Interfacial Delamination of Inorganic Films on Viscoelastic Substrates

2016 ◽  
Vol 83 (10) ◽  
Author(s):  
Yin Huang ◽  
Jianghong Yuan ◽  
Yingchao Zhang ◽  
Xue Feng
Keyword(s):  
Structural Design ◽  
Composite Beam ◽  
Interfacial Crack ◽  
Stretchable Electronics ◽  
Beam Model ◽  
Interfacial Delamination ◽  
Inorganic Films ◽  
Potential Applications ◽  
Griffith’S Theory ◽  
Theory Of Viscoelasticity

The performance of flexible/stretchable electronics may be significantly reduced by the interfacial delamination due to the large mismatch at the interface between stiff films and soft substrates. Based on the theory of viscoelasticity, a cracked composite beam model is proposed in this paper to analyze the delamination of an elastic thin film from a viscoelastic substrate. The time-varying neutral plane of the composite beam is derived analytically, and then the energy release rate of the interfacial crack is obtained from the Griffith's theory. Further, three different states of the crack propagation under constant external loadings are predicted, which has potential applications on the structural design of inorganic flexible/stretchable electronics.

Topological Structural Design of Umbrella-Shaped Deployable Mechanisms Based on New Spatial Closed-Loop Linkage Units

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Wen-ao Cao ◽  
Donghao Yang ◽  
Huafeng Ding
Keyword(s):  
Structural Design ◽  
Closed Loop ◽  
Space Exploration ◽  
Degree Of Freedom ◽  
Structural Symmetry ◽  
Potential Applications ◽  
Good Potential

The umbrella linkage is one of the most classical deployable mechanisms. This paper concentrates on topological structural design of a family of umbrella-shaped deployable mechanisms based on new two-layer and two-loop spatial linkage units. First, deployable units are developed systematically from two-layer and two-loop linkage with four revolute pair (4R) coupling chains. Then, mobile connection modes of the deployable units are established based on the conditions of one degree-of-freedom (DOF) and structural symmetry. Finally, umbrella-shaped deployable mechanisms are constructed based on the developed deployable units and the established mobile connection modes. Like umbrellas, the designed deployable mechanisms can be actuated in a simple and reliable way, and those mechanisms have good potential applications in the fields of architecture, manufacturing, space exploration, and recreation.

Static and Dynamic Validations of a Refined Thin-Walled Composite Beam Model

AIAA Journal ◽  
2001 ◽  
Vol 39 (12) ◽  
pp. 2422-2424 ◽  
Author(s):  
Zhanming Qin ◽  
Liviu Librescu
Keyword(s):  
Composite Beam ◽  
Beam Model ◽  
Thin Walled

A nonlinear bilayer beam model for an interfacial crack in dielectric bimaterials under mechanical/electrical loading

2014 ◽  
Vol 188 (1) ◽  
pp. 47-58 ◽  
Author(s):  
MingHao Zhao ◽  
HaiTao Liu ◽  
CuiYing Fan ◽  
Ernian Pan ◽  
Tong-Yi Zhang
Keyword(s):  
Interfacial Crack ◽  
Beam Model ◽  
Electrical Loading

A composite beam model including variable warping effects derived from a generalized Saint Venant solution

2014 ◽  
Vol 110 ◽  
pp. 140-151 ◽  
Author(s):  
Andrea Genoese ◽  
Alessandra Genoese ◽  
Antonio Bilotta ◽  
Giovanni Garcea
Keyword(s):  
Composite Beam ◽  
Beam Model

Fatigue Delamination Crack Growth of Potting Compounds in PCB/Epoxy Interfaces Under Flexure Loading

2019 ◽  
Author(s):  
Pradeep Lall ◽  
Kalyan Dornala ◽  
Jeff Suhling ◽  
John Deep ◽  
Ryan Lowe
Keyword(s):  
Crack Growth ◽  
Shock Loading ◽  
Interfacial Crack ◽  
Mechanical Shock ◽  
Interfacial Delamination ◽  
Ultimate Elongation ◽  
Compound C ◽  
Stiff Material ◽  
Number Of Cycles ◽  
Potting Compound

Abstract Electronics components operating under extreme thermo-mechanical stresses are often protected with underfills and potting encapsulation to isolate the severe stresses. By encapsulating the entire PCB, the resin provides complete insulation for the unit thereby combining good electrical properties with excellent mechanical protection. In military and defense applications these components are often subjected to mechanical shock loads of 50,000g and are expected to perform with reliability. Due to the bulk of material surrounding the PCB, potting and encapsulation resins are commonly two-part systems which when mixed together form a solid, fully-cured material, with no by-products. The cured potting materials are prone to interfacial delamination under dynamic shock loading which in turn potentially cause failures in the package interconnects. The study of interfacial fracture resistance in PCB/epoxy potting systems under dynamic shock loading is important in mitigating the risk of system failure in mission critical applications. In this paper, three types of epoxy potting compounds were used as an encapsulation on PCB samples. The potting compounds were selected based on their ultimate elongation under quasi-static loading. Potting compound, A is a stiffer material with 5% of ultimate elongation before failure. Potting compound, B is a moderately stiff material with 12% ultimate elongation. Finally, potting compound C is a softer material with 90% ultimate elongation before failure. The fracture properties and interfacial crack delamination of the PCB/epoxy interface were determined using three-point bend loading with a pre-crack at the interface. The fatigue crack growth of the interfacial delamination was characterized for the three epoxy systems. A prediction of number of cycles to failure and the performance of different epoxy system resistance under cyclic bending loading was assessed.

Design and Development of a Novel 2-Degree-of-Freedom Parallel Robot

Robotica ◽  
2019 ◽  
Vol 38 (1) ◽  
pp. 1-14
Author(s):  
Changxi Cheng ◽  
Wenkai Huang ◽  
Chunliang Zhang
Keyword(s):  
Structural Design ◽  
Medical Science ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Static Stiffness ◽  
Reachable Workspace ◽  
Workspace Analysis ◽  
Potential Applications ◽  
Speed Performance

SummaryParallel robots are widely used in the fields of manufacturing, medical science, education, scientific research, etc. Many studies have been conducted on the topic already. However, shortcomings still exist, especially in certain situations. To meet the demand of good speed and load performances at the same time, this work presents a novel 2-degree-of-freedom parallel robot. The structural design, static, stiffness, and reachable workspace analysis of the robot are given in the manuscript. Experiment regarding the accuracy and speed performance is conducted, and the results are provided. In the end, potential applications of the proposed robot are suggested.

Cochlear partition stiffness—a composite beam model

1974 ◽  
Vol 55 (6) ◽  
pp. 1252-1258 ◽  
Author(s):  
P. Allaire ◽  
S. Raynor ◽  
M. Billone
Keyword(s):  
Composite Beam ◽  
Beam Model ◽  
Cochlear Partition

scholarly journals Mode II Fracture of GFRP Laminates Bonded Interfaces under 4-ENF Test

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Zhi-peng Zhong ◽  
Hong Liu
Keyword(s):  
Analytical Solutions ◽  
Shear Fracture ◽  
Interfacial Crack ◽  
Adhesive Layer ◽  
Mode Ii ◽  
Beam Model ◽  
Element Analysis ◽  
Mode Ii Fracture ◽  
Bonded Joint ◽  
Adhesively Bonded Joint

This experiment studies the mode II fracture behavior of an adhesively bonded joint composed of GFRP laminates. A new beam model is presented to calculate the mode II ERR for GFRP bonded 4-ENF specimens. In this model, the deformation of 4-ENF specimens caused by the relative deflection angle between the upper and lower layers and by the bending deformation of the upper and lower layers, respectively, is introduced; the effect of the adhesive layer deformation is presented. The closed-form analytical solutions of compliance and energy release rate based on the crack compliance method are obtained. The high accuracy of present analytical solutions are verified by finite element analysis through bonded GFRP 4-ENF specimens and compared to the rigid joint model and the CBT model. The interfacial crack propagation is numerically simulated using shear fracture toughness determined in this experiment, from which the predicted critical load results are in good agreement with the experimental results. The conclusion indicates that the compliance and ERR can accurately be predicted using the new bonded 4-ENF beam model.

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