scholarly journals Static and Fatigue Failures of Adhesively Bonded Laminate Joints in Moist Environments

2011 ◽  
Vol 20 (8) ◽  
pp. 1217-1242 ◽  
Author(s):  
K. B. Katnam ◽  
A. D. Crocombe ◽  
H. Sugiman ◽  
H. Khoramishad ◽  
I. A. Ashcroft
Keyword(s):  
Cohesive Zone ◽  
Experimental Tests ◽  
Static Fatigue ◽  
Test Results ◽  
Adhesively Bonded ◽  
Aerospace Applications ◽  
Numerical Predictions ◽  
Fatigue Failures ◽  
Good Agreement

Advanced structural adhesives are now an important joining technique in automobile and aerospace applications. The perceived uncertainty in the long-term structural performance of bonded members when subjected to static/fatigue loads in aggressive environments is probably restricting an even more widespread use of this joining technology. In this article, the effect of moisture on the static and fatigue resistances of adhesively bonded laminate joints was investigated. Experimental tests were performed on both aged and unaged adhesively bonded laminate joints for static and fatigue responses. Further, using a cohesive zone approach for the adhesive bondlines, a combined diffusion–stress analysis was developed to predict the progressive damage observed in the joints tested experimentally. The numerical predictions were found to be in good agreement with the experimental test results.

Creep of the copper canister in the Swedish program

2006 ◽  
Vol 932 ◽  
Author(s):  
William H Bowyer
Keyword(s):  
Nuclear Waste ◽  
Strengthening Mechanism ◽  
Test Results ◽  
Short Life ◽  
Iron Load ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Life Predictions ◽  
Good Agreement

ABSTRACTThe Swedish programme for disposal of high level nuclear waste includes the development of a container which comprises a cast iron load bearing canister contained in a 50 mm thick copper corrosionshield.The temperature of the outside of the canister is likely be up to 100°C, and repository processes may lead to long term loads of up to 50MPa. Creep of the copper is therefore an issue. SKB (The Swedish Nuclear Fuel and Waste Management Co.) have been conducted tests on three materials, OF copper containing 10ppm sulphur (OF1), OF copper containing 6ppm sulphur (OF2) and OF copper containing 6ppm sulphur and 50ppm phosphorus (OFP). In order to improve confidence in extrapolation of test results to practical temperatures and stresses, it is desirable to support the extrapolation procedures with a physical model.Life predictions made using the Frost and Ashby model [5] together with a simplification of the Cocksand Ashby model [6] provide good agreement with published experimental data for OF2 and OFPmaterials. Extrapolation of this data using the model leads to life predictions of 12,000 years for the OF2material and 120,000 years for OFP material. The prediction for OFP depends on an assumption that an observed strengthening mechanism conferred by phosphorus at high stresses and temperatures, is equally as effective under repository conditions.OF1 material fails after a relatively short life and by a different mechanism to OF2 and OFP. The changein mechanism may be explained, using the model [6], for cases where segregating species reduce surface energy of grain boundary voids. It is suggested that in this case the segregating species is sulphur.

Low Velocity Impact of a Viscoelastic Beam

1982 ◽  
Vol 104 (2) ◽  
pp. 210-215
Author(s):  
R. E. Llorens ◽  
E. J. McQuillen
Keyword(s):  
Composite Laminates ◽  
Low Velocity Impact ◽  
Viscoelastic Beam ◽  
Test Results ◽  
Transverse Impact ◽  
Low Velocity ◽  
Euler Beam ◽  
Numerical Predictions ◽  
Linear Viscoelastic ◽  
Good Agreement

A theoretical solution for the response of a viscoelastic beam to off-center low speed transverse impact is presented. The flexural model adopted for investigation consists of a uniform Bernoulli-Euler beam whose behavior has been generalized to include a linear viscoelastic constitutive relation for each element of the beam. Further, the beam and rigid impactor are assumed to remain in contact during the resulting motion and a consistent set of initial displacement and velocity distributions is adopted for the beam. The solution method utilizes two Laplace transforms, i.e., one with respect to space and the other with respect to time. Comparison of the numerical predictions of the theoretical model with central impact test results on graphite-epoxy composite laminates indicates a good agreement between theory and experiment.

scholarly journals Advanced Modeling and Simulation of Rockfall Attenuator Barriers Via Partitioned DEM-FEM Coupling

2021 ◽  
Vol 7 ◽  
Author(s):  
Klaus Bernd Sautter ◽  
Helene Hofmann ◽  
Corinna Wendeler ◽  
Peter Wilson ◽  
Philipp Bucher ◽  
...  
Keyword(s):  
Modeling And Simulation ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Simulation Method ◽  
Design Decision ◽  
Test Results ◽  
The Finite Element Method ◽  
Shape Sphere ◽  
Good Agreement ◽  
Element Method

Attenuator barriers, in contrast to conventional safety nets, tend to smoothly guide impacting rocks instead of absorbing large amounts of strain energy arresting them. It has been shown that the rock’s rotation plays an important role in the bearing capacity of these systems. Although experimental tests have to be conducted to gain a detailed insight into the behavior of both the structures and the rock itself, these tests are usually costly, time-consuming, and offer limited generalizability to other structure/environment combinations. Thus, in order to support the engineer’s design decision, reinforce test results and confidently predict barrier performance beyond experimental configurations this work describes an appropriate numerical modeling and simulation method of this coupled problem. For this purpose, the Discrete Element Method (DEM) and the Finite Element Method (FEM) are coupled in an open-source multi-physics code. In order to flexibly model rocks of any shape, sphere clusters are used which employ simple and efficient contact algorithms despite arbitrarily complicated shapes. A general summary of the FEM formulation is presented as well as detailed derivations of finite elements particularly pertinent to rockfall simulations. The presented modeling and coupling method is validated against experimental testing conducted by the company Geobrugg. Good agreement is achieved between the simulated and experimental results, demonstrating the successful practical application of the proposed method.

scholarly journals Experimental Field Tests and Finite Element Analyses for Rock Cracking Using the Expansion of Vermiculite Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Chi-hyung Ahn ◽  
Jong Wan Hu
Keyword(s):  
Finite Element ◽  
Field Tests ◽  
Experimental Tests ◽  
Heating Time ◽  
Test Results ◽  
Experimental Field ◽  
Expansion Pressure ◽  
Circular Holes ◽  
Granite Rocks ◽  
Good Agreement

In the previous research, laboratory tests were performed in order to measure the expansion of vermiculite upon heating and to convert it into expansion pressure. Based on these test results, this study mainly focuses on experimental field tests conducted to verify that expansion pressure obtained by heating vermiculite materials is enough to break massive and hard granite rock with an intention to excavate the tunnel. Hexahedral granite specimens with a circular hole perforated in the center were constructed for the experimental tests. The circular holes were filled with vermiculite plus thermal conduction and then heated using the cartridge heater. As a result, all of hexahedral granite specimens had cracks in the surface after 700-second thermal heating and were finally spilt into two pieces completely. The specimen of larger size only requires more heating time and expansion pressure. The material properties of granite rocks, which were obtained from the experimental tests, were utilized to produce finite element models used for numerical analyses. The analysis results show good agreement with the experimental results in terms of initial cracking, propagation direction, and expansion pressure.

Analysis of bearing failures in a typical high-power marine gearbox

2018 ◽  
Vol 70 (1) ◽  
pp. 33-41
Author(s):  
Haigang Gu ◽  
Guang Feng ◽  
Yonggang Lin ◽  
Chaozhu Wang
Keyword(s):  
Theoretical Analysis ◽  
Roller Bearing ◽  
Fretting Fatigue ◽  
Test Results ◽  
Content Type ◽  
Bearing Failures ◽  
Manufacturing Errors ◽  
Cylindrical Roller ◽  
Fatigue Failures ◽  
Good Agreement

Purpose This paper aims to analyze fatigue failures of a typical marine gearbox under harsh ocean conditions, and these failures are reasonably attributed to the bearing fretting fatigue damages. Design/methodology/approach Two typical FAG cylindrical roller bearings mounted on this marine gearbox are particularly used for analysis, as they are most vulnerable to these failures. A series of simulations have also been conducted to verify the analysis results and failure reasons by reproducing the fretting fatigue damages for the same shaft-bearing system under the same manufacturing error conditions. Findings The analysis results indicate that manufacturing errors are the most possible reasons for the bearing failures, and these errors have more effects on the FAG cylindrical roller bearing as compared to other bearings mounted on the same shaft system. The simulations results are in good agreement with the theoretical analysis results and test results and hence validate that manufacturing errors are the dominant reasons for bearing fretting fatigue damages in this typical marine gearbox. Originality/value Fatigue failures of a typical marine gearbox. Manufacturing errors are the most possible reasons for the bearing failures. A series of simulations have been conducted to verify the analysis results and failure reasons. The simulations results are in good agreement with the theoretical analysis results and test results.

On Second-Order Roll Motions of Ships

2003 ◽  
Author(s):  
Yonghui Liu
Keyword(s):  
Second Order ◽  
Roll Motion ◽  
Frequency Domain Method ◽  
Test Results ◽  
Order Difference ◽  
Numerical Predictions ◽  
Offshore Engineering ◽  
Random Seas ◽  
Ship Roll ◽  
Good Agreement

More and more vessels for offshore engineering applications have a roll period beyond 20 seconds in order to avoid the wave frequency excitations on the roll motion. That is particularly true for the latest drilling vessels. However, this will lead to an unexpected second-order roll motion of the ships. This paper will present a new methodology to evaluate the second-order roll motions of the ships in random seas. The higher-order boundary element method (HOBEM) has been utilized to generate the second order difference-frequency roll excitations on the ships and the second-order ship roll motions were predicted by a frequency-domain method. A series of model tests have been conducted and the test results have a good agreement with the numerical predictions. Therefore, this new method has been verified and validated.

scholarly journals Latitude Determination and Error Analysis for Stationary SINS in Unknow-Position Condition

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2558
Author(s):  
Suier Wang ◽  
Gongliu Yang ◽  
Wei Chen ◽  
Lifen Wang
Keyword(s):  
Navigation System ◽  
Estimation Method ◽  
Experimental Tests ◽  
The Self ◽  
Measurement Unit ◽  
Test Results ◽  
Bias Estimation ◽  
Short Time ◽  
The Relationship

The initial geographic latitude information is the key to the self-alignment of the strapdown inertial navigation system (SINS), but how to determine the latitude when the latitude cannot be obtained directly or in a short time? The latitude determination (LD) methods are introduced, including magnitude method, geometric method, and analytical methods 1 and 2, to solve this situation only by the output of the SINS itself. Simulation and experimental test results validate the efficiency of these LD methods. In order to improve the accuracy of the LD, the error of the LD method is derived through comparative analysis. Based on the relationship between LD error and inertial measurement unit (IMU) bias. Partial bias estimation method is introduced and executed during latitude determination. After compensating the estimated IMU bias, the accuracy of the LD will be further improved. Latitude errors are also affected by the latitude where SINS is located. Comprehensive simulation and experimental tests verify the effectiveness of the method. The IMU determined latitude can not only be used to achieve the self-alignment of the SINS, but also to correct the navigation latitude of the long-term SINS, thereby improving the autonomy and positioning accuracy of the navigation system.

Parents' long-term adjustment to the genetic test results of minors at risk for Long QT Syndrome

2004 ◽  
Author(s):  
K. S. W. H. Hendriks ◽  
F. J. M. Grosfeld ◽  
A. A. M. Wilde ◽  
J. van den Bout ◽  
I. M. van Langen ◽  
...  
Keyword(s):  
At Risk ◽  
Long Qt Syndrome ◽  
Genetic Test ◽  
Test Results ◽  
Long Qt ◽  
Genetic Test Results ◽  
Qt Syndrome

The Implementation Of Make A-Match Model In Social Science Learning To Improve Student Learning Outcomes In Class IV SDN 115 Manado

2019 ◽  
Vol Volume 2 Nomor 2 ◽  
Keyword(s):  
Social Science ◽  
Learning Outcomes ◽  
Teaching And Learning ◽  
Science Learning ◽  
Design Activity ◽  
Test Results ◽  
Match Model ◽  
Fourth Grade Students ◽  
Improve Student Learning

There is a tendency in the education field today to return to the idea that children will learn better if the environment is created naturally. Learning will be more meaningful if children "experience" themselves what they are learning, not 'knowing' it. Target-oriented learning of material mastery proves to be successful in short-term 'remembering' competitions, but fails to equip children to solve problems in long-term life. The problems that would to be studied in this study are: (a) how is the improvement of Social Science learning outcomes by applying the Make A-Match Model to it? (b) how does the Make A-Match Model apply towards the learning motivation? The objectives of this study are: (a) want to know the improvement in Social Science learning achievement after the implemetation of the Make A-Match Model. (b) want to know the effect of Make A-Match Model towards students’ motivation of the subject after it is applied. This research is used two rounds of action research. In each round consists of four stages, namely: design, activity and observation, reflection and revision. The target of this research is the fourth grade students of Mongodow. The data obtained in the form of formative test results, observation sheets of teaching and learning activities. From the results of analysts obtained student achievement has increased from cycle I to cycle II namely, cycle I (65%), cycle II (83%). The conclusion of this research is the Make A-Match Model of Social Science learning could positively influence the motivation of learning of central students, and this learning model could be used as an alternative to Social Science learning.

Long Term Field Test Results of Experimental EPDM and PUF Roofing

1990 ◽  
Author(s):  
David M. Bailey ◽  
Stuart D. Foltz ◽  
Myer J. Rosenfield
Keyword(s):  
Field Test ◽  
Test Results ◽  
Term Field
Sign in / Sign up

Export Citation Format

Share Document