To see the other types of publications on this topic, follow the link: Initial tangent modulus and pavement.
Journal articles on the topic 'Initial tangent modulus and pavement'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Initial tangent modulus and pavement.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Konrad, J. M. "The use of tangent stiffness to characterize the resilient response of unbound crushed aggregates." Canadian Geotechnical Journal 43, no. 11 (2006): 1117–30. http://dx.doi.org/10.1139/t06-079.
Full textAbstract:
Repeated-load triaxial tests were conducted on crushed granitic base-course material to study the resilient response under different stress paths and compaction states. It has been established that the resilient response of this prestrained unbound granular material is best defined in terms of tangent stiffness (Et) and vertical stress (σv). The data also revealed the existence of a threshold value of tangent stiffness that is essentially dependent on initial confining stress for a given compaction state. When the tangent modulus exceeds this threshold value, a unique relationship between tangent stiffness and vertical stress exists for mobilized shear resistance ratios less than 0.4. This Et–σv relationship is independent of stress path. A simple power law model can be used to predict the resilient response of unbound base-course material and an approximate value of resilient modulus for any desired stress path and initial stress condition. The use of the tangent stiffness – vertical stress model for pavement design appears to be very promising.Key words: granular, material, resilient modulus, triaxial, stress path.
2
Rahman, Md Mostaqur, Kazi Moinul Islam, and Sarah Gassman. "Estimation of Resilient Modulus for Coarse-Grained Subgrade Soils from Quick Shear Tests for Mechanistic-Empirical Pavement Designs." Designs 3, no. 4 (2019): 48. http://dx.doi.org/10.3390/designs3040048.
Full textAbstract:
The resilient modulus represents the subgrade soil stiffness, and it is considered one of the key material inputs in the Mechanistic Empirical Pavement Design Guide (MEPDG). The resilient modulus is typically estimated in the laboratory using a repeated load cyclic triaxial test, which is complex and time consuming to perform. Technical ability is also required to prepare the test specimens, particularly for coarse-grained soils. Therefore, there is a need to estimate the resilient modulus of coarse-grained soils from other simpler tests. In this study, correlations of resilient modulus with soil index properties and quick shear (QS) test results (quick shear strength, stress at 1% strain and tangent modulus) were developed for remolded coarse-grained soils, collected from different geographic regions in South Carolina. The developed models showed good correlations of resilient modulus to tangent modulus and soil index properties. The average tangent, modulus obtained from 30% and 50% of maximum stress of the QS tests, moisture content, optimum moisture content, dry unit weight, and maximum dry unit weight showed a statistically significant effect on estimating the resilient modulus for coarse-grained subgrade soils. The validation study confirms that the developed models can be used for predicting the resilient modulus for South Carolina coarse-grained soils.
3
Khegai, A. O., N. M. Kirilin, T. S. Khegai, and O. N. Khegai. "Experimental investigation of stress-strain properties of steel fiber reinforced concrete of the higher classes." Вестник гражданских инженеров 17, no. 6 (2020): 77–82. http://dx.doi.org/10.23968/1999-5571-2020-17-6-77-82.
Full textAbstract:
The tangent modulus of elasticity and deformation modulus are the most important characteristics of steel fiber reinforced concrete. The tangent modulus of elasticity corresponds to the initial loading stage, whereas in the operation stage and the fracture stage, there is a modulus of the material deformation, which is smaller, due to the formation of cracks in the element and non-linear behavior of the material. The paper presents experimental investigations of the tangent modulus of elasticity and the deformation modulus of fiber-reinforced concrete, class В60 at various percentages of fiber reinforcement. Existing approaches to determination of the tangent modulus of elasticity are considered. The results obtained are compared with those presented by other researchers. Analytical dependence is proposed for determination of deformation modulus depending on the percentage of fiber reinforcement.
4
Wang, Min, and Xiao Hong Bai. "Experimental Research on Compression Characteristics of Compacted Loess." Applied Mechanics and Materials 275-277 (January 2013): 387–90. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.387.
Full textAbstract:
A series of compression tests were conducted on the samples taken from compacted soil site in Lulling, in order to investigate the compressibility of compacted loess in different water content and different compaction energy. Through statistics analysis of the testing data, the stress-strain curve of compacted loess could be expressed with Hyperbolic form. And the relation between initial tangent modulus and water content change coefficient was founded by introducing the water content change coefficient. The result shows that at the same compaction energy, the initial tangent modulus decreases and the ultimate strain increases as water content increases; while at the same water content change coefficient, the initial tangent modulus increases and the ultimate strain decreases as compaction effort increases.
5
Li, Longbiao. "Effect of Stochastic Loading on Tensile Damage and Fracture of Fiber-Reinforced Ceramic-Matrix Composites." Materials 13, no. 11 (2020): 2469. http://dx.doi.org/10.3390/ma13112469.
Full textAbstract:
In this paper, the effect of stochastic loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated. A micromechanical constitutive model is developed considering multiple damage mechanisms under tensile loading. The relationship between stochastic stress, tangent modulus, interface debonding and fiber broken is established. The effects of the fiber volume, interface shear stress, interface debonding energy, saturation matrix crack spacing and fiber strength on tensile stress–strain curve, tangent modulus, interface debonding fraction and fiber broken fraction are analyzed. The experimental tensile damage and fracture of unidirectional and 2D SiC/SiC composites subjected to different stochastic loading stress are predicted. When fiber volume increases, the initial composite strain decreases, the initial tangent modulus increases, the transition stress for interface debonding decreases and the initial fiber broken fraction decreases. When fiber strength increases, the initial composite strain and fiber broken fraction decrease.
6
Huang, Hua, Min Huang, and Jiangshu Ding. "Calculation of Tangent Modulus of Soils under Different Stress Paths." Mathematical Problems in Engineering 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/1916761.
Full textAbstract:
During excavation of foundation pit, soils of different sites may undergo different unloading paths. This study focuses on the tangent modulus of soil under different stress paths and provides theoretical basis for the deformation calculation of soil. In this paper, conventional triaxial compression test and K0 consolidation unloading test were conducted with mucky soil and silty clay to obtain the deformation characteristics of soils under different stress paths. Experiment results show that the soil samples exhibit distinct stress-strain characteristics under different stress paths, but they all show nonlinearity. The initial tangent modulus increases as the consolidation confining pressure intensifies. Then, based on the test data, the power function relationship between initial tangent modulus and confining pressure under unloading was verified. Simultaneously, a hyperbola function to express stress-strain relation of soils under the K0 consolidation unloading condition was proposed and proved. Finally, the formulas of the tangent modulus under K0 consolidation unloading were established referring to the derivation of that in Duncan–Chang model. The theoretical calculation results agree well with the test results. It can expand the use of the Duncan–Chang model and improve its application to engineering practice.
7
Fu, Jun, Yu Qin, and Qing Jun Ding. "Research on Influence of Longitudinal Gradient to Rigid Base Composite Road of Cross River (Sea) Tunnel under Large Longitudinal Slope." Advanced Materials Research 189-193 (February 2011): 1621–24. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1621.
Full textAbstract:
The influences of longitudinal gradient on the large longitudinal slope rigid base composite road of cross river(sea) tunnel are concerned recently. Then the relationships between sheering stresses versus slope angle, load, pavement depth, interlayer touch condition and modulus are discussed separately by a three dimensional FEM model. Calculation and analysis showed: gradient had great influence on the surface tangent load and little influence on design deflection, the base and surface.The maximum tension and sheer on surface were increased with the gradient. On general, the gradient and surface tangent load should be considered in structure analysis for the large longitudinal slope road.
8
Liu, Yufeng, Longbiao Li, Zhongwei Zhang, and Xiang Xiong. "Monotonic and Cyclic Loading/Unloading Tensile Behavior of 3D Needle-Punched C/SiC Ceramic-Matrix Composites." Materials 14, no. 1 (2020): 57. http://dx.doi.org/10.3390/ma14010057.
Full textAbstract:
In this paper, monotonic and cyclic loading/unloading tensile behavior of four different 3D needle-punched C/SiC composites are investigated. Under tensile loading, multiple micro parameters of tensile tangent modulus, tensile strength, and fracture strain are used to characterize tensile damage and fracture behavior. Under cyclic loading/unloading, multiple damage micro parameters of unloading residual strain, tensile peak strain, hysteresis loops width, hysteresis loops area, unloading and reloading inverse tangent modulus (ITM) are used to describe the tensile damage evolution. After tensile fracture, fracture surfaces were observed under a scanning electron microscope (SEM). Damage of matrix cracking, interface debonding, fibers fracture and pullout in different plies is observed. Relationships between composite tensile mechanical behavior, damage parameters, and micro damage mechanisms are established. When the fiber volume fraction along the loading direction increases, the composite initial tangent modulus, tensile strength and fracture strain increase, and the unloading residual strain, peak strain, hysteresis width and hysteresis area decrease. For Types 1–4 3D needle-punched C/SiC composite, the fiber volume lies in the range of 25.6–32.8%, the composite initial tangent modulus was in the range of 161.4–220.4 GPa, the composite tensile strength was in the range of 64.4–112.3 MPa, and the composite fracture strain was in the range of 0.16–0.25%.
9
Konrad, J. M., та Ph D. Nguyen. "Implementation of the tangent modulus – vertical stress (Et–σv) model for flexible pavements analysis". Canadian Geotechnical Journal 43, № 11 (2006): 1131–43. http://dx.doi.org/10.1139/t06-060.
Full textAbstract:
A recently developed nonlinear elastic model of granular material, referred to as the tangent modulus – vertical stress (Et–σv) model, was implemented into a finite element numerical solver FlexPDE. The FlexPDE program was used to compare deflection predictions with actual plate-load test data from a site near Québec City. The proposed Et–σv model performed well and led to excellent predictions for load levels of 40, 50, and 70 kN. Comparison with predictions using the Uzan model suggests that constitutive models of granular materials are best expressed in terms of vertical stress rather than mean stress for the prediction of elastic pavement response for field conditions.Key words: granular material, resilient modulus, triaxial test, plate-loading test, finite element.
10
Li, Xiao Long, Xiao Nan Li, Yan Hui Zhong, and Fu Ming Wang. "Modulus Back Analysis of Pavement Structure Based on PSO." Applied Mechanics and Materials 178-181 (May 2012): 1222–25. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.1222.
Full textAbstract:
A method for modulus back analysis of pavement structure based on particle swarm optimization (PSO) is presented. The principle and implementation process of the method is detailed. Some theoretical and experimental data of pavement deflection are selected to test its performance. The contrastive analysis of the modulus inversion results of the proposed method and some representative pavement modulus back calculation softwares using the same deflection data is also performed. The results show that the presented method has relatively high identification accuracy and notably computational stability, which can effectively reduces the influence of initial tentative value on inversion results of pevement modulus.
11
WADA, Chiharu, and Tetsuo SHOJI. "Fracture Toughness and its Relation to Initial Tangent Modulus of Granitic Rock." Journal of the Society of Materials Science, Japan 35, no. 389 (1986): 145–51. http://dx.doi.org/10.2472/jsms.35.145.
Full text
12
Mahedi, Masrur, Sahadat Hossain, Mohammad Faysal, and Mohammad Sadik Khan. "Potential Applicability of Impact Echo Method on Pavement Base Materials as a Nondestructive Testing Technique." Transportation Research Record: Journal of the Transportation Research Board 2657, no. 1 (2017): 47–57. http://dx.doi.org/10.3141/2657-06.
Full textAbstract:
The use of both recycled asphalt pavement and recycled concrete aggregates is increasing considerably in pavement construction. These materials are relatively weak and have to be stabilized with cement or other stabilizers. However, because of product variability and lack of strength and stiffness, their applicability has to be evaluated extensively. Traditionally practiced methods of evaluation might be unreasonable in terms of time, cost, reliability, and applicability. Rapid nondestructive methods, such as the spectral analysis of surface wave, impact echo, pulse velocity, and so forth, have the potential to be inexpensive and less time-consuming, as well as offering low variability of the test results. The objective of the study was to assess the potential applicability of the impact echo method in evaluating recycled pavement base materials. Six combinations (0%–100%, 10%–90%, 30%–70%, 50%–50%, 70%–30%, and 100%–0%) of recycled asphalt pavement and recycled concrete aggregates, respectively, treated by four amounts of portland cement (0%, 2%, 4%, and 6%), were evaluated by impact echo, unconfined compression, and repeated-load triaxial test. From the test results, the range of P-wave velocity was between 5,500 in./s and 18,000 in./s, the compressive strength varied from 10 pounds per square inch (psi) and 415 psi, and the tangent modulus range was from 2.8 kips per square inch (ksi) to 41 ksi. Statistical models based on P-wave velocity data were derived for predicting elastic modulus, compressive strength, and resilient modulus. It was found that impact echo has significant potential in characterizing the strength and stiffness properties of cement-treated recycled base materials, which confirms the effectiveness of recycled materials in pavement applications.
13
Jiang, Chong, Wen-yan Wu, Jia-li He, and Lu-jie Chen. "Computation Method for the Settlement of a Vertically Loaded Pile in Sloping Ground." Advances in Civil Engineering 2020 (July 23, 2020): 1–10. http://dx.doi.org/10.1155/2020/2109535.
Full textAbstract:
Based on the hyperbolic curve tangent modulus method and the wedge stress theory, this paper proposes a calculation method for the settlement of a vertically loaded single pile in sloping ground. By establishing the relationship between the initial tangent modulus and the compression modulus of the slope soil, the tangent modulus of the slope soil is obtained combining with Mindlin-Geddes solution and Hansen formula, and the solution of the pile settlement in sloping ground is derived. Then, a series of numerical analyses are carried out to examine the feasibility of the proposed method. Finally, the effect of parameters is discussed in detail, including the slope angle, the distance of the pile from the slope crest, and the soil properties around the pile. The results show that the pile settlement will increase by increasing the slope angle or decreasing the distance of the pile from the slope crest, and the effect of the two parameters on the pile settlement is coupling-related. Besides, the compression modulus, cohesion, and internal friction angle of the soil around the pile are negatively related to the pile settlement and it is found that the compression modulus of the soil is the more influential parameter.
14
WADA, Chiharu, and Hideaki TAKAHASHI. "Initial Tangent Modulus and its Variation due to Water Content in Granitic Rock." Journal of the Mining Institute of Japan 102, no. 1175 (1986): 9–14. http://dx.doi.org/10.2473/shigentosozai1953.102.1175_9.
Full text
15
Bhattacharya, Aparajita, Grigori A. Medvedev, and James M. Caruthers. "TIME-DEPENDENT MECHANICAL BEHAVIOR OF CARBON BLACK FILLED ELASTOMERS." Rubber Chemistry and Technology 84, no. 3 (2011): 296–324. http://dx.doi.org/10.5254/1.3560020.
Full textAbstract:
Abstract An extensive set of time-dependent mechanical data was obtained for several filled SBR elastomers, including Mullins experiments, cyclic loading experiments, and stress relaxation. These comprehensive data enable critical evaluation of three classes of constitutive models. Viscoelastic models can naturally describe the hysteresis upon loading/reloading, but are unable to capture the large change in tangent modulus between the initial loading and the modulus just as the specimen is being unloaded. Elastic-damage models can capture the large change in tangent modulus just prior versus subsequent to unloading of a virgin sample, but can only parameterize the hysteresis on cyclic loading and are unable to predict strain rate effects and stress relaxation. A viscoelastic-damage model can predict the large change in tangent modulus upon reversal of the strain, hysteresis, strain rate effects, and stress relaxation; however, viscoelastic-damage models are unable to simultaneously predict the modest amount of hysteresis observed in cyclic experiments and the large amount of stress relaxation observed after loading to large deformations. The analysis indicates that constitutive models that include different deformation mechanics than the traditional elastic, viscoelastic, and damage processes will be needed to describe the full range of mechanical behavior exhibited by carbon black filled elastomers.
16
Ong, JEX, AU Yap, JY Hong, AH Eweis, and NA Yahya. "Viscoelastic Properties of Contemporary Bulk-fill Restoratives: A Dynamic-mechanical Analysis." Operative Dentistry 43, no. 3 (2018): 307–14. http://dx.doi.org/10.2341/16-365-l.
Full textAbstract:
SUMMARY This study investigated the viscoelastic properties of contemporary bulk-fill restoratives in distilled water and artificial saliva using dynamic mechanical analysis. The materials evaluated included a conventional composite (Filtek Z350), two bulk-fill composites (Filtek Bulk-fill and Tetric N Ceram), a bulk-fill giomer (Beautifil-Bulk Restorative), and two novel reinforced glass ionomer cements (Zirconomer [ZR] and Equia Forte [EQ]). The glass ionomer materials were also assessed with and without resin coating (Equia Forte Coat). Test specimens 12 × 2 × 2 mm of the various materials were fabricated using customized stainless-steel molds. After light polymerization/initial set, the specimens were removed from the molds, finished, measured, and conditioned in distilled water or artificial saliva at 37°C for seven days. The materials (n=10) were then subjected to dynamic mechanical testing in flexure mode at 37°C and a frequency of 0.1 to 10 Hz. Storage modulus, loss modulus, and loss tangent data were subjected to normality testing and statistical analysis using one-way analysis of variance/Dunnett's test and t-test at a significance level of p < 0.05. Mean storage modulus ranged from 3.16 ± 0.25 to 8.98 ± 0.44 GPa, while mean loss modulus ranged from 0.24 ± 0.03 to 0.65 ± 0.12 GPa for distilled water and artificial saliva. Values for loss tangent ranged from 45.7 ± 7.33 to 134.2 ± 12.36 (10−3). Significant differences in storage/loss modulus and loss tangent were observed between the various bulk-fill restoratives and two conditioning mediums. Storage modulus was significantly improved when EQ and ZR was not coated with resin.
17
Feng, Xin Jian, Jian Fang Fu, and Jian Lin Zhang. "A New Form of Genetic Algorithm for Back-Calculating Pavement Structure Modulus Based on Database Searching Theory." Applied Mechanics and Materials 193-194 (August 2012): 1090–94. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.1090.
Full textAbstract:
The Falling Weight Deflectometer (FWD) is designed to impart a load pulse to the pavement surface which simulates the load produced by a rolling vehicle wheel, wildly used in back-calculating pavement structure modulus. In this paper, a new form of Genetic Algorithm based on database searching theory is introduced. This method is not sensitive to initial values and it could identify the modulus effectively with establishing simple databases. By using a project measured data as an example, the result shows that this method is stable, convergent and practical. This method is better than the traditional method. It will be one of useful tools for the highway assessment.
18
Morgan, Elise F., Oscar C. Yeh, Wesley C. Chang, and Tony M. Keaveny. "Nonlinear Behavior of Trabecular Bone at Small Strains." Journal of Biomechanical Engineering 123, no. 1 (2000): 1–9. http://dx.doi.org/10.1115/1.1338122.
Full textAbstract:
Study of the behavior of trabecular bone at strains below 0.40 percent is of clinical and biomechanical importance. The goal of this work was to characterize, with respect to anatomic site, loading mode, and apparent density, the subtle concave downward stress–strain nonlinearity that has been observed recently for trabecular bone at these strains. Using protocols designed to minimize end-artifacts, 155 cylindrical cores from human vertebrae, proximal tibiae, proximal femora, and bovine proximal tibiae were mechanically tested to yield at 0.50 percent strain per second in tension or compression. The nonlinearity was quantified by the reduction in tangent modulus at 0.20 percent and 0.40 percent strain as compared to the initial modulus. For the pooled data, the mean±SD percentage reduction in tangent modulus at 0.20 percent strain was 9.07±3.24 percent in compression and 13.8±4.79 percent in tension. At 0.40 percent strain, these values were 23.5±5.71 and 35.7±7.10 percent, respectively. The magnitude of the nonlinearity depended on both anatomic site p<0.001 and loading mode p<0.001, and in tension was positively correlated with density. Calculated values of elastic modulus and yield properties depended on the strain range chosen to define modulus via a linear curve fit p<0.005. Mean percent differences in 0.20 percent offset yield strains were as large as 10.65 percent for some human sites. These results establish that trabecular bone exhibits nonlinearity at low strains, and that this behavior can confound intersite comparisons of mechanical properties. A nonlinear characterization of the small strain behavior of trabecular bone was introduced to characterize the initial stress–strain behavior more thoroughly.
19
Eslami, M. R., and M. Shariyat. "Elastic, Plastic, and Creep Buckling of Imperfect Cylinders Under Mechanical and Thermal Loading." Journal of Pressure Vessel Technology 119, no. 1 (1997): 27–36. http://dx.doi.org/10.1115/1.2842263.
Full textAbstract:
Based on the concept of secant and tangent modulus, the nonlinear equilibrium and stability equations of thin cylindrical shells under axial compression, external pressure, or external fluid pressure are derived. The resulting equations are applicable to shells without length limitation as the rotations and transverse shears are included in the derivations. The reduction factors for plastic and creep buckling are then obtained. A procedure for determining secant and tangent modulus in the very general case of elastic, plastic, or creep stress in the presence of temperature gradient is proposed. Then, using Donnell’s nonlinear theory of shells, the effect of initial imperfection on the strength of the elastic shell is discussed. The foregoing results are extended to plastic and creep buckling of cylindrical shells of arbitrary length and temperature gradient. Some design curves are proposed using the obtained equations. Finally, the present results are compared with available results in the literature and the accuracy of the method is examined.
20
Jiang, Xin, Kang Yao, Hanyan Gu, Zhenkun Li, and Yanjun Qiu. "Comparison of Nonlinear Analysis Algorithms for Two Typical Asphalt Pavement Analysis Programs." Baltic Journal of Road and Bridge Engineering 15, no. 4 (2020): 225–51. http://dx.doi.org/10.7250/bjrbe.2020-15.502.
Full textAbstract:
Two representative programs, MICH-PAVE and KENLAYER, are selected and compared to many key aspects of their analysis algorithms to achieve an in-depth understanding of the features of the Finite Element Method and elastic layered system theory in nonlinear material analysis of the structure of asphalt pavement. Furthermore, by conducting a case study, the impact of using different analysis methods on the calculation results is presented. Moreover, the feasibility of the equivalent resilient modulus obtained by the Finite Element Method is discussed. The results show that the difference among the nonlinear analysis algorithms used by the two software packages is mainly reflected in the determination of the initial resilient modulus, the stress correction, and the convergence condition. Besides, the Finite Element Method could consider the variation of the resilient modulus induced by the change in the stress condition in both the radial and the depth directions simultaneously. In contrast, the theory of the elastic layered system only considers the dependence of the resilient modulus on the stress in the depth direction. Additionally, the use of diverse nonlinear analysis methods has different levels of impact on mechanical responses. Finally, the equivalent resilient modulus obtained by nonlinear analysis can be used to calculate mechanical responses of pavement structure except the surface deflection in a linear analysis.
21
Shalabi, Faisal, Javed Mazher, Kaffayatullah Khan, et al. "Cement-Stabilized Waste Sand as Sustainable Construction Materials for Foundations and Highway Roads." Materials 12, no. 4 (2019): 600. http://dx.doi.org/10.3390/ma12040600.
Full textAbstract:
In this study, cement-treated waste sand as a by-product material produced from Al-Ahsa quarries (Saudi Arabia) was experimentally tested and investigated as a base course material for the foundation of structures and roads. The study aimed to use the waste sand as a construction material by improving its strength, bearing capacity, and stiffness. The waste sand was mixed with different percentages of Portland cement content (0, 2, 4, 6, and 8%) at the maximum dry density and optimum water content of the standard Proctor compaction conditions of a non-treated sample. Unconfined compressive strength and California Bearing Ratio (CBR) tests for different curing times were conducted. X-ray diffraction (XRD), laser-scanning microscopy (LSM), and X-ray spectroscopy (XPS) were used to explore the microstructure and composition of the treated sand. The results showed that the compressive strength, initial tangent modulus, and CBR of the treated sand increase with the increase in cement content and curing time. Furthermore, good correlations were established among the strength, initial tangent modulus, and CBR. Based on the obtained results, cement-stabilized waste sand is a potential material for use in construction. This is expected to save the environment and reduce the cost of road construction.
22
Cox, G. F. N., J. A. Richter, W. F. Weeks, and M. Mellor. "A Summary of the Strength and Modulus of Ice Samples From Multi-Year Pressure Ridges." Journal of Energy Resources Technology 107, no. 1 (1985): 93–98. http://dx.doi.org/10.1115/1.3231169.
Full textAbstract:
Over two hundred unconfined compression tests were performed on vertical ice samples obtained from 10 multi-yr pressure ridges in the Beaufort Sea. The tests were performed on a closed-loop electrohydraulic testing machine at two strain rates (10−5 and 10−3 s−1) and two temperatures (−20° and −5°C). This paper summarizes the sample preparation and testing techniques used in the investigation and presents data on the compressive strength and initial tangent modulus of the ice.
23
Haneefa, M. K., S. Girish, R. V. Ranganath, and B. Saikia. "A Structural Dynamic Approach to Evaluate Modulus of Elasticity of Cantilever Beam." Applied Mechanics and Materials 852 (September 2016): 483–88. http://dx.doi.org/10.4028/www.scientific.net/amm.852.483.
Full textAbstract:
The modulus of elasticity is an important property of any structural member or machine component. It has a vital role in designing the structural components or machine components for their specific use. This paper discusses evaluation of modulus of elasticity of cantilever beams made out of Self-Compacting Concrete (SCC) using a structural dynamic approach – the free vibration test. The concept of free flexural vibration essentially involves setting up a specimen (beam) into ‘free vibration’ by imparting an initial condition, such that the specimen vibrates in its fundamental natural frequency. The digital data were stored using an efficient data acquisition system (Daisy lab version 5 software) and processed using Fast Fourier Transformation (FFT) (Acceleration v/s Time). The fundamental natural frequencies thus obtained were used to evaluate dynamic modulus of elasticity of SCC specimens using well established basic equations of structural dynamics. The study revealed that the dynamic modulus of elasticity for the cantilever beams were equal to the initial tangent modulus obtained by conventional compresso-meter method as per ASTM C 469-02. Moreover, the free vibration tests exhibited high consistency and repeatability. This technique can be of potential use as Non-Destructive Testing (NDT) for monitoring the health of in situ structures or machine components.
24
Yan, Lei, Liansheng Liu, Shenghui Zhang, Depei Lan, and Jiangchao Liu. "Testing of Weakly Weathered Granites of Different Porosities Using a Split Hopkinson Pressure Bar Technique." Advances in Civil Engineering 2018 (September 2, 2018): 1–11. http://dx.doi.org/10.1155/2018/5267610.
Full textAbstract:
Nuclear magnetic resonance (NMR) and damage impact testing, using a split Hopkinson pressure bar (SHPB) technique, were conducted on weakly weathered granites of different porosities. Based on this, this study determined and analysed the pore structure and distribution, propagation characteristics of stress waves, changes in initial tangent modulus, and energy dissipation in weakly weathered granites of different porosities. The research demonstrated that the nature of the internal porosity of weakly weathered granites changed with total porosity. Pore structure significantly influenced the amplitude of reflected waves and distortion of transmitted waves. Under constant-damage impact loads, the initial tangent modulus decreased with increasing porosity, whereas the stress-strain curves, after reaching the peak stress, had similar shapes. Peak stress and average strain rate showed a strong power-law correlation with porosity, and peak stress decreased in a power-law correlation with the increase of average strain rate. In other words, the difference in average strain resulted from different porosities when the incident energy was same, and the average strain was negatively correlated with porosity. Under damaging impact, the energy absorbed per unit volume decreased with increasing porosity. The research results reveal dynamic characteristics of natural porous rocks under damage impacts, which provide a reference for studying damage effects of porous rocks under the effects of stress waves.
25
Cox, G. F. N., and J. A. Richter-Menge. "Tensile Strength of Multi-Year Pressure Ridge Sea Ice Samples." Journal of Energy Resources Technology 107, no. 3 (1985): 375–80. http://dx.doi.org/10.1115/1.3231204.
Full textAbstract:
Thirty-six constant strain-rate uniaxial tension tests were performed on vertically oriented multi-year pressure ridge samples from the Beaufort Sea. The tests were performed on a closed-loop electro-hydraulic testing machine at two strain rates (10−5 and 10−3 s−1) and two temperatures (−20° and −5°C). This paper summarizes the sample preparation and testing techniques used in the investigation and presents data on the tensile strength, initial tangent modulus, and failure strain of the ice.
26
Araújo, S. S., G. N. Guimarães, and A. L. B. Geyer. "Influence of the type of measuring device in determining the static modulus of elasticity of concrete." Revista IBRACON de Estruturas e Materiais 5, no. 5 (2012): 555–75. http://dx.doi.org/10.1590/s1983-41952012000500001.
Full textAbstract:
This paper presents a comparative analysis of the results obtained in static modulus of elasticity tests of plain concrete cylindrical specimens. The purpose of this study is to identify and evaluate the influence of several factors involved in modulus of elasticity tests such as the strain measurement device used (dial indicators, electrical surface bonded strain gages, externally fixed strain gages and linear variation displacement transducer - LVDT), the type of concrete (Class C30 and Class C60) and cylindrical specimen size (100 mm x 200 mm and 150 mm x 300 mm). The modulus tests were done in two different laboratories in the Goiânia, GO region and were performed according to code ABNT NBR 8522:2008, which describes the initial tangent modulus test, characterized by strains measured at tension values of 0.5 MPa and 30% of the ultimate load. One hundred and sixty specimens were tested with statistically satisfactory results. It was concluded that the type of strain measurement device greatly influenced the modulus of elasticity results. Tests in specimens 100 mm x 200 mm showed highest statistical variation.
27
Sounthararajah, Arooran, Nhu Nguyen, Ha Hong Bui, Peerapong Jitsangiam, Gordon L. M. Leung, and Jayantha Kodikara. "Effect of Cement on the Engineering Properties of Pavement Materials." Materials Science Forum 866 (August 2016): 31–36. http://dx.doi.org/10.4028/www.scientific.net/msf.866.31.
Full textAbstract:
It is well known that cement stabilization of granular materials is a cost-effective and environmentally friendly technique for the highway construction. However, the testing and design methods for these stabilized materials have not been sufficiently advanced scientifically, which hinders their full potential application. The proper characterization of the stabilized pavement materials is vital for the successful pavement design and construction. This paper presents the results from an experimental study on the effect of cement stabilization on pavement materials in terms of engineering properties essential for use in mechanistic design of road pavements. The test results from this study revealed that the index and shrinkage properties of the pavement materials are significantly influenced by cement content, and the tensile and compressive resistances of a cement stabilized pavement base layer increase significantly with the increasing cement content and increasing curing period. Based on the test results, it is concluded that the flexural modulus/UCS and the flexural strength/UCS ratios of the cement stabilized pavement materials depend on the material, age of curing, initial stage of the compacted material and laboratory testing practices.
28
Zheng, Yao, and Hong Zheng. "Steel Rod Stability and Inelastic Buckling Study." Applied Mechanics and Materials 357-360 (August 2013): 626–30. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.626.
Full textAbstract:
Research on stability problem, has put forward the famous bar under axial pressure formula from the middle of the eighteenth Century Euler critical force, more than 200 years, the elastic range but recognize that Euler's formula is only suitable for the material, but it took more than a hundred years. Study on the inelastic critical load of column, double modulus theory and the tangent modulus theory. These theories are starting from the ideal straight rod, and practical bar called " defects exist various accidental eccentricity " ( such as physical and geometrical aspects of the initial deflection rod, pressure asymmetry in aspects of material unevenness, residual stress) is not consistent. Thus the utility pressure bar, should according to the eccentric pressing rod is considered more practical.
29
Lee, Yung-Chien, Y. Richard Kim, and S. Ranji Ranjithan. "Dynamic Analysis-Based Approach To Determine Flexible Pavement Layer Moduli Using Deflection Basin Parameters." Transportation Research Record: Journal of the Transportation Research Board 1639, no. 1 (1998): 36–42. http://dx.doi.org/10.3141/1639-04.
Full textAbstract:
Most of the deflection analysis programs used today to analyze falling weight deflectometer (FWD) data are based on static analysis, which often underestimates the subgrade strength. Unfortunately, dynamic analysis usually involves complex calculations and requires significant computation time, thus making it impractical for routine applications. A methodology based on deflection basin parameters and artificial neural networks (ANN) for processing dynamic FWD measurements to estimate layer strengths is presented in this paper. Two-dimensional, dynamic finite element analysis using the ABAQUS program was employed to develop the deflection information for this study. Unlike the majority of the existing backcalculation programs that iteratively adjust the layer moduli to match the measured deflections, the proposed method first determines the subgrade modulus by means of two deflection basin parameters—Base Damage Index and Shape Factor F2—and then applies the estimated subgrade modulus and other parameters as input variables to a trained ANN to estimate the upper layers’ moduli. In contrast to other programs that require the input of seed values for layer moduli, this method does not require initial estimates as input. A set of field FWD measurements were analyzed both by this method and by the MODULUS program. Results reveal that the proposed method is able to better predict the asphalt concrete layer modulus while taking into account the dynamic effects of the FWD test. This method is also shown to be computationally efficient, which makes it applicable for routine tasks and field use.
30
Varma, D. S., and V. K. Dhar. "Nylon 6/PET Polymer Blends: Mechanical Properties of Fibers." Textile Research Journal 58, no. 5 (1988): 274–79. http://dx.doi.org/10.1177/004051758805800505.
Full textAbstract:
Nylon 6/PET (polyethylene terephthalate) polymer blends (PET varying from 10–50%) were melt spun into fibers. Their tensile properties (at room temperature) and dynamic mechanical properties (at 110 Hz from room temperature to 200°C) were studied. An increase in the initial modulus with increasing PET content was observed. The tenacity showed an increase and then a subsequent decrease after 70/30 nylon 6/PET composition. The blend fibers showed lower extensibility. Various theories connecting modulus and tenacity (independently) with composition, interfacial adhesion, and dispersed phase morphology helped to explain the observed tensile properties. The loss tangent maxima is shifted to a higher temperature with increased PET content in the blend fiber, while the relaxation peaks become broader up to a certain composition. Further, the storage modulus increases throughout with the increase in the PET content. The Takayanagi series and parallel models have been applied, and the results describe the structural and morphological features of the blend fiber, besides explaining some of the properties.
31
Ghanizadeh, Ali Reza. "An Optimization Model for Design of Asphalt Pavements Based on IHAP Code Number 234." Advances in Civil Engineering 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/5942342.
Full textAbstract:
Pavement construction is one of the most costly parts of transportation infrastructures. Incommensurate design and construction of pavements, in addition to the loss of the initial investment, would impose indirect costs to the road users and reduce road safety. This paper aims to propose an optimization model to determine the optimal configuration as well as the optimum thickness of different pavement layers based on the Iran Highway Asphalt Paving Code Number 234 (IHAP Code 234). After developing the optimization model, the optimum thickness of pavement layers for secondary rural roads, major rural roads, and freeways was determined based on the recommended prices in “Basic Price List for Road, Runway and Railway” of Iran in 2015 and several charts were developed to determine the optimum thickness of pavement layers including asphalt concrete, granular base, and granular subbase with respect to road classification, design traffic, and resilient modulus of subgrade. Design charts confirm that in the current situation (material prices in 2015), application of asphalt treated layer in pavement structure is not cost effective. Also it was shown that, with increasing the strength of subgrade soil, the subbase layer may be removed from the optimum structure of pavement.
32
Zhang, Yu Wei, Qing Guo Yang, and Zhi Zhong Tu. "Research on the Temperature Stress Field of Interface End between Asphalt Concrete Overlay and Concrete Pavement." Advanced Materials Research 160-162 (November 2010): 1704–11. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1704.
Full textAbstract:
For the interface end formed after paving asphalt overlay on cement concrete pavement, the stress field of interface end is very important for both structural analysis and interface design when the temperature drops. The stress field of interface end can be gotten with the crack-tip field theory that consider displacement continuation and stress equality on each side of interface, but it needs further verification to prove whether the initial stress field can satisfy far field boundary condition when temperature dropping. In conditions of different material properties, different plane dimension and different thickness of asphalt overlay the stress field is calculated with the finite element method (FEM), and the results show that the forms of theoretical solution can exactly describe stress field of the interface end when temperature dropping. The stress field of interface end indicates that when the elastic modulus of asphalt overlay becomes lager, the stress singularity’s degree of interface end will reduce. As for the interface end formed after paving asphalt concrete overlay on the concrete pavement, improving the elastic modulus of asphalt overlay is beneficial.
33
BHAT, SUBRAYA KRISHNA, NORIYUKI SAKATA, and HIROSHI YAMADA. "IDENTIFICATION OF UNIAXIAL DEFORMATION BEHAVIOR AND ITS INITIAL TANGENT MODULUS FOR ATHEROMATOUS INTIMA IN THE HUMAN CAROTID ARTERY AND THORACIC AORTA USING THREE-PARAMETER ISOTROPIC HYPERELASTIC MODELS." Journal of Mechanics in Medicine and Biology 20, no. 03 (2020): 2050014. http://dx.doi.org/10.1142/s0219519420500141.
Full textAbstract:
Uniaxial stretching tests are used for mechanical identification of small fibrous regions of atheromatous arteries. Material constants in isotropic hyperelastic models are determined to minimize the fitting error for the stress–strain curve. We developed a novel method to better characterize the material constants in typical forms of Yeoh, Ogden, Chuong–Fung (CF) and Gasser–Ogden–Holzapfel (GOH) isotropic hyperelastic models for fibrous caps and normal intimal layers from human carotid artery and thoracic aorta by incorporating Young’s modulus, i.e., the initial tangent modulus of uniaxial stress–strain relationships, as one of three material constants. We derived a unified, isotropic form for the anisotropic exponential-type strain energy density functions of CF and GOH models. The uniaxial stress–strain relationship equations were expanded to Maclaurin series to identify Young’s modulus as a coefficient of the linear term of the strain and to examine the roles of the material constants in the nonlinear function. The remaining two material constants were determined by curvefitting. The incorporation of Young’s modulus into the CF and GOH models gave reasonable curvefitting, with errors [Formula: see text], whereas large errors ([Formula: see text]) were observed in one case for the Yeoh model and in two cases for the Ogden model.
34
Wang, Tianzuo, Mengya Xue, Peng Sha, Fei Xue, and Linxiang Wang. "Study on the Influence of Different Prophase Stress Levels on the Fatigue Damage Characteristics of Granite." Shock and Vibration 2021 (June 5, 2021): 1–12. http://dx.doi.org/10.1155/2021/5513910.
Full textAbstract:
In order to reveal the influence of prophase stress levels on the fatigue damage characteristics of granite, uniaxial fatigue tests of granite with different prophase stress levels were carried out on the basis of the MTS 815.04 rock mechanics test system. The results show that, under the same number of cycles, the failure degree increases with the increase of the prophase stress level. Under the low upper limit of cyclic stress, the tangent modulus and dissipated energy increase significantly with the increase of prophase stress level at the early stage of the cycle loading, while the increasing trend is not obvious with the increase of prophase stress level at the late stage. Under the high upper limit of cyclic stress, the tangent modulus and dissipated energy are less affected by the prophase stress level. The development trend of elastic release energy is not obvious with the increase of prophase stress level, which is less affected by the number of cycles. From the damage parameters defined by dissipative energy, under the low upper limit of cyclic stress, the initial damage is less affected by the prophase stress level. With the increase of the number of cycles, the influence of the prophase stress level on the development trend of the damage variable increases gradually. And the development trend of damage variables shows “C-shaped” damage.
35
Saha, Indrajit, and Sanjib Kumar Sarkar. "Investigation of physico-mechanical properties of natural palm fiber reinforced polyvinyl chloride composites." Journal of Bangladesh Academy of Sciences 38, no. 1 (2014): 83–92. http://dx.doi.org/10.3329/jbas.v38i1.20215.
Full textAbstract:
Fiber reinforced polymer composites played a dominant role in a variety of applications for their high specific strength and modulus. The present work describes the effects of palm fiber addition on physico-mechanical properties of polyvinyl chloride (PVC) composites. The tensile strength and Youngs modulus of the fabricated products increased, while the bulk density, flexural strength and tangent modulus decreased with the increase of fiber addition. The tensile strain decreased with the increase of fiber addition up to 10% and after that it remained nearly constant, while flexural strain remained increasing. There was an initial differential thermal analysis (DTA) peak for both palm fiber and composite, whereas PVC did not have that peak due to water absorption. Thermal analysis of PVC-palm fiber composites has shown that thermal degradation of PVC started ahead of palm fiber. The thermal stability of composite was found to be the average of palm fiber and PVC foam sheet DOI: http://dx.doi.org/10.3329/jbas.v38i1.20215 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 1, 83-92, 2014
36
Tian, Yong, Rangang Yu, Yin Zhang, and Xinbo Zhao. "Research on damage evolution of deep formation rock based on acoustic emission test." International Journal of Damage Mechanics 30, no. 1 (2020): 145–59. http://dx.doi.org/10.1177/1056789520957381.
Full textAbstract:
The study of rock damage evolution is of great significance in the field of underground engineering. In this paper, the damage development of deep formation rock was quantitatively evaluated by acoustic emission (AE) test. The Young’s modulus of the test rock specimens under ideal intact state was obtained by assuming a linear relationship between the AE rate parameter and the damage variation based on the rate process theory. Through the multi-stage cyclic loading test, the damage parameters corresponding to the peak stress of the previous stage were calculated by using the tangent modulus at the initial moment. The results showed that there was abrupt transition stage of damage development with the linear increase of stress. The damage parameter curves of rock specimens during loading process were obtained by using the method of cumulative AE energy, and the development trend of the curves was analyzed simply by combining the concepts of crack initiation stress and crack damage stress. Comparing the two methods of obtaining damage parameters by using cyclic loading test and cumulative AE energy, the results of them were highly consistent except for some deviation in the initial and final stages.
37
Zofka, Adam, Maciej Maliszewski, Ewa Zofka, Miglė Paliukaitė, and Laura Žalimienė. "GEOGRID REINFORCEMENT OF ASPHALT PAVEMENTS." Baltic Journal of Road and Bridge Engineering 12, no. 3 (2017): 181–86. http://dx.doi.org/10.3846/bjrbe.2017.22.
Full textAbstract:
Geogrid materials applied within asphalt layers defer or prevent the occurrence of reflective cracking. The contribution of this work significantly adds to extending pavement serviceability and improving benefit/cost analysis. Since 1970s many studies have demonstrated the benefits of geogrid reinforcement in asphalt pavements, but this knowledge did not translate to their extensive usage in the actual construction practice. Among potential reasons are higher initial costs, lack of in-depth understanding of working mechanism within adjacent asphalt layers and lack of commonly standard design procedures. This paper presents a recent study, which investigated the effect of geogrid reinforcement on asphalt mixture specimens. Two types of laboratory experiments were conducted, namely monotonic (strength and fracture) testing and cyclic (fatigue and modulus) testing. The results demonstrated a significant strengthening contribution of geogrid, which was observed regarding fracture energy results and terminal deflections in the fatigue testing. This paper also presents a short example connecting pavement deflections with the allowable axle loading (also known as fatigue life) to demonstrate the practical implications of geogrid reinforcement. The undertaken analysis shows the reduction of pavement deflections due to the geogrid application, which potentially leads to a significant extension of pavement fatigue life. Paper concludes with several recommendations for further work in the area of geogrid reinforcement.
38
Zheng, Qi Wen, Chen Wang, and Jian Wei Zhang. "The Strength and Stress-Strain Behavior of the Cemented Rockfill." Advanced Materials Research 598 (November 2012): 565–68. http://dx.doi.org/10.4028/www.scientific.net/amr.598.565.
Full textAbstract:
The cemented rockfill is mixed with cement, water and the siltstone rockfill with a certain mixing proportion. To study the strength and stress-strain behavior of the cemented rockfill, two groups of triaxial tests are carried out under the saturated and consolidated-drained conditions. One group specimens don’t include cement while the other group specimens include. The test results show that the cemented rockfill is a kind of elastoplastic material and the structure of the cemented rockfill is forced due to the effect of cementation. Compared with rockfill, the initial tangent elastic modulus, strength and cohesion of the cemented rockfill increase apparently, the residual strength and internal friction angle of the cemented rockfill increase a little, the maximum volume strain of the cemented rockfill decreases apparently.
39
Richter-Menge, J. A. "Confined Compressive Strength of Horizontal First-Year Sea Ice Samples." Journal of Offshore Mechanics and Arctic Engineering 113, no. 4 (1991): 344–51. http://dx.doi.org/10.1115/1.2919940.
Full textAbstract:
A total of 110 first-year sea ice samples from Prudhoe Bay, Alaska, were tested in unconfined and confined constant strain rate compression. All of the tests were performed in the laboratory on a closed-loop electrohydraulic testing machine at −10°C. The confined tests were performed in a conventional triaxial cell (σ1>σ2=σ3) that maintained a constant ratio between the radial and axial stress (σ2/(σ1)=constant) to simulate true loading conditions. Three strain rates (10−2, 10−3, and 10−5/s) and three σ2/σ1 ratios (0.25, 0.50, and 0.75) were investigated. This paper summarizes the field sampling and testing techniques and presents data on the effect of confinement on the compressive strength, initial tangent modulus, and failure strain of the ice.
40
Yuan, Li Hao, Zhi Xin Xiong, Lei Song, and Zhi Hui Dong. "A Simplified Method for Calculating Ultimate Strength of Pressure Hull in Deep-Sea Manned Submersible." Applied Mechanics and Materials 160 (March 2012): 17–24. http://dx.doi.org/10.4028/www.scientific.net/amm.160.17.
Full textAbstract:
Based on the strain energy density theory, the connotation of tangent modulus theory is developed. At critical equilibrium state, a dimensionless number Φt of a structure under pressure is introduced in this paper. Derived from the stress-strain curve of material, a four-parameter formula that contains Φt is established. This formula is referred to as the function of strength utilization ratio that may be used for calculating the inelastic buckling of deep submersible pressure hull.Φt can be used to express the effect of initial imperfection of the shell and to guide the experimental study. Compared with the data from some experiments or other methods, it has demonstrated that the method given by this paper is more precise and convenient for predicting the failure of thin and moderately thick shell under pressure.
41
Gizejowski, Marian A., Czeslaw J. Branicki, Anna M. Barszcz, and Pawel Krol. "ADVANCED ANALYSIS OF STEEL FRAMES WITH EFFECTS OF JOINT DEFORMABILITY AND PARTIAL STRENGTH ACCOUNTED FOR." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 10, no. 3 (2004): 199–208. http://dx.doi.org/10.3846/13923730.2004.9636307.
Full textAbstract:
The paper summarises the current progress in methods of advanced analysis for design of frames with semirigid joints. The methods presented in the paper belong to general second‐order refined plastic‐hinge methods that allow for the combined effects of joint stiffness degradation and distributed plasticity along the member length as well as across the member sections. The advanced analysis for steel frame design, proposed by the authors, is based on the spring‐in‐series model. The effect of joint semi‐rigidity and partial strength is taken care of by specifying certain values of the initial stiffness, ultimate moment and the shape factor of the moment‐rotation characteristic for the spring representing the joint. The effect of imperfections affecting the performance of imperfect structural members in compression is modelled by the application of a simplified tangent modulus concept combined with the reduction of the initial value of the elasticity modulus. The effect of residual stresses is taken care of by specifying certain values of the shape parameter for the moment‐rotation characteristic of the spring representing the gradual yielding of the member. It is dependent upon the cross‐section type and fabrication method (ie upon the residual stress pattern resulting from rolling or welding processes). A case study analysis is presented. Concluding remarks referring to the application of advanced analysis in design, pertaining to the study case considered, are drawn.
42
Yang, Bin, Qin Shou Huang, Bin Xiong, and Hua Xu. "Analysis on the Effect of Parameters Variation on Dynamic Stress Intensity Factor of Asphalt Overlay Reflective Crack." Applied Mechanics and Materials 52-54 (March 2011): 1092–96. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1092.
Full textAbstract:
With dynamic stress intensity factor (DSIF) as a characteristic parameter, this paper makes an analysis on the effect of parameters variation of vehicle speed, asphalt overlay thickness, modulus and old cement concrete pavement joint width on asphalt overlay reflective crack by investigating the variation law of reflective crack of asphalt overlay structure suffer wheel load. The results show that: the maximum dynamic stress intensity factor decreases with the increase of speed. Numerical value of maximum dynamic stress intensity factor is larger than the corresponding value of the static load. The longer the initial crack, the less the times of sustaining load of the same extending length. The increase of asphalt overlay thickness can reduce the value of dynamic stress intensity factor to a certain extent. With the augmentation of asphalt overlay modulus, the effect of dynamic load on reflective crack can be reduced in some degree. Dynamic stress intensity factor increases with the increase of joint width.
43
Siami, Majid, Kamal Jahani, and Mousa Rezaee. "Identifying the parameters of viscoelastic model for a gel-type material as representative of cardiac muscle in dynamic tests." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 235, no. 10 (2021): 1205–16. http://dx.doi.org/10.1177/09544119211025868.
Full textAbstract:
In this paper, mechanical parameters of a calf heart muscle are identified and a gel-type material as the representative of the cardiac muscle in dynamic tests is introduced. The motivation of this study is to introduce a replacement material of the heart muscle to use in experimental studies of the leadless pacemaker. A particular test setup is developed to capture the experimental data based on the stress relaxation test method where its outputs are time histories of the force and displacement. The standard linear solid model is used for mathematical modeling of the heart muscle sample and a gel-type material specimen namely α-gel. Five tests with different strain history [Formula: see text] are performed by regarding and disregarding the influence of the initial ramp of the loading. The mechanical parameters of the standard linear solid model were identified with precise curve fitting. Consideration of the initial ramp significantly influences the consequences and they are so close to their experimental counterparts. The identified parameters of the standard linear solid model by regarding the influence of the initial ramp for the gel-type material are within an acceptable range for the viscoelastic properties of the calf heart tissue. These results show that the gel-type material has the potential to represent the cardiac muscle in the leadless pacemaker experimental studies. Dynamic mechanical analysis is used to characterize the dynamic viscoelastic properties for the gel by utilizing the identified parameters with taking into account the initial ramp in the frequency domain. Results show that Storage modulus, Loss modulus, and Loss tangent are strongly frequency-dependent especially at low-frequency around the heartbeat frequency range (0–2 Hz).
44
Kimpara, Hideyuki, Masami Iwamoto, Isao Watanabe, et al. "Effect of Assumed Stiffness and Mass Density on the Impact Response of the Human Chest Using a Three-Dimensional FE Model of the Human Body." Journal of Biomechanical Engineering 128, no. 5 (2006): 772–76. http://dx.doi.org/10.1115/1.2264394.
Full textAbstract:
The mass density, Young’s modulus (E), tangent modulus (Et), and yield stress (σy) of the human ribs, sternum, internal organs, and muscles play important roles when determining impact responses of the chest associated with pendulum impact. A series of parametric studies was conducted using a commercially available three-dimensional finite element (FE) model, Total HUman Model for Safety (THUMS) of the whole human body, to determine the effect of changing these material properties on the predicted impact force, chest deflection, and the number of rib fractures and fractured ribs. Results from this parametric study indicate that the initial chest apparent stiffness was mainly influenced by the stiffness and mass density of the superficial muscles covering the torso. The number of rib fractures and fractured ribs was primarily determined by the stiffness of the ribcage. Similarly, the stiffness of the ribcage and internal organs contributed to the maximum chest deflection in frontal impact, while the maximum chest deflection for lateral impact was mainly affected by the stiffness of the ribcage. Additionally, the total mass of the whole chest had a moderately effect on the number of rib fractures.
45
Huang, Bin, Yuting Zhang, Tian Qi, and Hongxing Han. "Static and Dynamic Properties and Temperature Sensitivity of Emulsified Asphalt Concrete." Advances in Materials Science and Engineering 2018 (June 10, 2018): 1–9. http://dx.doi.org/10.1155/2018/7067608.
Full textAbstract:
Asphalt concrete is a typical rheological material, which is hard brittle at low temperature and reflects soft plastic facture at high temperature; the temperature has a great influence on the mechanical properties of asphalt concrete. In order to eliminate the environmental pollution caused by hot asphalt construction, cationic emulsified asphalt can be used. This paper transforms the temperature control system for static and dynamic triaxial test equipment, which has achieved static and dynamic properties of emulsified asphalt concrete under different temperatures, and researched the temperature sensitivity of emulsified asphalt concrete materials including static stress-strain relationship, static strength, dynamic modulus of elasticity, damping ratio, and so on. The results suggest that (1) temperature has a great influence on the triaxial stress-strain relationship curve of the asphalt concrete. The lower the temperature, the greater the initial tangent modulus of asphalt concrete and the higher the intensity; the more obvious the softening trend, the smaller the failure strain of the specimen and the more obvious the extent of shear dilatancy. When the temperature is below 15.4°C, the temperature sensitivity of the modulus and strength is stronger significantly. (2) With the temperature rising, the asphalt concrete gradually shifts from an elastic state to a viscoelastic state, the dynamic modulus gradually reduces, and the damping ratio increases. When the temperature is above 15.4°C, the temperature sensitivity is obviously stronger for the dynamic elastic modulus and damping ratio. (3) The static and dynamic properties of asphalt concrete are very sensitive to the temperature. The test temperature should be made clear for the static and dynamic tests of asphalt concrete. The specimen temperature and the test ambient temperature must be strictly controlled.
46
Wang, Xing Chen, Ri Qing Xu, and Jing Lin Qian. "Modified Duncan-Chang Model Considering Physical Properties of Saturated Clays." Applied Mechanics and Materials 416-417 (September 2013): 1746–52. http://dx.doi.org/10.4028/www.scientific.net/amm.416-417.1746.
Full textAbstract:
A series of undrained triaxial compression tests of saturated clays under different conditions were performed to study whether it is possible to determine parameters specifying Duncan-Chang model simply by using the physical parameters. The test results show that both the initial tangent modulus and peak deviatoric stress decrease with increasing initial void ratio and plasticity index of the soil under the same confining pressure. Whereas, they increase with increasing confining pressure of the soil with the same initial void ratio and plasticity index. A new synthesized physical parameter λ is defined based on the test results in this work. The functional relationships among the parameters K, peak deviatoric stress in Duncan-Chang model and the parameter λ are established to develop a modified Duncan-Chang model by considering physical properties of soil. In this model, only two input parameters, i.e., λ and the damage ratio Rf, are needed to predict the stress-strain relationships of the soil. In order to check the accuracy of the proposed model, laboratory tests were conducted to evaluate against the predicted results. The results show that the stress-strain relationships of saturated clays can be well described by the proposed model.
47
Yang, Jie, Xin Cai, Xing-Wen Guo, and Jin-Lei Zhao. "Effect of Cement Content on the Deformation Properties of Cemented Sand and Gravel Material." Applied Sciences 9, no. 11 (2019): 2369. http://dx.doi.org/10.3390/app9112369.
Full textAbstract:
Knowing the deformation properties of cemented sand and gravel (CSG) material can help construct reasonable constitutive models for the material, which can be used to simulate the structural performance of various practical projects including CSG dams. In this study, to investigate the effect of cement content on the deformation properties of CSG material, we employ triaxial compressive tests for cement contents of 20, 40, 60, 80, and 100 kg/m3 with a confining pressure range of 0.3–1.2 MPa, and theoretically analyze the results by the regression analysis prediction method. Here, we show that both cement content and confining pressure influence the deformation properties of CSG material: for an increase in cement content, the failure strain decreases and brittleness of CSG material increases; the initial modulus of the CSG material increased exponentially with increasing cement content or confining pressure; the peak volumetric strain and its corresponding axial strain increase linearly with increasing confining pressures, which decrease with increasing cement content; the initial tangent volumetric ratio can also be determined by the peak volumetric strain and its corresponding axial strain.
48
Polovyi, A. O., N. V. Matiushevski, and N. G. Lisachenko. "Features of nonlinear in-plane shear deformation of a unidirectional and orthogonally reinforced polymer sheets of composite materials." Industrial laboratory. Diagnostics of materials 87, no. 5 (2021): 47–55. http://dx.doi.org/10.26896/1028-6861-2021-87-5-47-55.
Full textAbstract:
A comparative analysis of typical stress-strain diagrams obtained for in-plain shear of the 25 unidirectional and cross-ply reinforced polymer matrix composites under quasi-static loading was carried out. Three of them were tested in the framework of this study, and the experimental data on other materials were taken from the literature. The analysis of the generalized shear-strength curves showed that most of the tested materials exhibit the similar deformation pattern depending on their initial shear modulus: a linear section is observed at the beginning of loading, whereas further increase of the load decreases the slope of the curve reaching the minimum in the failure point. For the three parameters (end point the linear part, maximum reduced deviation of the diagram, tangent shear modulus at the failure point) characterizing the individual features of the presented stress-strain diagrams, approximating their dependences on the value of the reduced initial shear modulus are obtained. At the characteristic points of the deformation diagrams, boundary conditions are determined that can be used to find the parameters of the approximating functions. A condition is proposed for determination of the end point of the linear section on the experimental stress-strain curve, according to which the maximum deviation between the experimental and calculated (according to Hooke’s law) values of the shear stress in this section is no more than 1%, thus ensuring rather high accuracy of approximation on the linear section of the diagram. The results of this study are recommended to use when developing universal and relatively simple in structure approximating functions that take into account the characteristic properties of the experimental curves of deformation of polymer composite materials under in-plane shear of the sheet. The minimum set of experimental data is required to determine the parameters of these functions.
49
Fan, Zhi Geng, Chang Qing Chen, and Wen Jun Hu. "A Numerical Study on the Large Deformations of Polymer Foams with Spherical Pores." Advanced Materials Research 295-297 (July 2011): 1581–85. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1581.
Full textAbstract:
Cubic structures having spherical pores ranged as BCC and FCC lattices are constructed to simulate the microstructures of cellular polymers with various relative densities. The Mooney-Rivlin strain energy potential model is adopted to characterize the hyperelasticity of the constituent solid from which the foams are made. Finite element analysis on the influences of the polymer hyperelasticity upon the macroscopic mechanical properties of the foams is carried out. Numerical results show that there is no obvious buckling plateau segment in the uniaxial compressive stress-strain curves of the regular spherical cell models as most low density foams have. Moreover, it is found that the initial tangent modulus is a power function of the foam’s relative density, and the index is smaller than 2 for lower relative density models, bigger than 2 for moderate relative density models, and closed to 2 for higher relative density models.
50
Coffin, Douglas W. "Use of the efficiency factor to account for previous straining on the tensile behavior of paper." Nordic Pulp & Paper Research Journal 27, no. 2 (2012): 305–12. http://dx.doi.org/10.3183/npprj-2012-27-02-p305-312.
Full textAbstract:
Abstract The presented results suggest that the concept of efficiency factor previously used to demonstrate that changes in inter-fiber bonding in paper do not change the shape of the stress-strain curve can be extended to describe the changes that are observed in the tensile response of paper subjected to previous straining. It is found that the pre-yielding response for samples that have fully recovered from previous straining scales with changes in maximum tangent modulus. This deformation is mainly recoverable. When the scaling holds, one can extract a reasonable approximation of the initial recoverable deformation, which is separate from the plastic deformation. In essence, the efficiency factor acts as a stress magnification factor that easily can be incorporated into a constitutive equation. Tracking the change in efficiency factor with straining allows one to account for the loss of observed compliance for the entire range of recoverable deformation.