Folding stress analysis of a sandwich plate based on transversely isotropic and rate-dependent constitutive relationship of adhesive

2021 ◽  
pp. 1-30
Author(s):  
Xiangzhe Li ◽  
Wenyu Li ◽  
Ri Xia ◽  
Mingchen Huo ◽  
Jinquan Xu
Keyword(s):  
Stress Analysis ◽  
Sandwich Plate ◽  
Transversely Isotropic ◽  
Constitutive Relationship ◽  
Rate Dependent ◽  
Relationship Of

The MHD Flows for a Heated Generalized Oldroyd-B Fluid With Fractional Derivative

2010 ◽  
Author(s):  
Yaqing Liu ◽  
Liancun Zheng ◽  
Xinxin Zhang ◽  
Fenglei Zong
Keyword(s):  
Fractional Calculus ◽  
Viscoelastic Fluid ◽  
Mhd Flow ◽  
Hankel Transform ◽  
Constitutive Relationship ◽  
Temperature Fields ◽  
Fractional Partial Differential Equations ◽  
Relation Model ◽  
Velocity And Temperature Fields ◽  
Relationship Of

In this paper, we present a circular motion of magnetohydrodynamic (MHD) flow for a heated generalized Oldroyd-B fluid. The fractional calculus approach is introduced to establish the constitutive relationship of a viscoelastic fluid. The velocity and temperature fields of the flow are described by fractional partial differential equations. Exact analytical solutions of velocity and temperature fields are obtained by using Hankel transform and Laplace transform for fractional calculus. Results for ordinary viscous flow are deduced by making the fractional order of differential tend to one and zero. It is shown that the fractional constitutive relation model is more useful than the conventional model for describing the properties of viscoelastic fluid.

scholarly journals Simulating the Stress-Strain Relationship of Geomaterials by Support Vector Machine

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hongbo Zhao ◽  
Zenghui Huang ◽  
Zhengsheng Zou
Keyword(s):  
Support Vector Machine ◽  
Constitutive Relationship ◽  
Support Vector ◽  
Nonlinear Relationship ◽  
Ann Model ◽  
Stress Strain ◽  
Svm Model ◽  
Strain Relationship ◽  
Artificial Neural Network Ann ◽  
Relationship Of

Stress-strain relationship of geomaterials is important to numerical analysis in geotechnical engineering. It is difficult to be represented by conventional constitutive model accurately. Artificial neural network (ANN) has been proposed as a more effective approach to represent this complex and nonlinear relationship, but ANN itself still has some limitations that restrict the applicability of the method. In this paper, an alternative method, support vector machine (SVM), is proposed to simulate this type of complex constitutive relationship. The SVM model can overcome the limitations of ANN model while still processing the advantages over the traditional model. The application examples show that it is an effective and accurate modeling approach for stress-strain relationship representation for geomaterials.

scholarly journals Structural Safety Evaluation of Tunnel Based on the Dynamic Monitoring Data during Construction

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaokun Yan ◽  
Hu Li ◽  
Feng Liu ◽  
Yang Liu
Keyword(s):  
Safety Evaluation ◽  
Constitutive Relationship ◽  
Monitoring Data ◽  
Dynamic Monitoring ◽  
Structural Safety ◽  
Underground Excavation ◽  
Tunnel Excavation ◽  
Evaluation Approach ◽  
Relationship Of ◽  
Shallow Buried Tunnel

It is still a challenge to accurately evaluate the structural safety of tunnel during the process of construction. To address this issue, a safety evaluation approach of tunnel based on the monitoring data during construction is proposed in this study. Firstly, the detailed description of modelling the tunnel excavation, releasing the load acting on the tunnel, and selecting the constitutive relationship of surrounding rock of tunnel is introduced. Secondly, aiming at an actual shallow-buried tunnel with underground excavation, utilizing the analytical results of deformation of tunnel, the structural safety of tunnel is evaluated by using a reliability-based method. Finally, the effectiveness of the proposed method is demonstrated by using the dynamic monitoring data obtained during the construction of an actual tunnel.

scholarly journals Heart Rate Dependency and Inter-Lead Variability of the T Peak – T End Intervals

2020 ◽  
Vol 11 ◽  
Author(s):  
Irena Andršová ◽  
Katerina Hnatkova ◽  
Martina Šišáková ◽  
Ondřej Toman ◽  
Peter Smetana ◽  
...  
Keyword(s):  
Heart Rate ◽  
Three Dimensional ◽  
Rate Dependency ◽  
Rate Dependent ◽  
Heart Rate Correction ◽  
Ecg Leads ◽  
Relationship Of ◽  
The Relationship ◽  
Vector Magnitude

The electrocardiographic (ECG) assessment of the T peak–T end (Tpe) intervals has been used in many clinical studies, but several related physiological aspects have not been reported. Specifically, the sources of the Tpe differences between different ECG leads have not been systematically researched, the relationship of Tpe duration to underlying heart rate has not been firmly established, and little is known about the mutual correspondence of Tpe intervals measured in different ECG leads. This study evaluated 796,620 10-s 12-lead ECGs obtained from long-term Holters recorded in 639 healthy subjects (311 female) aged 33.8 ± 9.4 years. For each ECG, transformation to orthogonal XYZ lead was used to measure Tpe in the orthogonal vector magnitude (used as a reference for lead-to-lead comparisons) and to construct a three-dimensional T wave loop. The loop roundness was expressed by a ratio between its circumference and length. These ratios were significantly related to the standard deviation of Tpe durations in different ECG leads. At the underlying heart rate of 60 beats per minute, Tpe intervals were shorter in female than in male individuals (82.5 ± 5.6 vs 90.0 ± 6.5 ms, p < 0.0001). When studying linear slopes between Tpe intervals measured in different leads and the underlying heart rate, we found only minimal heart rate dependency, which was not systematic across the ECG leads and/or across the population. For any ECG lead, positive Tpe/RR slope was found in some subjects (e.g., 79 and 25% of subjects for V2 and V4 measurements, respectively) and a negative Tpe/RR slope in other subjects (e.g., 40 and 65% for V6 and V5, respectively). The steepest positive and negative Tpe/RR slopes were found for measurements in lead V2 and V4, respectively. In all leads, the Tpe/RR slope values were close to zero, indicating, on average, Tpe changes well below 2 ms for RR interval changes of 100 ms. On average, longest Tpe intervals were measured in lead V2, the shortest in lead III. The study concludes that the Tpe intervals measured in different leads cannot be combined. Irrespective of the measured ECG lead, the Tpe interval is not systematically heart rate dependent, and no heart rate correction should be used in clinical Tpe investigations.

scholarly journals Compressive Test Characteristics and Constitutive Relationship of Wet Polypropylene Macrofiber-Reinforced Shotcrete

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Fenghui Li ◽  
Yunhai Cheng ◽  
Fei Wu ◽  
Chang Su ◽  
Gangwei Li
Keyword(s):  
Mechanical Response ◽  
Average Energy ◽  
Strain Curve ◽  
Peak Stress ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Response Characteristics ◽  
Test Characteristics ◽  
High Crack ◽  
Relationship Of

Shotcrete is often subject to poor ductility and cracking problems, particularly under high stresses. In order to deal with these issues, the feasibility of adding polypropylene macrofibers to shotcrete was verified. To ascertain the supporting effect, dry shotcrete, wet shotcrete, and wet polypropylene macrofiber-reinforced shotcrete (WPMS) were used as samples. Furthermore, the mechanical response characteristics thereof in uniaxial compression tests were compared and analyzed by acoustic emission (AE) monitoring. The results showed that the three materials were brittle, but the ductility, residual strength, and bearing capacity of polypropylene macrofiber-reinforced shotcrete were significantly enhanced. The energy absorption value of plain shotcrete was higher in the cracking stage, while that of polypropylene macrofiber-reinforced shotcrete was greater in the postpeak stage, which showed that the polypropylene macrofiber-reinforced shotcrete had the characteristics of a high crack-initiation strength and toughness. Besides, the energy release from fiber shotcrete occurred after the peak stress rather than near the peak stress. The average energy absorbed by polypropylene macrofiber-reinforced shotcrete was significantly higher than that in dry shotcrete and wet shotcrete, which implied that polypropylene macrofiber-reinforced shotcrete could mitigate the brittle instability of a shotcrete layer. A constitutive model of damage statistics was established based on the test data. The comparison between the experimental data and the fitting results can reflect the characteristics of the total stress-strain curve of such shotcrete. The results provide a basis for the optimization of polypropylene macrofiber-reinforced shotcrete layers.

scholarly journals Failure Criteria and Constitutive Relationship of Lightweight Aggregate Concrete under Triaxial Compression

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 507
Author(s):  
Peihuan Ye ◽  
Yuliang Chen ◽  
Zongping Chen ◽  
Jinjun Xu ◽  
Huiqin Wu
Keyword(s):  
Triaxial Compression ◽  
Lightweight Aggregate ◽  
Confining Pressure ◽  
Failure Criteria ◽  
Constitutive Relationship ◽  
Lightweight Aggregate Concrete ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Stress Theory ◽  
Relationship Of

This paper investigates the compression behavior and failure criteria of lightweight aggregate concrete (LAC) under triaxial loading. A total of 156 specimens were tested for three parameters: concrete strength, lateral confining pressure and aggregate immersion time, and their effects on the failure mode of LAC and the triaxial stress-strain relationship of LAC is studied. The research indicated that, as the lateral constraint of the specimen increases, the failure patterns change from vertical splitting failure to oblique shearing failure and then to indistinct traces of damage. The stress-strain curve of LAC specimens has an obvious stress plateau, and the curve no longer appears downward when the confining pressure exceeds 12 MPa. According to the experimental phenomenon and test data, the failure criterion was examined on the Mohr–Coulomb theory, octahedral shear stress theory and Rendulic plane stress theory, which well reflects the behavior of LAC under triaxial compression. For the convenience of analysis and application, the stress-strain constitutive models of LAC under triaxial compression are recommended, and these models correlate well with the test results.

scholarly journals Inelastic Constitutive Relationship of Electroplated Nickel Films at Elevated Temperatures for Design of Micro Connector

2005 ◽  
Vol 125 (7) ◽  
pp. 294-301
Author(s):  
Yoshitada Isono ◽  
Junichi Tada ◽  
Toshinori Unno ◽  
Susumu Sugiyama ◽  
Toshiyuki Toriyama
Keyword(s):  
Elevated Temperatures ◽  
Constitutive Relationship ◽  
Nickel Films ◽  
Relationship Of
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