Research on Evaluation Method of Ultrasonic Testing for Inspection of Concrete Jointing Surface Quality

2014 ◽  
Vol 501-504 ◽  
pp. 877-880
Author(s):  
Lin Liu ◽  
Qiang Wang ◽  
Kai Guo
Keyword(s):  
Evaluation Method ◽  
Weak Link ◽  
Ultrasonic Method ◽  
Critical Value ◽  
Angle Measurement ◽  
Joint Surface ◽  
Probability Method ◽  
Near Surface ◽  
Core Drilling ◽  
Value Determination

The combining Part Of new-old concrete is a weak link. The cohesive strength of the combining layer is generally lower than the strength of the concrete poured completely. It will greatly affect the reliability of structure, when the combining layer is bad. It is a effective method to Inspect combining surface conditions by ultrasonic method. But related specification for defect judgment method of ultrasonic method, which is not fit to detect the defect area is larger in detect area, the overall quality of members is poor, make the discreteness of data less, those causes low judgment value, and the defects to leakage. In addition, the less data is not easy to found out the outliers. We adopted ultrasonic angle measurement method for concrete jointing surface of 50 pillars testing analysis, Method to determine the critical value of defect of abnormal value, and studied critical value determination method of defects outliers, propose a method of defects determination base on the common probability method. As detection is shown, first, with this method detect the joint surface of the concrete columns, contrasted core drilling results, prove the method is effective and feasible. Second, For new pouring concrete quality is poorer near surface, defect points too much, contrasted core drilling results, prove the method is effective and feasible. In addition, using this method for detecting data less, contrasted core drilling results, prove the method is effective and feasible.

scholarly journals Evaluation of Damage Process of a Coating by Using Nonlinear Ultrasonic Method

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 440
Author(s):  
Chunguang Xu ◽  
Lei He ◽  
Shiyuan Zhou ◽  
Dingguo Xiao ◽  
Pengzhi Ma
Keyword(s):  
Tensile Stress ◽  
Order Parameter ◽  
Evaluation Method ◽  
Early Stage ◽  
Ultrasonic Method ◽  
Nonlinear Coefficient ◽  
Damage Index ◽  
Second Order ◽  
External Loading ◽  
Nonlinear Ultrasonic

During the service or external loading of the surface coating, the damage accumulation may develop in the coating or at the interface between the substrate and the coating, but it is difficult to measure directly in the early stage, so the acoustic nonlinear parameters are used as the early damage index of the coating. In this paper, the nonlinear wave motion equation is solved by the perturbation method and the new relationship between the relative ratio of second-order parameter and third-order parameter was derived. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing of for the specimen with Al2O3 coatings. It is found that when the stress is less than 260 MPa, the appearance of the coating has no obvious change, but the nonlinear coefficients measured by the experiment increase with the increase of the tensile stress. By comparing the curves of nonlinear coefficients and stress respectively, the fluctuation of curves the second-order nonlinear coefficient A2 and the relative nonlinear coefficient β′ to stress is relatively small, and close to the linear relationship with the tensile stress, which indicates that the two parameters of the specimen with Al2O3 coatings are more sensitive to the bonding conditions, and can be used as an evaluation method to track the coating damage.

scholarly journals MULTI-WAVE ULTRASONIC CONTROL OF CONCRETE

2017 ◽  
Vol 16 (4) ◽  
pp. 289-297
Author(s):  
D. Yu. Snezgkov ◽  
S. N. Leonovich
Keyword(s):  
Rayleigh Wave ◽  
Pulse Propagation ◽  
Ultrasonic Method ◽  
Physical And Mechanical Properties ◽  
Pulse Velocity ◽  
Energy Localization ◽  
Near Surface ◽  
In Situ Conditions ◽  
Selection Of

The existing non-destructive testing system of structure concrete is actually orientated on the usage of longitudinal acoustical waves. This is due to simplicity of technical realization for measuring velocity (time) of acoustical pulse propagation in bulk concrete. But a reverse side of simple measuring procedure is a loss of additional information on concrete which is contained in the accepted acoustical signal. Therefore usage of an ultrasonic concrete testing method is limited by assessment of its strength. Joint usage of several wave types, so-called multi-wave testing, allows to refine metrology parameters of the ultrasonic method and to gain more information while determining physical and mechanical properties of concrete in laboratory and in situ conditions. The paper considers testing of elongated concrete elements and structures by an ultrasonic pulsing method on the basis of longitudinal subsurface and Rayleigh waves. It has been proposed to use methodology for time selection of wave components according to amplitude parameter and it has been applied for standard acoustical transformers with considerable reverberation time and not possessing spatial selectivity Basic principle of the proposed methodology is visual (according to oscillogram of the received signal) determination of characteristic time moments which are used for calculation of differential value of a propagation velocity in the Rayleigh wave impulse. The paper presents results pertaining to simulation of acoustical pulse propagation on the basis of 0.15 m and data of concrete ultrasonic in situ testing on measuring bases from 0.25 to 1.75 m. Advantage of large baseline for sonic test is a possibility for execution of a hundred percent inspection for surface of large-sized elements and structures, and so there is no need to make a selective inspection in some control areas as it is stipulated by provided by existing regulations. Responsivity of the Rayleigh wave parameters to near surface concrete defects permits quickly and efficiently to detect crack areas in a reinforced structure. Energy localization of a surface wave in a layer having width λ/2–λ provides a possibility to ignore reinforcement availability under appropriate selection of oscillation frequency. In addition to this, large measuring baseline makes it possible to lower effect of concrete structural inhomogeneity on statistical stability for pulse velocity assessment that ultimately reveals a possibility to register an appearance of concrete acoustical elasticity effect under in situ conditions.

scholarly journals Intragranular Residual Stress Evaluation Using the Semi-Destructive FIB-DIC Ring-Core Drilling Method

2014 ◽  
Vol 996 ◽  
pp. 8-13 ◽  
Author(s):  
Alexander J.G. Lunt ◽  
Alexander M. Korsunsky
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Titanium Aluminide ◽  
Ion Beam ◽  
Sample Surface ◽  
Image Correlation ◽  
Near Surface ◽  
Core Drilling ◽  
Drilling Method ◽  
Ring Core

Titanium aluminide (TiAl) is a lightweight intermetallic compound with a range of exceptional mid-to-high temperature mechanical properties. These characteristics have the potential to deliver significant weight savings in aero engine components. However, the relatively low ductility of TiAl requires improved understanding of the relationship between manufacturing processes and residual stresses in order to expand the use of such components in service. Previous studies have suggested that stress determination at high spatial resolution is necessary to achieve better insight. The present paper reports progress beyond the current state-of-the-art towards the identification of the near-surface intragranular residual stress state in cast and ground TiAl at a resolution better than 5μm. The semi-destructive ring-core drilling method using Focused Ion Beam (FIB) and Digital Image Correlation (DIC) was used for in-plane residual stress estimation in ten grains at the sample surface. The nature of the locally observed strain reliefs suggests that tensile residual stresses may have been induced in some grains by the unidirectional grinding process applied to the surface.

Climatological study of the Boundary-layer air Stagnation Index for China and its relationship with air pollution

2020 ◽  
Author(s):  
Qianqian Huang ◽  
Xuhui Cai ◽  
Jian Wang ◽  
Yu Song ◽  
Tong Zhu
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Weak Link ◽  
Fine Particulate Matter ◽  
Pollution Index ◽  
Climatic Data ◽  
Near Surface ◽  
National Climatic Data Center ◽  
The Us ◽  
Pm2.5 Concentration

<p>The Air Stagnation Index (ASI) is a vital meteorological measure of the atmosphere’s ability to dilute air pollutants. The original metric adopted by the US National Climatic Data Center (NCDC) is found to be not very suitable for China, because the decoupling between the upper and lower atmospheric layers results in a weak link between the near-surface air pollution and upper-air wind speed. Therefore, a new threshold for the ASI–Boundary-layer air Stagnation Index (BSI) is proposed, consisting of daily maximal ventilation in the atmospheric boundary layer, precipitation, and real latent instability. In the present study, the climatological features of the BSI are investigated. It shows that the spatial distribution of the BSI is similar to the ASI; that is, annual mean stagnations occur most often in the northwestern and southwestern basins, i.e., the Xinjiang and Sichuan basins (more than 180 days), and least over plateaus, i.e., the Qinghai–Tibet and Yunnan plateaus (less than 40 days). However, the seasonal cycle of the BSI is changed. Stagnation days under the new metric are observed to be maximal in winter and minimal in summer, which is positively correlated with the air pollution index (API) during 2000–2012. The correlations between the BSI and the concentration of fine particulate matter (PM2.5) during January 2013 and November to December in 2015–2017 of Beijing are also investigated. It shows that the BSI matches the day-by-day variation of PM2.5 concentration very well and is able to catch the haze episodes.</p>

Metro Operation Safety Evaluation

2014 ◽  
Vol 505-506 ◽  
pp. 467-470
Author(s):  
Li Yun Wei ◽  
Yong Bo Lv ◽  
Yuan Ren
Keyword(s):  
Traffic Safety ◽  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Weak Link ◽  
Management Strategies ◽  
Safety Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Comprehensive Evaluation Method ◽  
Urban Rail

In order to evaluate urban rail traffic safety performance comprehensively and to find the weak link to strengthen management, this article, it used the secondary fuzzy comprehensive evaluation method for safety assessment. the qualitative analysis was done to emphasis the structure importance and management strategies are put forward based on the results.

scholarly journals Critical value determination on similarity of fingerprints

2006 ◽  
Vol 82 (1-2) ◽  
pp. 236-240 ◽  
Author(s):  
Kai-Tai Fang ◽  
Yi-Zeng Liang ◽  
Xiao-lin Yin ◽  
Kelvin Chan ◽  
Guang-Hua Lu
Keyword(s):  
Critical Value ◽  
Value Determination

Dynamic Characteristic Analysis and Structural Modification of a 5-Axis Horizontal Machining Center Considering Joint Surface

2011 ◽  
Vol 697-698 ◽  
pp. 513-516
Author(s):  
Y.G. Shi ◽  
Xing Yu Zhao ◽  
Li Qiang Zeng ◽  
H.Y. Wang ◽  
Da Wei Zhang
Keyword(s):  
Finite Element ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Structural Modification ◽  
Weak Link ◽  
Joint Surface ◽  
Element Calculation ◽  
Characteristic Analysis ◽  
Machining Center ◽  
Surface Dynamic

In order to make a 5-axis linkage horizontal machining center have better dynamic characteristics, considering the influence of joint surface, dynamic characteristic analysis is conducted to the machining tool. Based on finite element modal analysis results, the weak link is found and optimized. Through the finite element calculation and analysis, the structure rigidity obviously raises after optimization. This offers a new idea on how to improve the rigidity of complete machine of machining tool for later research.

scholarly journals Borehole temperatures at the Colle Gnifetti core-drilling site (Monte Rosa, Swiss Alps)

1991 ◽  
Vol 37 (125) ◽  
pp. 37-46 ◽  
Author(s):  
Wilfried Haeberli ◽  
Martin Funk
Keyword(s):  
Heat Flow ◽  
20Th Century ◽  
Swiss Alps ◽  
Model Calculations ◽  
Near Surface ◽  
Core Drilling ◽  
Air Temperatures ◽  
Dependent Model ◽  
Drilling Site ◽  
Monte Rosa

Abstract Measured englacial temperatures at the Colle Gnifetti core-drilling site are presented and compared with model calculations concerning possible effects of 20th century warming. The firn/ice saddle at the 124 m deep saddle borehole is cold throughout with a mean annual surface temperature near –14°C and a basal temperature slightly below –12°C. Influence of refreezing meltwater is weak and limited to near-surface formation of ice layers (recrystallization-infiltration). Temperature gradients in the saddle borehole are positive and increase from 0.015° to 0.019°C m−1 between 30 m depth and bedrock, corresponding to a mean vertical heat flow of around 50mWm−2. The observed temperature profile is close to steady-state conditions. It can well be reproduced with time-dependent model calculations using mean annual air temperatures from the nearby weather station of Grand St. Bernard within the main chain of the Swiss Alps, but it significantly deviates from similar calculations based on Säntis data, reflecting developments of air temperatures on the northern slope of the Alps. 20th century warming of cold Alpine firn seems to be much less pronounced than in polar areas, where strong heat-flow anomalies are commonly observed.

Thermal error controlling for the spindle in a precision boring machine with external cooling across coated joints

2019 ◽  
Vol 234 (2) ◽  
pp. 658-675
Author(s):  
Mohan Lei ◽  
Gedong Jiang ◽  
Liang Zhao ◽  
Jinshi Wang ◽  
Ben Q Li ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Thermal Equilibrium ◽  
Evaluation Method ◽  
Control Method ◽  
Thermal Error ◽  
Joint Surface ◽  
Internal Cooling ◽  
Equilibrium Time ◽  
External Cooling ◽  
Boring Machines

Spindles in precision boring machines usually operate without internal cooling, and thermal error in such spindles is nonnegligible and can severely affect the end-processing quality of the machines. This study aims to investigate the effects that external cooling exerts on the thermal behavior of such spindles. A helical tube cooler is taken for external cooling. An analytical thermal resistance model for the grease-coated cooler-housing joint surface, which considers the pressured cambered-flat contact pair and rough metal surface-grease contact, is presented and validated, and a numerical thermal–fluid–solid coupling model for the cooler-spindle system is then established. An evaluation method is put forward to obtain the stability of the thermal error, which determines the boring processing accuracy and thermal equilibrium time, from experimental data. Then, the external cooling was optimally designed based on the simulation results from the numerical model. Experiments show that the designed cooler reduced the thermal equilibrium time by 47.13% and the maximum thermal error by 81.7%, and the proposed model can accurately predict the cooling effect on the spindle thermal behavior. This study not only provides a thermal error control method for the spindle but is expected to advance the theoretical basis of cooling design for complex electromechanical systems.

Rule-of-Thumb Formulas for Extending the Versatility of Tidal Current Tables

2000 ◽  
Vol 34 (2) ◽  
pp. 18-21
Author(s):  
Ben J. Korgen
Keyword(s):  
Tidal Current ◽  
Critical Value ◽  
Tidal Currents ◽  
Current Speed ◽  
Time Interval ◽  
Local Conditions ◽  
Near Surface ◽  
Rule Of Thumb ◽  
Safety Margins ◽  
Scientific Results

Four rule-of-thumb formulas have been derived for use in conjunction with existing tidal current tables. For near-surface tidal currents, these formulas yield 1) the percent of time current speed is above a critical value, 2) the percent of time current speed is below a critical value, 3) the time interval when current speed is above a critical value, and 4) the time interval when current speed is below a critical value. The formulas presented require as inputs the near-surface tidal current speed predictions found in standard tidal current tables. Intended for making rough approximations, these formulas may be useful in planning operations for which information on near-surface tidal currents is important. They are not scientific results or predictive models on which anyone’s life should depend. They should be used only with generous safety margins and if possible, with in situ current measurements, since local conditions may vary considerably.

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