Improved Load Ratio Method for Predicting Crack Length

2009 ◽  
pp. 83-83-21 ◽  
Author(s):  
X Chen ◽  
P Albrecht ◽  
W Wright ◽  
JA Joyce
Keyword(s):  
Crack Length ◽  
Load Ratio ◽  
Ratio Method

Calculation of the Crack Length for a Pipe Specimen using the Modified Load Ratio Method

2009 ◽  
Vol 33 (12) ◽  
pp. 1375-1382
Author(s):  
Jung-Hun Choi ◽  
Yong Huh ◽  
Jae-Mean Koo ◽  
Chang-Sung Seok ◽  
Jae-Sil Park
Keyword(s):  
Crack Length ◽  
Load Ratio ◽  
Ratio Method

scholarly journals Passive Cooling Load Ratio method

2013 ◽  
Vol 64 ◽  
pp. 209-217 ◽  
Author(s):  
Ana I.F. Nunes ◽  
Marta J.N. Oliveira Panão
Keyword(s):  
Load Ratio ◽  
Ratio Method ◽  
Passive Cooling ◽  
Cooling Load

An Efficient Way to Characterize the Fatigue Crack Growth Based on Numerical Analysis

2009 ◽  
Vol 417-418 ◽  
pp. 653-656
Author(s):  
Ya Zhi Li ◽  
Jing He ◽  
Zi Peng Zhang
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Length ◽  
Crack Growth ◽  
Crack Closure ◽  
Load Ratio ◽  
Specimen Thickness

The behavior of plasticity induced fatigue crack closure (PICC) in middle tension specimen was analyzed by the elastic-plastic finite element method. For the constant-K (CK) loading cases, the opening stress intensity factor are independent of crack length. The level of increases with the maximal applied stress intensity factor for given load ratio and increases with for fixed . The in plane strain state is much smaller than that in plane stress state. The results under CK loadings can be deduced to constant amplitude cyclic loading case during which the load ratio, maximal load level, crack length and specimen thickness are all the factors affecting the crack closure effect. The phenomena revealed in the analysis are beneficial in understanding the driving force mechanism of the fatigue crack growth.

scholarly journals Fracture Formation Evaluation of Reinforced Concrete Structure Using Acoustic Emission Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Alireza Panjsetooni ◽  
Norazura Muhamad Bunnori ◽  
Amir Hossein Vakili ◽  
Zohreh Shirkhani ◽  
Zeinab Shirkhani
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Concrete Structure ◽  
Structural Engineering ◽  
Load Ratio ◽  
Ratio Method ◽  
Reinforced Concrete Structure ◽  
Remaining Service Life ◽  
Fracture Formation ◽  
Viable Method

Acoustic emission (AE) is an important nondestructive evaluation (NDE) technique used in the field of structural engineering for both case local and global monitoring. In this study AE technique with a new approach was employed to investigate the process of fracture formation in reinforced concrete structure. A number of reinforced concrete (RC) one story frames were tested under loading cycle and were simultaneously monitored using AE. The AE test data was analyzed using the relaxation ratio and calm and load ratio method. Also, the relaxation ratio was dominated with approaching load to 58% of the ultimate load. In addition three levels of damage using calm and load ratio were distinguished. The trend of relaxation ratio and calm and load ratio method during loading and unloading showed that these methods are strongly sensitive with cracks growth in RC frame specimens and were able to indicate the levels of damage. Also, results showed that AE can be considered as a viable method to predict the remaining service life of reinforced concrete. In addition, with respect to the results obtained from relaxation ratio and, load and calm ratio indicated, a new chart is proposed.

scholarly journals A Calibration of the Solar Load Ratio Method to Determine the Heat Gain in PV-Trombe Walls

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 328
Author(s):  
Roberto Bruno ◽  
Piero Bevilacqua ◽  
Daniela Cirone ◽  
Stefania Perrella ◽  
Antonino Rollo
Keyword(s):  
Dimensionless Parameter ◽  
Load Ratio ◽  
Empirical Method ◽  
Ratio Method ◽  
Passive System ◽  
Actual Performance ◽  
Simulation Tools ◽  
Trombe Wall ◽  
Visual Impact ◽  
Energy Gains

The Trombe wall is a passive system used in buildings that indirectly transfers thermal energy to the adjacent environment by radiation and convection, and directly by the thermo-circulation that arises in the air cavity delimited between a transparent and an absorbing surface. Nevertheless, the latter is painted black to increase the energy gains, but this produces a negative visual impact and promotes the overheating risk in summer. To mitigate these aspects, a hybrid Trombe wall equipped with PV panels can be employed. The PV installation results in a more pleasing wall appearance and the overheating risk reduces because part of the absorbed solar radiation is transformed into electricity. To determine the actual performance of a such system, transient simulation tools are required to consider properly the wall thermal storage features, variation of the optical properties, air thermo-circulation, and PV power production. Alternatively, regarding the traditional Trombe wall, the literature provides a simplified empirical method based on the dimensionless parameter solar load ratio (SLR) that allows for preliminary evaluations and design. In this paper, the SLR method was calibrated to determine the monthly auxiliary energy to be supplied in buildings equipped with PV-Trombe walls in heating applications. The SLR method was tuned by a multiple linear regression by data provided by TRNSYS simulation that allowed to obtain the energy performances in actual conditions of PV-Trombe walls installed on the same building but located in different localities. The comparison between the TRNSYS results and the calibrated SLR method determined average errors ranging between 0.7% and 1.4%, demonstrating the validity of the proposed methodology.

Experimental investigation and theoretical analysis of tear propagation of GQ-6 airship envelope

2016 ◽  
Vol 48 (1) ◽  
pp. 304-321 ◽  
Author(s):  
Fengxin Wang ◽  
Yonglin Chen ◽  
Guangzhong Liu ◽  
Zhengming Guo ◽  
Gongyi Fu
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Theoretical Analysis ◽  
Crack Length ◽  
Load Ratio ◽  
Initial Crack ◽  
Experimental Results ◽  
Crack Orientation ◽  
Initial Crack Length ◽  
Critical Energy Release Rate

This paper reports the central tearing properties of a new airship envelope fabric, GQ-6, from experimental investigation and theoretical analysis. First, the effects of the load ratio, the initial crack length, and the crack orientation on the tearing mechanical properties of such material were evaluated. The experimental results revealed that the mechanical properties of GQ-6 decrease with the increase of initial crack length. Two fracture modes were observed, e.g. either along the warp or the weft yarns directions, which depend on crack orientation and load ratio. Oriented crack can be represented by non-oriented crack with crack equivalent length under biaxial condition. The toughness KIC for the fabric was determined based on experimental results, as well as critical energy release rate GIC. A comparison of the mechanical behaviors of this textile under uniaxial and biaxial tensile condition is also presented. The allowable crack length for GQ-6 envelope fabric during working condition is estimated.

The Effects of Loading Frequency, Sensitization, and Crack Length on Corrosion Fatigue of AA5456-H116

CORROSION ◽  
10.5006/3366 ◽  
2019 ◽  
Vol 76 (1) ◽  
pp. 63-70 ◽  
Author(s):  
D.J. Schrock ◽  
J.S. (Warner) Locke
Keyword(s):  
Crack Length ◽  
Corrosion Fatigue ◽  
Load Ratio ◽  
Fatigue Loading ◽  
Loading Frequency ◽  
Corrosion Fatigue Crack ◽  
Full Immersion ◽  
Corrosion Fatigue Crack Growth ◽  
High Level ◽  
Crack Growth Rates

The effects of fatigue loading frequency (f), sensitization, and crack length on corrosion fatigue crack growth rates (da/dN) were investigated for AA5456-H116 under full immersion in 3.5 wt% NaCl. Results from fracture mechanics-based experiments conducted at a constant stress-intensity range (ΔK) and load ratio (R) suggest that highly sensitized AA5456-H116 microstructures (ASTM G67 nitric acid mass loss tests [NAMLT] value of 24 mg/cm2 and higher) exhibit increased da/dN over microstructures in the as-received condition (NAMLT 5 mg/cm2) and the onset of an inverse f-dependence. For a single, high level of sensitization (70 mg/cm2), da/dN increased 3.5× as f decreased from 10 Hz to 0.03 Hz. At a singular low loading f of 0.03 Hz, high sensitization levels (65 mg/cm2) accelerated da/dN fivefold over da/dN in the as-received condition. The da/dN of microstructures below a critical NAMLT value of 24 mg/cm2 were f-independent. Specifically, in microstructures with a low sensitization level (ASTM G67 NAMLT value less than 24 mg/cm2), there was no increase in da/dN as f decreased from 1 Hz to 0.03 Hz. At any singular f, sensitization up to 24 mg/cm2 did not accelerate da/dN over the rate in an as-received microstructure. Additional testing established that the inverse f-dependence of da/dN observed in highly sensitized microstructures cannot be attributed to crack length effects. Two hypotheses are discussed that may explain the observed inverse relationship between f and da/dN in microstructures at or above the critical NAMLT value of 24 mg/cm2.

X-Ray Analysis of Frozen Hydrated Sections:The Unconventional Approach

1982 ◽  
Vol 40 ◽  
pp. 754-757
Author(s):  
R. Beeuwkes ◽  
A. Saubermann ◽  
P. Echlin ◽  
S. Churchill
Keyword(s):  
Ratio Method ◽  
Frozen Sections ◽  
Technical Problems ◽  
Sample Handling ◽  
X Ray ◽  
Common Group ◽  
Ideal Method ◽  
Classic Paper ◽  
Physical Principles ◽  
The Ideal

Fifteen years ago, Hall described clearly the advantages of the thin section approach to biological x-ray microanalysis, and described clearly the ratio method for quantitive analysis in such preparations. In this now classic paper, he also made it clear that the ideal method of sample preparation would involve only freezing and sectioning at low temperature. Subsequently, Hall and his coworkers, as well as others, have applied themselves to the task of direct x-ray microanalysis of frozen sections. To achieve this goal, different methodological approachs have been developed as different groups sought solutions to a common group of technical problems. This report describes some of these problems and indicates the specific approaches and procedures developed by our group in order to overcome them. We acknowledge that the techniques evolved by our group are quite different from earlier approaches to cryomicrotomy and sample handling, hence the title of our paper. However, such departures from tradition have been based upon our attempt to apply basic physical principles to the processes involved. We feel we have demonstrated that such a break with tradition has valuable consequences.

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