that the available energy for interfacial crack propagation will continue to decrease as the crack propagates, and at the location where the crack ceases to propagate, the available energy for crack propagation will be the critical energy for crack propagation or the interfacial fracture toughness. The proposed test method has been successfully used to characterize Ti thin film on Si substrate.

scholarly journals RILEM Standard: testing methods for determination of the double-K criterion for crack propagation in concrete using wedge-splitting tests and three-point bending beam tests, recommendation of RILEM TC265-TDK

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Shilang Xu ◽  
Qinghua Li ◽  
Yao Wu ◽  
Lixin Dong ◽  
Yao Lyu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Unstable Fracture ◽  
Calculation Methods ◽  
Testing Methods ◽  
Three Point Bending ◽  
Standard Testing ◽  
Fracture Parameters ◽  
Splitting Test ◽  
Wedge Splitting

AbstractIn this recommendation, standard testing methods for determination of the double-K criterion for Mode I crack propagation in concrete using wedge-splitting tests and three-point bending beam tests are specified for the fracture parameters of the initial cracking toughness $$K_{Ic}^{ini}$$ K Ic ini and the unstable fracture toughness $$K_{Ic}^{un}$$ K Ic un . Along with the recommendation of the standard testing methods, the theoretical background of the double-K criterion, the calculation methods and the results of round-robin testing for determining the double-K fracture parameters are presented in technical reports [1, 2]. The recommendation of the standard testing methods includes geometry for specimens, fabrication of specimens, testing machine, load transmission system and supports, measuring instruments, determination of initial cracking load Pini, determination of measured maximum load Pmax and initial compliance ci, calculation methods for wedge-splitting test and three-point bending beam test, as well as the testing results and testing report forms. According to these methods, the measured fracture parameters of double-K criterion can be used to describe the onset of cracking, and the onset of unstable cracking or failure for predicting crack initiation, structure failure and crack stability in concrete structures.

Inverse Analysis to Estimate Critical Crack Propagation Parameters for Elastic-Plastic and Graded Materials

2004 ◽  
Vol 261-263 ◽  
pp. 117-122
Author(s):  
Toshio Nakamura ◽  
Zi Qiang Wang
Keyword(s):  
Crack Propagation ◽  
Inverse Analysis ◽  
Crack Opening ◽  
Reaction Force ◽  
Accurate Estimation ◽  
Crack Advance ◽  
Inhomogeneous Materials ◽  
Graded Materials ◽  
Elastic Plastic ◽  
Fracture Parameters

Accurate crack propagation simulation requires critical fracture parameters to be known a priori. For elastic-plastic materials, two fundamental parameters are the separation energy and the peak stress required to generate new crack surfaces. In general, both are difficult to quantify since direct determinations are not possible in experiments. For inhomogeneous materials, such as graded materials, determination is even more complex since these parameters vary spatially. In this paper, a novel method based on an inverse analysis technique is proposed to estimate the fracture parameters of elastic-plastic and graded media. The method utilizes the Kalman filter to process measured data and extract best estimates of the unknown parameters. The accuracy of the method is examined in a verification study where a dynamically propagating crack in double cantilever beam type specimen is modeled. In the study, time variation records of crack opening displacement, opening strain, crack advance distance, and load point reaction force are used as possible measurements. Despite large noises in data, the results confirm accurate estimation. The estimates improve when multiple measurements are supplied to the inverse technique.

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