Evaluation of Bond Strength With Void Subjected to Harmonic Peeling Loads

2001 ◽  
Author(s):  
A. Vaziri ◽  
H. R. Hamidzadeh ◽  
H. Nayeb-Hashemi
Keyword(s):  
Shear Stress ◽  
Dynamic Response ◽  
System Response ◽  
Harmonic Force ◽  
Adhesion Properties ◽  
High Adhesion ◽  
Initiation And Propagation ◽  
Bonded Joint ◽  
Out Of Plane ◽  
Bond Area

Abstract Joining components by using adhesives is becoming more popular with the development of adhesives with high adhesion properties. These components are often subjected to dynamic loading, which may cause initiation and propagation of failure in the joint. In order to ensure the reliability of these structures, their dynamic response and its variation with the presence of defects in the bonded area, must be understood. Dynamic response of a single lap joint subjected to an out of plane harmonic force is evaluated. The bonded joint is modeled as Euler Bernoulli beams, joined with an adhesive and constrained at one end and subjected to a harmonic force at the free end. The results show that the system response is not sensitive to a range of adhesive loss factor of 0-1. Furthermore, the system response is little affected by the presence of void in the bond area. The system response seems to be more sensitive to the void location than to its size. Peel and shear stress in bond area are obtained and found to be confined to the edge of the overlap. For adhesive and adherents properties and geometry investigated the maximum peel and shear stress in the bond area are little affected with the presence of a central void which covers less than 60% of the over lap length for all range of frequency. However, when the frequency of the applied load is close to the natural frequency of the structure, a void increases both maximum peel and shear stress.

Dynamic Response of Adhesively Bonded Beams Subjected to Harmonic Peeling Loads

1999 ◽  
Author(s):  
H. R. Hamidzadeh ◽  
J. L. Prescher ◽  
H. Nayeb-Hashemi
Keyword(s):  
Dynamic Response ◽  
Natural Frequency ◽  
System Response ◽  
Shear Stresses ◽  
Harmonic Force ◽  
Factors Affecting ◽  
Initiation And Propagation ◽  
Stress Changes ◽  
Bonded Joint ◽  
Out Of Plane

Abstract The only viable method to join some components is by using adhesive. These components are often subjected to dynamic loading, which may cause initiation and propagation of failure in the joint. In order to insure the reliability of these structures, their dynamic response and factors affecting their response must be understood. Dynamic response of a single lap joint subjected to an out of plane harmonic force is evaluated. The bonded joint is modeled as Euler Bernoulli beams joined with an adhesive and constrained at one end and subjected to a harmonic force at the free end. The results show that the system response is not sensitive to the damping characteristic of the adhesive. In contrast, the elastic properties, and geometry of adhesive and adherends dominate the response. Significant peel and shear stresses develop in the over lap. These stresses are confined to the edge of the overlap and their magnitude increases as the frequency approaches the natural frequency of the system. The results show that the direction of the shear stress changes as the frequency of applied load sweeps over the first natural frequency. In contrast the peeling stress direction does not change as result of sweeping frequency over the first natural frequency.

Correction: The Dynamic Response of a Pinhole Microphone under Flows of Varying Shear Stress

2018 ◽  
Author(s):  
N. Agastya Balantrapu ◽  
Russell J. Repasky ◽  
Liselle A. Joseph ◽  
William J. Devenport
Keyword(s):  
Shear Stress ◽  
Dynamic Response

scholarly journals Simulation of the Load Evolution of an Anchoring System under a Blasting Impulse Load Using FLAC3D

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xigui Zheng ◽  
Jinbo Hua ◽  
Nong Zhang ◽  
Xiaowei Feng ◽  
Lei Zhang
Keyword(s):  
Shear Stress ◽  
Dynamic Response ◽  
Axial Force ◽  
Mechanical Characteristics ◽  
Oscillation Amplitude ◽  
Anchoring System ◽  
Impulse Load ◽  
The Stability ◽  
Calculation Software ◽  
Dynamic Perturbation

A limitation in research on bolt anchoring is the unknown relationship between dynamic perturbation and mechanical characteristics. This paper divides dynamic impulse loads into engineering loads and blasting loads and then employs numerical calculation software FLAC3Dto analyze the stability of an anchoring system perturbed by an impulse load. The evolution of the dynamic response of the axial force/shear stress in the anchoring system is thus obtained. It is revealed that the corners and middle of the anchoring system are strongly affected by the dynamic load, and the dynamic response of shear stress is distinctly stronger than that of the axial force in the anchoring system. Additionally, the perturbation of the impulse load reduces stress in the anchored rock mass and induces repeated tension and loosening of the rods in the anchoring system, thus reducing the stability of the anchoring system. The oscillation amplitude of the axial force in the anchored segment is mitigated far more than that in the free segment, demonstrating that extended/full-length anchoring is extremely stable and surpasses simple anchors with free ends.

Are the dynamic response characteristics of brachial artery flow-mediated dilation sensitive to the magnitude of increase in shear stimulus?

2008 ◽  
Vol 105 (1) ◽  
pp. 282-292 ◽  
Author(s):  
K. E. Pyke ◽  
J. A. Hartnett ◽  
M. E. Tschakovsky
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Dynamic Response ◽  
Phase I ◽  
Brachial Artery ◽  
Flow Mediated Dilation ◽  
Final Phase ◽  
Stimulus Magnitude ◽  
Brachial Artery Diameter ◽  
Response Characteristics

The purpose of this study was to determine the dynamic characteristics of brachial artery dilation in response to step increases in shear stress [flow-mediated dilation (FMD)]. Brachial artery diameter (BAD) and mean blood velocity (MBV) (Doppler ultrasound) were obtained in 15 healthy subjects. Step increases in MBV at two shear stimulus magnitudes were investigated: large (L; maximal MBV attainable), and small (S; MBV at 50% of the large step). Increase in shear rate (estimate of shear stress: MBV/BAD) was 76.8 ± 15.6 s−1 for L and 41.4 ± 8.7 s−1 for S. The peak %FMD was 14.5 ± 3.8% for L and 5.7 ± 2.1% for S ( P < 0.001). Both the L (all subjects) and the S step trials (12 of 15 subjects) elicited a biphasic diameter response with a fast initial phase (phase I) followed by a slower final phase. Relative contribution of phase I to total FMD when two phases occurred was not sensitive to shear rate magnitude ( r2 = 0.003, slope P = 0.775). Parameters quantifying the dynamics of the FMD response [time delay (TD), time constant (τ)] were also not sensitive to shear rate magnitude for both phases (phase I: TD r2 = 0.03, slope P = 0.376, τ r2 = 0.04, slope P = 0.261; final phase: TD r2 = 0.07, slope P = 0.169, τ r2 = 0.07, slope P = 0.996). These data support the existence of two distinct mechanisms, or sets of mechanisms, in the human conduit artery FMD response that are proportionally sensitive to shear stimulus magnitude and whose dynamic response is not sensitive to shear stimulus magnitude.

Steel Sheet Shear Walls with Burring Holes for Low- to Mid-Rise Housings

2019 ◽  
Author(s):  
Yoshimichi Kawai ◽  
Shigeaki Tohnai ◽  
Shinichiro Hashimoto ◽  
Atsushi Sato ◽  
Tetsuro Ono
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Steel Sheet ◽  
Shear Walls ◽  
Shear Load ◽  
Finite Element Analyses ◽  
Plane Shear ◽  
Out Of Plane

<p>Steel sheet shear walls with cold formed edge stiffened burring holes are applied to low- to mid-rise housings in seismically active and typhoon- or hurricane-prone regions. A configuration with burrs on the inside and smooth on the outside enables the construction of omitting the machining of holes for equipments and thinner walls with simplified attachments of finishings. In-plane shear experiments and finite element analyses revealed that the walls allowed shear stress to concentrate in intervals between the burring holes. The walls maintained stable shear load and large deformation behavior, and the deformation areas were limited in the intervals and a large out-of-plane waveform in a sheet was effectively prevented owing to edge stiffened burring ribs. The design methods are developed for evaluating the shear load of the walls at story angle from zero to 1/100, using the idea of decreasing the band width of the inclined tension fields on the intervals with the effects of the thickness.</p>

scholarly journals Production of modified adhesive composites based on EVA and modified PE

2020 ◽  
pp. 45-47
Author(s):  
M. D. Sizova ◽  
A. N. Zelenetsky ◽  
V. Ya. Ivolgin
Keyword(s):  
Maleic Anhydride ◽  
Polymer Matrix ◽  
Morphological Changes ◽  
Adhesive Properties ◽  
Adhesion Properties ◽  
High Adhesion

An adhesive based on EVA and LDPE is developed which can be used up to 60°C. It was modified by polyisocyanate fragments of a grafted and reticulate nature for structural and morphological changes of the polymer matrix and improvement of physical, mechanical and adhesive properties. For additional compatibilization of the components, LDPE modified with maleic anhydride (MA) was used. High adhesion properties of the obtained composites were confirmed.

scholarly journals The Dynamic Response of Tuned Impact Absorbers for Rotating Flexible Structures

2005 ◽  
Vol 1 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Steven W. Shaw ◽  
Christophe Pierre
Keyword(s):  
Dynamic Response ◽  
Flexible Structures ◽  
Experimental Studies ◽  
Analytical Investigation ◽  
Design Parameters ◽  
System Response ◽  
Rotor Speed ◽  
Flexible System ◽  
Restoring Forces ◽  
And Performance

This paper describes an analytical investigation of the dynamic response and performance of impact vibration absorbers fitted to flexible structures that are attached to a rotating hub. This work was motivated by experimental studies at NASA, which demonstrated the effectiveness of these types of absorbers for reducing resonant transverse vibrations in periodically excited rotating plates. Here we show how an idealized model can be used to describe the essential dynamics of these systems, and used to predict absorber performance. The absorbers use centrifugally induced restoring forces so that their nonimpacting dynamics are tuned to a given order of rotation, whereas their large amplitude dynamics involve impacts with the primary flexible system. The linearized, nonimpacting dynamics are first explored in detail, and it is shown that the response of the system has some rather unique features as the hub rotor speed is varied. A class of symmetric impacting motions is also analyzed and used to predict the effectiveness of the absorber when operating in its impacting mode. It is observed that two different types of grazing bifurcations take place as the rotor speed is varied through resonance, and their influence on absorber performance is described. The analytical results for the symmetric impacting motions are also used to generate curves that show how important absorber design parameters—including mass, coefficient of restitution, and tuning—affect the system response. These results provide a method for quickly evaluating and comparing proposed absorber designs.

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