scholarly journals Experimental and Numerical Study on the Compressive Failure of Composite Laminates with Fiber Waviness Defects

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3204
Author(s):  
Yuequan Wang ◽  
Shuhua Zhu ◽  
Hongshuang Li ◽  
Long Zhou ◽  
Wentao Yi
Keyword(s):  
Numerical Simulation ◽  
Failure Load ◽  
Numerical Study ◽  
Experimental Testing ◽  
Failure Process ◽  
Experimental Results ◽  
Compressive Failure ◽  
Fiber Waviness ◽  
Acceptance Criterion ◽  
The Impact

Fiber waviness defects are found in the inner surface of the hat-shaped stringers manufactured by a process system. In order to establish the acceptance criterion for the stringers with the fiber waviness defects, experimental testing and numerical simulation were carried out in this study. Specially induced fiber waviness defects of four pre-defined severity levels were manufactured and tested. A maximum of a 58.1% drop in compressive failure load is observed for the most severe level in the experimental results. A finite element model with progressive damage method and cohesive zone technique was developed to simulate the failure process and the impact of fiber waviness defects. The numerical simulation results of compressive failure load have a good agreement with experimental results qualitatively and quantitatively. In addition, two simple parameters, i.e., aspect ratio A/H and the number of plies with fiber waviness, are proposed to characterize the influence of the fiber waviness on the compressive failure load for the purpose of fast engineering quality checks.

scholarly journals Breccia interlayer effects on steam-assisted gravity drainage performance: experimental and numerical study

2021 ◽  
Author(s):  
Qichen Zhang ◽  
Xiaodong Kang ◽  
Huiqing Liu ◽  
Xiaohu Dong ◽  
Jian Wang
Keyword(s):  
Numerical Simulation ◽  
Oil Recovery ◽  
Oil Sands ◽  
Numerical Study ◽  
Middle Part ◽  
Experimental Results ◽  
Production Performance ◽  
Peak Oil ◽  
Steam Chamber ◽  
The Impact

AbstractCurrently, the reservoir heterogeneity is a serious challenge for developing oil sands with SAGD method. Nexen’s Long Lake SAGD project reported that breccia interlayer was widely distributed in lower and middle part of reservoir, impeding the steam chamber expansion and heated oil drainage. In this paper, two physical experiments were conducted to study the impact of breccia interlayer on development of steam chamber and production performance. Then, a laboratory scale numerical simulation model was established and a history match was conducted based on the 3D experimental results. Finally, the sensitivity analysis of thickness and permeability of breccia layer was performed. The influence mechanism of breccia layer on SAGD performance was analyzed by comparing the temperature profile of steam chamber and production dynamics. The experimental results indicate that the existence of breccia interlayer causes a thinner steam chamber profile and longer time to reach the peak oil rate. And, the ultimate oil recovery reduced 15.8% due to much oil stuck in breccia interlayer areas. The numerical simulation results show that a lower permeability in breccia layer area has a serious adverse impact on oil recovery if the thickness of breccia layer is larger, whereas the effect of permeability on SAGD performance is limited when the breccia layer is thinner. Besides, a thicker breccia layer can increase the time required to reach the peak oil rate, but has a little impact on the ultimate oil recovery.

Numerical Study on Influence of Joint Characters on Rock Mechanical Parameters

2011 ◽  
Vol 201-203 ◽  
pp. 2909-2912
Author(s):  
Yan Feng Feng ◽  
Tian Hong Yang ◽  
Hua Wei ◽  
Hua Guo Gao ◽  
Jiu Hong Wei
Keyword(s):  
Rock Mass ◽  
Compression Strength ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Deformation Modulus ◽  
Rock Joints ◽  
Structured Surfaces ◽  
Trace Length ◽  
The Impact

Rock mass is the syntheses composed of kinds of structure and structured surfaces. The joint characters is influencing and controlling the rock mass strength, deformation characteristics and rock mass engineering instability failure in a great degree. Through using the RFPA2D software, which is a kind of material failure process analysis numerical methods based on finite element stress analysis and statistical damage theory, the uniaxial compression tests on numerical model are carried, the impact of the trace length of rock joints and the fault throws on rock mechanics parameters are studied. The results showed that with the gradual increase of trace length,compression strength decreased gradually and its rate of variation getting smaller and smaller, the deformation modulus decreased but the rate of variation larger and larger; with the fault throws increasing, the compression strength first increases and then decreases, when the fault throw is equal to the trace length, the deformation modulus is the largest. When the joint trace length is less than the fault throw, the rate of the deformation modulus is greater than that of trace length, but the deformation modulus was not of regular change.

The Impact Analysis of Ground Stability Caused by Exploiting Underground Coal

2011 ◽  
Vol 243-249 ◽  
pp. 3147-3150
Author(s):  
Shu Xian Liu ◽  
Xiao Gang Wei ◽  
Shu Hui Liu ◽  
Li Ping Lv
Keyword(s):  
Numerical Simulation ◽  
Coal Mining ◽  
Impact Analysis ◽  
Shear Failure ◽  
Failure Process ◽  
Wall Rock ◽  
Strong Impact ◽  
Element Analysis ◽  
Deformation And Failure ◽  
The Impact

Disaster caused by exploiting underground coal is due to original mechanical equilibrium of underground rock has been destroyed when underground coal is exploited. And Stress redistribution and stress concentration of wall rock in the goaf happened too. As many complex factors exist such as complex structures of ground, multivariate stope boundary conditions, many stochastic mining factors and so on, it is difficult to evaluate the damage of the geological environment caused the excavation by surrounding underground coal accurately. Besides that, the coexistence of continuous and discontinuous of deformation and failure of wall rock make a strong impact on the ground, and the co-exist of tension, compression and shear failure also pay a great deal contribution to the destroy. Due to the mechanical property and deformation mechanism of goaf are complex , changeable, nonlinear and probabilistic, which changes with in space and time dynamically, it can not be studied analytically by the classical mathematical model and the theory of mechanics computation. Through finite element analysis software ABAQUS, a numerical simulation of the process of underground coal mining have been made. After make a research of the simulation process, it shows the change process of stress environment of wall rock and deformation and failure process of rock mass during the process of coal mining. The numerical simulation of the process can provide theoretical basis and technical support to the protection and reinforcement of laneway the process of coal excavation. Besides that, it also provides a scientific basis and has a great significance to reasonable Excavation and control of mind-out area.

scholarly journals Failure Behavior of F Shape Non-Persistent Joint under Experimental and Numerical Uniaxial Compression Test

2021 ◽  
Author(s):  
vahab sarfarazi ◽  
kaveh asgari ◽  
meisam zarei
Keyword(s):  
Numerical Simulation ◽  
Compression Test ◽  
Experimental Testing ◽  
Failure Process ◽  
Particle Flow Code ◽  
Failure Behavior ◽  
Uniaxial Compression Test ◽  
Joint Angles ◽  
Large Joint ◽  
Load Rate

Abstract Experimental and discrete element approaches were used to examine the effects of F shape non-persistent joints on the failure behaviour of concrete under uniaxial compressive test. concrete specimens with dimensions of 200 mm×200 mm×50 mm were provided. Within the specimen, F shape non-persistent joint consisting three joints were provided. The large joint length was 6 cm, and the length of two small joints were 2cm. Vertical distance betwenn two small joints change from 1.5 cm to 4.5 cm with increment of 1.5 cm. In constant joint lengths, the angle of large joint change from 0 to 90 with increments of 30. Totally 12 different models were tested under compression test. The axial load rate on the model was 0.05 mm/min. Cuncurrent with experimental tests, numerical simulation (Particle flow code in two dimension) were performed on the models containing F shape non-persistent joint. Distance between small joints and joint angles were similar to experimental one. the results indicated that the failure process was mostly governed by both of the Distance between small joints and joint angles. The compressive strengths of the samples were related to the fracture pattern and failure mechanism of the discontinuities. Furthermore it was shown that the compressive behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint angle. In the first There were only a few AE hits in the initial stage of loading, then AE hits rapidly grow before the applied stress reached its peak. Furthermore, a large number of AE hits accompanied every stress drop. Finally, the failure pattern and failure strength are similar in both approaches i.e. the experimental testing and the numerical simulation approaches.

Numerical study of dynamic behavior of foams subjected to high- to hyper-velocity impact

2019 ◽  
Author(s):  
Xiaotian Zhang ◽  
Ruiqing Wang ◽  
Q.M. Li
Keyword(s):  
Dynamic Behavior ◽  
Impact Velocity ◽  
Foam Cell ◽  
Numerical Study ◽  
Failure Process ◽  
Failure Mechanisms ◽  
Hypervelocity Impact ◽  
Deformation And Failure ◽  
Set Up ◽  
The Impact

Abstract Hypervelocity tests and numerical studies have been reported in the literature for aluminum foam to show its potential applications in spacecraft shielding against space debris based on “shielding set-up”. Meanwhile the “forward impact” set-up has been widely reported in the literature to study the dynamic behavior of the foam materials in the range of low to intermediate impact velocities. This paper extends the forward impact to high- and hyper-velocity impacts to understand the dynamic deformation and failure mechanisms based on numerical simulation. The focused impact velocity range is from about 1km/s to 6km/s. The cell-based numerical model of the foam material is used along with the Smoothed Particle Hydrodynamics (SPH) method to simulate the deformation and the failure process. The failure of the foam materials in the range of intermediate to high impact velocities is related to the plastic yielding and crushing of the foam cell, while that in the hypervelocity impact regime is related to the cell material erosion. Dynamic effects in different impact velocity ranges also lead to shock and strain-rate effects. Understanding of the dependence of the deformation/failure mechanisms on the impact velocity helps to determine the application of foam materials in the relevant range of impact velocities.

Numerical and experimental investigations on the effect of target thickness and solution treatment on the ballistic behaviour of AA7075 thick plates

2021 ◽  
pp. 095440622110389
Author(s):  
R Praveen ◽  
SR Koteswara Rao ◽  
R Damodaram ◽  
S Suresh Kumar
Keyword(s):  
Numerical Simulation ◽  
Plate Thickness ◽  
Solution Treatment ◽  
Target Thickness ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Depth Of Penetration ◽  
Solution Treated ◽  
The Impact ◽  
T651 Condition

The influence of target thickness and solution treatment on the ballistic behaviour of AA7075 targets has been investigated by both numerical and experimental methods. In numerical simulation, the target thickness was varied from 19 to 26 mm and an Ogive nose shaped projectile of 7.62 mm diameter with inlet velocities ranging between 800–875 m/s was considered. In order to justify the numerical observations, high velocity ballistic experiments were conducted on AA7075-T651 and the solution treated plates of various thicknesses (12, 16, 18, 20, 22 and 25 mm). For this experimental study, a deformable form projectile with dimensions of 7.62 × 51 mm and an inlet velocity of 850 ± 20 m/s was used. Microstructures of ballistic test samples were analysed using an optical microscope. Numerical analysis using ABAQUS predicted the minimum thickness required to resist complete penetration to be 20 mm in the case of AA7075 plates in the T651 condition, while experimental results showed it to be 21 mm. In the case of AA7075 solution treated plates, numerical simulation analysis predicted the minimum required plate thickness to resist complete penetration to be 24 mm, while the experimental results showed it to be 23 mm. Post ballistic microstructure analysis revealed that there was no change in the microstructure in the AA7075-T651 condition plates. Solution treated plates showed deformation of grains nearer to the impact region with the formation of adiabatic shear bands. In the case of the T651 plate, the mode of fracture was brittle, resulting in splinters, whereas it was petalling in the case of the solution-treated plates. The numerically predicted depth of penetration on both targets was reasonably close to experimental results with an average of 4% error.

Numerical Study of the Impact of Constitutive Modelling on the Evolution of Necking in the Case of a Tensile Test on C68 Grade Steel

2014 ◽  
Vol 611-612 ◽  
pp. 521-528 ◽  
Author(s):  
Laurent Tabourot ◽  
Pascale Balland ◽  
Ndéye Awa Sene ◽  
Mathieu Vautrot ◽  
Nesrine Ksiksi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Test ◽  
Numerical Study ◽  
Constitutive Modelling ◽  
Microscopic Level ◽  
Point Of View ◽  
Physical Phenomena ◽  
The Impact ◽  
Over Time ◽  
Grade Steel

This article deals with numerical simulation of necking. It draws the attention onto the importance of the description of strain-hardening and the effects on the evolution of necking. In order to compare necking evolution in relation with different plasticity models, a tracking procedure which consists in determining the evolution over time of discharged volumes of the sample is adopted. Models that take into account physical phenomena at the microscopic level and especially the heterogeneities of materials from a mechanical point of view seem well suited to fit experimental evidence connected to necking.

scholarly journals Experimental and Numerical Study on Mechanical Properties and Deformation Behavior of Beishan Granite considering Heterogeneity

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Z. H. Wang ◽  
Y. L. Tan ◽  
S. M. Li ◽  
T. Z. Wang ◽  
X. C. Wu
Keyword(s):  
Numerical Simulation ◽  
Mechanical Response ◽  
Numerical Study ◽  
Failure Process ◽  
Confining Pressure ◽  
Sample Volume ◽  
Mechanical Tests ◽  
Peak Strength ◽  
Research Subjects ◽  
Beishan Granite

Disposal of high-level radioactive waste (HLW) deep underground is one of the most challenging research subjects in rock engineering. In China, Beishan granite is usually chosen as host rock for the construction of the HLW repository. In this study, mechanical tests are conducted on Beishan granite and the stress-strain state during the complete failure process is analyzed by numerical simulation. The results show that the tensile strength and uniaxial compressive strength of Beishan granite are 8.66 and 162.9 MPa, respectively. Dilatancy appears when the stress reaches about 81% of the peak strength. Heterogeneity is introduced by Weibull distribution in numerical simulation. With the increase of homogenization degree, the degraded elements are more easily to concentrate locally. Based on experimental and numerical simulation results, it is noticeable that the sample volume is basically in the state of compaction before reaching the peak strength. The elements are more likely to show expansion, and the splitting failure dominates the destroy mode when the confining pressure is relatively low. With increasing confining pressure, more and more degraded elements are concentrated in the shear band, which develops from the surface to the interior of the sample during loading. Therefore, the granite shows ductile mechanical response characteristics when the confining pressure is relatively high. The results are instructive for the construction of the repository.

scholarly journals The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2959
Author(s):  
Eckart Kunze ◽  
Siegfried Galkin ◽  
Robert Böhm ◽  
Maik Gude ◽  
Luise Kärger
Keyword(s):  
Mechanical Properties ◽  
Experimental Results ◽  
Analytical Models ◽  
Failure Behavior ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Fiber Waviness ◽  
Reinforced Plastics ◽  
The Impact ◽  
Local Fiber

Unidirectional non-crimp fabrics (UD-NCF) are often used to exploit the lightweight potential of continuous fiber reinforced plastics (CoFRP). During the draping process, the UD-NCF fabric can undergo large deformations that alter the local fiber orientation, the local fiber volume content (FVC) and create local fiber waviness. Especially the FVC is affected and has a large impact on the mechanical properties. This impact, resulting from different deformation modes during draping, is in general not considered in composite design processes. To analyze the impact of different draping effects on the mechanical properties and the failure behavior of UD-NCF composites, experimental results of reference laminates are compared to the results of laminates with specifically induced draping effects, such as non-constant FVC and fiber waviness. Furthermore, an analytical model to predict the failure strengths of UD laminates with in-plane waviness is introduced. The resulting stiffness and strength values for different FVC or amplitude to wavelength configurations are presented and discussed. In addition, failure envelopes based on the PUCK failure criterion for each draping effect are derived, which show a clear specific impact on the mechanical properties. The findings suggest that each draping effect leads to a “new fabric” type. Additionally, analytical models are introduced and the experimental results are compared to the predictions. Results indicate that the models provide reliable predictions for each draping effect. Recommendations regarding necessary tests to consider each draping effect are presented. As a further prospect the resulting stiffness and strength values for each draping effect can be used for a more accurate prediction of the structural performance of CoFRP parts.

Identification of damage stages in bolted metallic joints for different joint geometries and tightening torques using statistical analysis

2019 ◽  
Vol 23 (5) ◽  
pp. 911-923 ◽  
Author(s):  
Amr Abd-Elhady ◽  
Ahmed Abu-Sinna ◽  
Mahmoud Atta ◽  
Hossam El-Din M Sallam
Keyword(s):  
Analysis Of Variance ◽  
Failure Load ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Experimental Results ◽  
Bolted Joints ◽  
Tightening Torque ◽  
Joint Geometry ◽  
Joint Width ◽  
The Impact

The main parameters controlling the structural behavior of bolted joints are the tightening torque ( T) and the joint geometry such as the edge distance ( e) to the bolt hole diameter ( D) ratio ( e/ D) and the joint width ( W) to the hole diameter ratio ( W/ D). In the first part of this study, the effects of W/ D and T, with a constant value of e/ D ( e/ D = 3), have been studied experimentally. Three values of W/ D (2.25, 3, and 3.75) with six values of T (0, 10, 15, 20, 25, and 30 N m) have been chosen to construct 18 assemblies. Experimental results highlighted the impact of W/ D, and T, on the different failure stages of bolted double-lap metallic joints. In the second part of this study, analysis of variance has been adopted to analyze the effects of T and W/ D in addition to the effect of e/ D which has been studied previously by the authors. The present experimental results showed that the value of applied load at which the sticking failure occurred increased by increasing the tightening torque up to T = 25 N m for all values of W/ D. However, the other stages of failure were slightly affected by the value of T. The results obtained from the analysis of variance identified that there is no clear effect of W/ D and e/ D on the sticking failure load. However, their effects are markedly clear for other stages of failure.

Sign in / Sign up

Export Citation Format

Share Document