Effect of Deep Penetration of Interleaf on Delamination Resistance in GFRP

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Dakai Bian ◽  
Tizian Bucher ◽  
D. J. Shim ◽  
Marshall Jones ◽  
Y. Lawrence Yao
Keyword(s):  
Deep Penetration ◽  
Laminate Composites ◽  
Delamination Resistance ◽  
Resolution Imaging ◽  
Mechanical Tensile ◽  
Bond Glass ◽  
Crack Paths ◽  
Hot Melt ◽  
Fiber Fabric ◽  
Composite Toughness

The problem of improving the delamination resistance and toughness of laminate fiber-reinforced composites especially for the drop-off structure is receiving considerable attention with the increasing need and application in industries. A hot melt-bonding process is developed to bond glass fabric laminates and the thermoplastic (TP) polysulfone (PSU) interleaf prior to the vacuum assisted resin transfer molding (VARTM) of laminate composites. The TP interleaf is heated above the glass transition temperature to reduce the viscosity when penetrating deeply into the glass fiber fabric. Mechanical tensile testing is performed to quantify the effects of the penetration depth on composite delamination resistance and composite toughness under different melt-bonding temperatures. Crack paths are observed by optical microscopy to characterize the crack propagation and arrest mechanism. Postmortem high-resolution imaging of the fracture surfaces is used to characterize the toughening mechanism of the TP interleaf reinforcements by using scanning electron microscopy (SEM). With deep penetration of the interleaf into the fiber bundles, cracks arrested within the penetration region improve the toughness by avoiding the cracks to reach the weak interface between interleaf and epoxy.

Interlaminar Toughening of GFRP—Part I: Bonding Improvement Through Diffusion and Precipitation

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Dakai Bian ◽  
Bradley R. Beeksma ◽  
D. J. Shim ◽  
Marshall Jones ◽  
Y. Lawrence Yao
Keyword(s):  
Crack Propagation ◽  
Reaction Rate ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Precipitation Process ◽  
Toughening Mechanism ◽  
Delamination Resistance ◽  
The Cost ◽  
Modified Epoxy ◽  
Crack Paths

A low concentrated polystyrene (PS) additive to epoxy is used, since it is able to reduce the curing reaction rate but not at the cost of increasing viscosity and decreasing glass transition temperature of the curing epoxy. The modified epoxy is cocured with a compatible thermoplastic interleaf during the vacuum assisted resin transfer molding (VARTM) to toughen the interlaminar of the composites. Using viscometry, the solubilities of thermoplastics (TPs) polycarbonate (PC), polyetherimide (PEI), and polysulfone (PSU) are determined to predict their compatibility with epoxy. The diffusion and precipitation process between the most compatible polymer PSU and epoxy formed semi-interpenetration networks (semi-IPN). To optimize bonding adhesion, these diffusion and precipitation regions were studied via optical microscopy under curing temperatures from 25 °C to 120 °C and PS additive concentrations to epoxy of 0–5%. Uniaxial tensile tests were performed to quantify the effects of diffusion and precipitation regions on composite delamination resistance and toughness. Crack paths were observed to characterize crack propagation and arrest mechanism. Fracture surfaces were examined by scanning electron microscopy (SEM) to characterize the toughening mechanism of the thermoplastic interleaf reinforcements. The chemically etched interface between diffusion and precipitation regions showed semi-IPN morphology at different curing temperatures. Results revealed deeper diffusion and precipitation regions increase energy required to break semi-IPN for crack propagation resulting in crack arrests and improved toughness.

Interlaminar Toughening of GFRP: Part 1 — Improved Diffusion and Precipitation

2017 ◽  
Author(s):  
Dakai Bian ◽  
Bradley R. Beeksma ◽  
D. J. Shim ◽  
Marshall Jones ◽  
Y. Lawrence Yao
Keyword(s):  
Crack Propagation ◽  
Reaction Rate ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Precipitation Process ◽  
Toughening Mechanism ◽  
Delamination Resistance ◽  
The Cost ◽  
Modified Epoxy ◽  
Crack Paths

A low concentrated polystyrene (PS) additive to epoxy is used since it is able to reduce the curing reaction rate but not at the cost of increasing viscosity and decreasing glass transition temperature of the curing epoxy. The modified epoxy is co-cured with a compatible thermoplastic interleaf during the vacuum assisted resin transfer molding (VARTM) to toughen the interlaminar of the composites. Using viscometry, the solubilities of thermoplastics polycarbonate (PC), polyetherimide (PEI), and polysulfone (PSU) are determined to predict their compatibility with epoxy. The diffusion and precipitation process between the most compatible polymer PSU and epoxy formed semiinterpenetration networks (semi-IPN). To optimize bonding adhesion, these diffusion and precipitation regions were studied via optical microscopy under curing temperatures from 25 C to 120 C and PS additive concentrations to epoxy of 0% to 5%. Uniaxial tensile tests were performed to quantify the effects of diffusion and precipitation regions on composite delamination resistance and toughness. Crack paths were observed to characterize crack propagation and arrest mechanism. Fracture surfaces were examined by scanning electron microscopy (SEM) to characterize the toughening mechanism of the thermoplastic interleaf reinforcements. The chemically etched interface between diffusion and precipitation region showed semi-IPN morphology at different curing temperatures. Results revealed deeper diffusion and precipitation regions increases energy required to break semi-IPN for crack propagation resulting in crack arrests and improved toughness.

Deep penetration of low velocity metal penetrators into ice

2021 ◽  
pp. 095440622110316
Author(s):  
Maxim Yurievich Orlov ◽  
Yulia Nikolaevna Orlova
Keyword(s):  
Numerical Modelling ◽  
Continuum Mechanics ◽  
High Strain ◽  
Computer Code ◽  
Deep Penetration ◽  
Strain Rates ◽  
Low Velocity ◽  
Crack Paths ◽  
Penetration Time ◽  
Model Crack

The paper summarizes the results of research of the destruction of an ice block with cylindrical and spherical penetrators at low velocity (≤325 m/s). The behaviour of ice at high strain rates is described by an elastic–plastic model of continuum mechanics. Numerical modelling of penetration is performed with IMPACT computer code. Algorithms of splitting nodes and destroying elements in a Lagrangian numerical method were modified to solve problems of penetration and perforation. The fracturing is described by a deterministic fracture model. Crack paths are examined; the damage is predicted and compared with existing experimental results. It was found that in the subsonic range of initial velocities the penetration time did not exceed 0.3 ms. Examination of the penetrators’ shapes showed that they were not plastic deformed.

An easily synthesized AIE luminogen for lipid droplet-specific super-resolution imaging and two-photon imaging

2021 ◽  
Author(s):  
Yanzi Xu ◽  
Haoke Zhang ◽  
Ning Zhang ◽  
Ruohan Xu ◽  
Zhi Wang ◽  
...  
Keyword(s):  
Penetration Depth ◽  
Lipid Droplet ◽  
Super Resolution ◽  
Deep Penetration ◽  
Two Photon ◽  
Resolution Imaging ◽  
Photon Imaging ◽  
Two Photon Imaging ◽  
Photo Stability ◽  
In Cells

A synergetic imaging platform was established to achieve LDs-specific imaging by STED nanoscopy and TPF microscopy. Benefiting from its high PLQYs, outstanding photo-stability, and high LDs specificity, a superior resolution in cells and a deep penetration depth in tissues were achieved.

scholarly journals Effect of Deep Penetration of Interleaf on Delamination Resistance in GFRP

2015 ◽  
Vol 1 ◽  
pp. 442-453 ◽  
Author(s):  
Dakai Bian ◽  
Tizian Bucher ◽  
Huade Tan ◽  
Y. Lawrence Yao
Keyword(s):  
Deep Penetration ◽  
Delamination Resistance

scholarly journals The Laser Interlaminar Reinforcement of Continuous Glass Fiber Composites

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Dakai Bian ◽  
Gen Satoh ◽  
Y. Lawrence Yao
Keyword(s):  
Crack Arrest ◽  
Glass Fabric ◽  
Reinforced Composites ◽  
Focal Volume ◽  
Laminate Composites ◽  
Glass Fiber Composites ◽  
Coupled Heat Transfer ◽  
Major Mode ◽  
Delamination Resistance ◽  
Interlaminar Crack

Interlaminar crack initiation and propagation are a major mode of failure in laminate fiber reinforced composites. A laser reinforcement process is developed to bond layers of glass fabric prior to the vacuum-assisted transfer molding of laminate composites. Glass fabric layers are bonded by fusing a dense glass bead to fibers within the laser focal volume, forming a 3D reinforcement architecture. Coupled heat transfer and viscous flow modeling is used to capture the temperature and morphology evolution of glass during the reinforcement process under experimentally observed conditions. Mode I double cantilever beam (DCB) testing is performed to quantify the effects of laser interlaminar reinforcements on composite delamination resistance. Postmortem high-resolution imaging of the fracture surface is used to characterize the toughening mechanism of the interlaminar reinforcements. Improved delamination resistance of laser reinforced composites derives from crack arrest and deflection mechanisms, showing a positive correlation to the reinforcement thickness.

Alternative approaches to ultra-high resolution imaging

1991 ◽  
Vol 49 ◽  
pp. 650-651
Author(s):  
J.M. Cowley
Keyword(s):  
High Resolution ◽  
High Voltage ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
High Resolution Imaging ◽  
General Applicability ◽  
Resolution Electron ◽  
Radiation Resistant ◽  
Resolution Imaging ◽  
Alternative Approaches

By extrapolation of past experience, it would seem that the future of ultra-high resolution electron microscopy rests with the advances of electron optical engineering that are improving the instrumental stability of high voltage microscopes to achieve the theoretical resolutions of 1Å or better at 1MeV or higher energies. While these high voltage instruments will undoubtedly produce valuable results on chosen specimens, their general applicability has been questioned on the basis of the excessive radiation damage effects which may significantly modify the detailed structures of crystal defects within even the most radiation resistant materials in a period of a few seconds. Other considerations such as those of cost and convenience of use add to the inducement to consider seriously the possibilities for alternative approaches to the achievement of comparable resolutions.

4-dimensional, high-resolution imaging of living cells

1992 ◽  
Vol 50 (1) ◽  
pp. 416-417
Author(s):  
Shinya Inoué
Keyword(s):  
Light Microscope ◽  
Living Cells ◽  
Live Cells ◽  
Video Tape ◽  
Active Living ◽  
High Resolution Imaging ◽  
3 Dimensional ◽  
Dynamic Architecture ◽  
Resolution Imaging ◽  
Disk Memory

This paper reports progress of our effort to rapidly capture, and display in time-lapsed mode, the 3-dimensional dynamic architecture of active living cells and developing embryos at the highest resolution of the light microscope. Our approach entails: (A) real-time video tape recording of through-focal, ultrathin optical sections of live cells at the highest resolution of the light microscope; (B) repeat of A at time-lapsed intervals; (C) once each time-lapsed interval, an image at home focus is recorded onto Optical Disk Memory Recorder (OMDR); (D) periods of interest are selected using the OMDR and video tape records; (E) selected stacks of optical sections are converted into plane projections representing different view angles (±4 degrees for stereo view, additional angles when revolving stereos are desired); (F) analysis using A - D.

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