In-situ observation of microscopic damage in adhesively bonded CFRP joints under mode I and mode II loading

2019 ◽  
Vol 227 ◽  
pp. 111330 ◽  
Author(s):  
Sota Oshima ◽  
Akinori Yoshimura ◽  
Yoshiyasu Hirano ◽  
Toshio Ogasawara ◽  
Kwek-Tze Tan
Keyword(s):  
Mode I ◽  
Mode Ii ◽  
In Situ Observation ◽  
Adhesively Bonded ◽  
Microscopic Damage ◽  
Mode Ii Loading

The Effect of Temperature, Thickness, and Working Time on Adhesive Properties

2018 ◽  
Author(s):  
Nicholas Aerne ◽  
John P. Parmigiani
Keyword(s):  
Cantilever Beam ◽  
Design Process ◽  
Working Time ◽  
Effect Of Temperature ◽  
Control Group ◽  
Mode I ◽  
Mode Ii ◽  
Adhesive Properties ◽  
Loading Modes ◽  
Mode Ii Loading

The need for lightweight components and non-destructive fastening techniques has led to the growth of adhesive use in many industries. Modeling the behavior of adhesives in fastening joints can help in the design process to make an optimized joint. To optimize joints in the design process, the loading conditions, environmental conditions of service, thickness of bond, and bonding procedures all need to be refined for the adhesive of interest. However, in available technical data sheets of adhesives provided by manufactures there is a gap in what is sufficient to accurately model and predict the behavior of real-world adhesive conditions. This body of research presents the results of the effects of temperature, thickness, and working time on adhesive properties. These effects can be observed with test specimens from the loading modes of interest. The loading modes of interest are mode I and mode II loading for the current study. The specimen for mode I loading is the Double Cantilever Beam, and for mode II loading is the Shear Loaded Dual Cantilever Beam. The effect of temperature will be tested by testing each specimen at −20°C, 20°C, and 40°C. Two bond thicknesses for adhesive thickness effects were tested. The working time had a control group bonded in the recommended working time and an expired working time group where the specimens were not joined until 10 minutes had passed from the recommended working time. Triplicates of each specimen at the respective conditions were tested. The adhesive selected for this research was Plexus MA832. The results of the experiment show that adhesive factors such as temperature, thickness, and working time can have degrading effects on adhesive performance in mode I and mode II.

Buckling Evolution of Microelectromechanical Structures

1998 ◽  
Vol 518 ◽  
Author(s):  
Xin Zhang ◽  
Tong-Yi Zhang ◽  
Yitshak Zohar
Keyword(s):  
Theoretical Analysis ◽  
Local Buckling ◽  
Experimental Results ◽  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Sacrificial Layers

AbstractThis study reports in-situ observations of the buckling evolution of microelectromechanical structures during etching of their underneath sacrificial layers. As the etching went on, the buckling pattern evolved from mode I, the sinusoidal half-waves, to mode II, the constrained sinusoidal half-waves, to mode III, the conventional mode, and finally to mode IV, the blister- like local buckling. Closed formulae were derived from theoretical analysis, and the experimental results agreed well with the theoretical ones.

Microstructural Effects on Fracture Toughness of Polycrystalline Ceramics in Combined Mode I and Mode II Loading

1989 ◽  
Vol 111 (1) ◽  
pp. 174-180 ◽  
Author(s):  
D. Singh ◽  
D. K. Shetty
Keyword(s):  
Fracture Toughness ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Transgranular Fracture ◽  
Pure Mode ◽  
Polycrystalline Alumina ◽  
Polycrystalline Ceramics ◽  
Mode Ii Loading ◽  
Combined Mode

Fracture toughness of polycrystalline alumina and ceria partially stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion were the main sources of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.

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