Experimental Investigation of Damage Characteristics in Steel Honeycomb Sandwich Beams

2010 ◽  
Vol 452-453 ◽  
pp. 557-560
Author(s):  
Jie Lu ◽  
Guang Ping Zou ◽  
Bao Jun Liu
Keyword(s):  
Failure Process ◽  
Sandwich Beams ◽  
Characteristic Parameters ◽  
Damage Initiation ◽  
Damage Characteristics ◽  
Damage And Failure ◽  
Honeycomb Sandwich ◽  
Bending Loads ◽  
Ae Counts ◽  
Good Agreement

In this work the fracture process of steel honeycomb sandwich beams has been investigate by situ acoustic emission(AE) technique. Pre-cracks were made both for L-direction and W-direction specimens subjected to out-plane three-points bending loads. Damage initiation sites were observed in the vicinity of the crack tip. A series of curves among the AE counts, AE hits, AE amplitude, AE energy and loading time were obtained. Damage characteristics were discussed based on the above parameters. The results indicate AE characteristic parameters can reflect the damage and failure process of specimens. A good agreement was found between the experimental and analytical results.

Experimental Investigation of Damage Characteristics in Steel Honeycomb Sandwich Beams

2011 ◽  
Vol 675-677 ◽  
pp. 685-688
Author(s):  
Jie Lu ◽  
Guang Ping Zou ◽  
Bao Jun Liu
Keyword(s):  
Failure Modes ◽  
Failure Process ◽  
Sandwich Beams ◽  
Damage Initiation ◽  
Damage Characteristics ◽  
Damage And Failure ◽  
Honeycomb Sandwich ◽  
Bending Loads ◽  
Good Agreement

Honeycomb sandwich structures are generally designed to carry flexural loads. However, mechanical properties can be influenced by accidental impacts, or service conditions. Thus a nondestructive detection testing is desired for them. In contrast to many conventional nondestructive evaluation (NDE) techniques, acoustic emission (AE) technique permits continuous damage inspection, classification and identification of failure modes in real time. In this work the fracture process of steel honeycomb sandwich beams has been investigated by in-situ AE technique. Pre-cracks were made both for L-direction and W-direction specimens subjected to three-points bending loads. Damage initiation sites were observed in the vicinity of the crack tip. A series of curves among the AE hits, AE amplitude, AE energy and loading time were obtained. Damage characteristics were discussed based on the above parameters. The results indicate AE characteristic parameters can reflect the damage and failure process of specimens. A good agreement was found between the experimental and analytical results.

Plastics Sandwich Beams under Bending Loads of Short Duration

1967 ◽  
Vol 9 (5) ◽  
pp. 355-361 ◽  
Author(s):  
R. M. Ogorkiewicz ◽  
A. A. M. Sayigh
Keyword(s):  
Polyvinyl Chloride ◽  
Short Duration ◽  
Stress Function ◽  
Local Stress ◽  
Sandwich Beams ◽  
Stress Concentrations ◽  
Four Point Bending ◽  
Bending Loads ◽  
Uniformly Distributed Loads ◽  
Good Agreement

Design of plastics sandwich structures calls for methods of predicting their deformation under load, which were studied with particular reference to beams under three- and four-point bending and under uniformly distributed loads. A preliminary series of tests established the stress-strain characteristics of p.v.c. (polyvinyl chloride) and polyurethane core and rigid p.v.c. skin materials. Using stress function solutions deflections and skin strains of different beams of these materials were then calculated and compared with experimental results obtained with beams made of the same combinations of materials. Good agreement was found for loads of short duration within the limits imposed by local stress concentrations.

Fatigue Life Prediction Investigation on Steel Honeycomb Sandwich Beams at High-Temperature

2011 ◽  
Vol 488-489 ◽  
pp. 698-701
Author(s):  
Jie Lu ◽  
Guang Ping Zou ◽  
Yang Cao
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Deformation Monitoring ◽  
Sandwich Beams ◽  
Three Point Bending ◽  
Time Deformation ◽  
Stiffness Reduction ◽  
Honeycomb Sandwich ◽  
Number Of Cycles ◽  
Good Agreement

The aim of this work is to investigate the fatigue behaviors of the steel honeycomb sandwich beams at 400°C through three point bending experiments. A stiffness reduction approach was adopted which was further based on the interpolation by the empirical functions of experimental results. For load control fatigue experiments, the evolution relations between number of cycles and displacement were obtained through real-time deformation monitoring of the specimens. A method based on exponential function fit was adopted in the further analysis, whose coefficients depended on the material properties, loading levels and high temperature conditions. This approach allowed us to predict the high temperature fatigue life of specimens while avoiding a large number of experiments. The results showed that experimental and prediction results were in a good agreement.

Numerical Simulation of Ring-Shape Rock Failure under Compressive Loading

2011 ◽  
Vol 378-379 ◽  
pp. 15-18
Author(s):  
Yong Bin Zhang ◽  
Zheng Zhao Liang ◽  
Shi Bin Tang ◽  
Jing Hui Jia
Keyword(s):  
Numerical Simulation ◽  
Fracture Process ◽  
Failure Modes ◽  
Failure Process ◽  
Compressive Loading ◽  
Orientation Angle ◽  
Crack Orientation ◽  
Ring Specimen ◽  
Ring Shape ◽  
Good Agreement

In this paper, a ring shaped numerical specimen is used to studying the failure process in brittle materials. The ring specimen is subjected to a compressive diametral load and contains two angled central cracks. Numerical modeling in this study is performed. It is shown that the obtained numerical results are in a very good agreement with the experiments. Effect of the crack orientation angle on the failure modes and loading-displace responses is discussed. In the range of 0°~40°, the fracture paths are curvilinear forms starting from the tip of pre-existing cracks and grow towards the loading points. For the crack orientation angle 90°, vertical fractures will split the specimen and the horizontal cracks do not influence the fracture process.

Damage Observation and Analysis of a Rock Brazilian Disc Using High-Speed DIC Method

2011 ◽  
Vol 70 ◽  
pp. 87-92 ◽  
Author(s):  
Shao Peng Ma ◽  
Dong Yan ◽  
Xian Wang ◽  
Yan Yan Cao
Keyword(s):  
Strain Field ◽  
Damage Evolution ◽  
High Speed ◽  
Failure Process ◽  
Tensile Load ◽  
Brazilian Test ◽  
Elastic Model ◽  
Strain Fields ◽  
Brazilian Disc ◽  
Damage And Failure

Observation of damage evolution is of great importance to the understanding of the failure process of rock materials. High-speed DIC system is constructed and used to observe the strain field evolution of the granodiorite disc in Brazilian test. The strain fields at different load levels are analyzed based on the stain abnormality indicator (SAI) which is the ratio of the strain measured in experiment to the strain from theoretical solution in an isotropy and elastic model. SAI could be used to indicate the damage in the specimen. The process of damage and failure of the specimen in Brazilian disc test is quantitatively analyzed and deeply discussed according to the strain fields and the statistics of SAI. Experimental results in this paper show that the failure process of the disc specimen in Brazilian test is not simple crack propagation under tensile load, but a complicated damage evolution procedure.

Collapse of Tubes Under Combined Bending and Axial Compression Loads

2018 ◽  
Author(s):  
Shan Jin ◽  
Shuai Yuan ◽  
Yong Bai
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Local Buckling ◽  
Practical Application ◽  
Buckling Modes ◽  
Combined Loads ◽  
Bending Loads ◽  
Good Agreement

In practical application, pipelines will inevitably experience bending and compression during manufacture, transportation and offshore installation. The mechanical behavior of tubes under combined axial compression and bending loads is investigated using experiments and finite element method in this paper. Tubes with D/t ratios in the range of 40 and 97 are adopted in the experiments. Then, the ultimate loads and the local buckling modes of tubes are studied. The commercial software ABAQUS is used to build FE models to simulate the load-shortening responses of tubes under combined loads. The results acquired from the ABAQUS simulation are compared with the ones from verification bending experiment, which are in good agreement with each other. The models in this paper are feasible to analyze the mechanical properties of tubes under combined axial compression and bending loads. The related results may be of interest to the manufacture engineers.

Fatigue Damage Monitoring of CFRP Elements by Thermographic Procedure under Bending Loads

2021 ◽  
Vol 873 ◽  
pp. 47-52
Author(s):  
Alessandra Pirinu ◽  
Francesco Panella
Keyword(s):  
Tensile Tests ◽  
Static Tests ◽  
Damage Initiation ◽  
Composite Damage ◽  
Damage Monitoring ◽  
Bending Loads ◽  
Ultrasonic Analysis ◽  
Local Compliance ◽  
Mechanical Tensile ◽  
Non Destructive

For structural health of mechanical structures, non-destructive detection and material defect characterization represent the main useful tools for mechanical decay prediction caused by local composite damage phenomena. In this work, internal delamination due to alternate bending were characterized in flat specimens, performing fatigue and static tests, coupled with thermographic, optical, and ultrasonic analysis for damage detection and evolution purposes. Damage to rupture behavior of CFRP material through mechanical tensile tests is performed on several samples and non-destructive inspection procedures are optimized during successive HCF tests to detect in real time local compliance variations and damage initiation. Thermographic continuous monitoring and occasional ultrasonic analysis are implemented to analyze composite anomalies during fatigue life and to elaborate a procedure for identification of delamination induced damage before failure. IRT and UT results are computed with MATLAB analysis for damage evaluation with strain and compliance data acquired during tests.

scholarly journals Experimental Study on the Evolution Law of Mesofissure in Full Tailing Cemented Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Yufan Feng ◽  
Guanghua Sun ◽  
Xuejian Liang ◽  
Chenyang Liu ◽  
Yue Wang
Keyword(s):  
Mechanical Properties ◽  
Pore Diameter ◽  
Failure Process ◽  
Hole Diameter ◽  
Fracture Density ◽  
Surface Porosity ◽  
Characteristic Parameters ◽  
Average Pore ◽  
Cemented Backfill ◽  
Lower Structure

To understand the mechanical properties of the backfill, to reveal the evolvement of micromechanical fissure of backfill, a uniaxial compression experiment was carried out for the full tailing cemented backfill. After loading, the microstructure of the specimens was observed by microscope and the pore characteristic parameters were analyzed. The results showed that the diameter of the initial damage hole of the backfill was mostly between 0 and 40 μm, the hole diameter increases gradually with the increase of pressure, and the hole diameter reached more than 5000 μm in the postpeak damage stage. The upper structure of the backfill specimen is compact while the lower structure is relatively loose. The cracks and interfaces between tailings particles and cement paste are mechanical weak surfaces, where the cracks are mainly generated and propagated. The tip of microfractures in the backfill is damaged by the influence of stress concentration. In the failure process, both surface porosity and fracture density decrease first and then increase, and the average pore diameter increases gradually. The results have guiding significance for the study of backfill mechanical properties and goaf filling design.

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