Effects of adhesive parameters on out-of-plane compression and compression fatigue response of adhesively bonded sandwiches with pyramidal core

2018 ◽  
Vol 206 ◽  
pp. 131-139 ◽  
Author(s):  
Zhi-jia Zhang ◽  
Qian-cheng Zhang ◽  
Xiao-bo Shi ◽  
Wei-jin Zhang ◽  
Feng Jin
Keyword(s):  
Adhesively Bonded ◽  
Out Of Plane ◽  
Plane Compression

scholarly journals The Out-of-Plane Compression Behavior of Cross-Ply AS4/PEEK Thermoplastic Composite Laminates at High Strain Rates

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2312 ◽  
Author(s):  
Huiran Zou ◽  
Weilong Yin ◽  
Chaocan Cai ◽  
Bing Wang ◽  
Ankang Liu ◽  
...  
Keyword(s):  
Composite Laminates ◽  
High Strain ◽  
Damage Mechanism ◽  
Strain Rates ◽  
Failure Condition ◽  
High Strain Rates ◽  
Peek Composite ◽  
Out Of Plane ◽  
Complete Failure ◽  
Plane Compression

The dynamic mechanical behavior of thermoplastic composites over a wide range of strain rates has become an important research topic for extreme environmental survivability in the fields of military protection, aircraft safety, and aerospace engineering. However, the dynamic compression response in the out-of-plane direction, which is one of the most important loading conditions resulting in the damage of composite materials, has not been investigated thoroughly when compared to in-plane compression and tensile behavior under high strain rates. Thus, we used split Hopkinson pressure bar (SHPB) tests to conduct the out-of-plane compression test of cross-ply carbon fiber-reinforced polyetheretherketone (AS4/PEEK) composite laminates. Afterward, the damage mechanism under different strain rates was characterized by the macrostructure morphologies and scanning electron microscope micrographs. Two major cases of the incomplete failure condition and complete failure condition were discussed. Dynamic stress-strain curves expound the strain rates dependencies of elastic modulus, failure strength, and failure strain. An obvious spring-back process could be observed under incomplete failure tests. For the complete failure tests, secondary loading could be observed by reconstructing and comparing the dynamic response history. Lastly, various failure modes that occurred in different loading strain rates illustrate that the damage mechanism also shows obvious strain rate sensitivity.

scholarly journals Mechanical bistability enabled by ectodermal compression facilitates Drosophila mesoderm invagination

2021 ◽  
Author(s):  
Hanqing Guo ◽  
Michael Swan ◽  
Shicheng Huang ◽  
Bing He
Keyword(s):  
Myosin Ii ◽  
Cell Sheet ◽  
Apical Surface ◽  
Apical Constriction ◽  
Out Of Plane ◽  
A Cell ◽  
Plane Compression ◽  
Contractile Forces ◽  
Tissue Relaxation ◽  
Muscle Myosin

Apical constriction driven by non-muscle myosin II (″myosin″) provides a well-conserved mechanism to mediate epithelial folding. It remains unclear how contractile forces near the apical surface of a cell sheet drive out-of-plane bending of the sheet and whether myosin contractility is required throughout folding. By optogenetic-mediated acute inhibition of myosin, we find that during Drosophila mesoderm invagination, myosin contractility is critical to prevent tissue relaxation during the early, ″priming″ stage of folding but is dispensable for the actual folding step after the tissue passes through a stereotyped transitional configuration, suggesting that the mesoderm is mechanically bistable during gastrulation. Combining computer modeling and experimental measurements, we show that the observed mechanical bistability arises from an in-plane compression from the surrounding ectoderm, which promotes mesoderm invagination by facilitating a buckling transition. Our results indicate that Drosophila mesoderm invagination requires a joint action of local apical constriction and global in-plane compression to trigger epithelial buckling.

Experimental study of the out-of-plane dynamic behaviour of adhesively bonded composite joints using split Hopkinson pressure bars

2018 ◽  
Vol 52 (21) ◽  
pp. 2875-2885 ◽  
Author(s):  
S Sassi ◽  
M Tarfaoui ◽  
H Benyahia
Keyword(s):  
Strain Rate ◽  
Dynamic Behaviour ◽  
Dynamic Compression ◽  
Strain Rates ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Out Of Plane ◽  
Bonded Composite ◽  
Strong Material

The effect of the strain rate on the mechanical behavior and the damage of adhesively bonded joints is one of the most important factors to consider in designing them. Vast research has been carried out on the dynamic behaviour of adhesives at different strain rates; however, the investigation about the dynamic behaviour of the adhesively bonded joints is limited. In this paper, the main objective is to study and assess the effect of the strain rate on the out-of-plane mechanical behaviour of adhesively bonded joints under dynamic compression using Hopkinson bars. These joints are studied using glass/vinylester composite materials which are commonly used in naval applications. The experimantal results have shown a strong material sensitivity to strain rates. Moreover, damage investigations have revealed that the failure mainly occurred in the adhesive/adherent interface because of the brittle nature of the polymeric adhesive. Results have shown good agreement with the dependency of the dynamic parameters on strain rates.

scholarly journals Detection of debonding in adhesive joints using Lamb wave propagation

2019 ◽  
Vol 262 ◽  
pp. 10012
Author(s):  
Magdalena Rucka ◽  
Erwin Wojtczak ◽  
Jacek Lachowicz
Keyword(s):  
Wave Propagation ◽  
Lamb Waves ◽  
Visual Assessment ◽  
Guided Wave ◽  
Steel Plates ◽  
Experimental Investigations ◽  
Mechanical Degradation ◽  
Adhesively Bonded ◽  
Destructive Testing ◽  
Out Of Plane

Adhesively bonded joints are widely used in many branches of industry. Mechanical degradation of this type of connections does not have significant symptoms that can be noticed during visual assessment, so non-destructive testing becomes a very important issue. The paper deals with experimental investigations of adhesively bonded steel plates with different defects. Five samples (an intact one and four with damages in the form of partial debonding) were prepared. The inspection was conducted with the use of guided wave propagation method. Lamb waves were excited at one point of the sample, whereas the out-of-plane velocity signals were recorded in a number of points spread over the area of overlap. The processing of signals consisted of calculations of weighted root mean square (WRMS). The results of the analysis showed that the WRMS maps allow for identification and determination of size and shape of debonding areas.

Adhesively bonded glass-metal façade elements with composite structural behaviour under in-plane and out-of-plane loading

2019 ◽  
Vol 200 ◽  
pp. 109692
Author(s):  
Vlad Alexandru Silvestru ◽  
Georg Kolany ◽  
Bernhard Freytag ◽  
Jens Schneider ◽  
Oliver Englhardt
Keyword(s):  
Structural Behaviour ◽  
Adhesively Bonded ◽  
Out Of Plane ◽  
Glass Metal
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