scholarly journals Adhesive Joint Stiffness in the Aspect of FEM Modelling

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3911 ◽  
Author(s):  
Anasiewicz ◽  
Kuczmaszewski
Keyword(s):  
Aluminum Alloy ◽  
Numerical Model ◽  
Young’S Modulus ◽  
Adhesive Joint ◽  
Structural Changes ◽  
Young's Modulus ◽  
Joint Stiffness ◽  
Experimental Tests ◽  
Boundary Zone ◽  
Adhesive Properties

The paper presents the results of nanoindentation testing, carried out along the thickness of the adhesive joint joining sheets of aluminum alloy. The purpose of the tests was to determine changes in the Young’s modulus in the joint resulting from the active impact of the joined aluminum alloy sheets on the adhesive during curing of the adhesive bond. Structural changes that take place during curing of the joint, especially in the boundary zone, can have a significant impact on the adhesive properties and consequently, on the adhesive joint strength. The Young’s modulus of the adhesive (Ek) in the joint assumes variable values as the distance from the connections changes. This phenomenon is called the apparent Young’s modulus. The problem is to define the size of the boundary zone in which the value of Ek significantly differs from the value in the so-called core. Based on the obtained results of experimental tests, a numerical model was built taking into account the observed differences in the properties of the joint material. The stress distribution in the adhesive joint, single-lap connection with the three-zone adhesive joint, was analyzed in comparison to the classical numerical model in which adhesive in the adhesive joint is treated as isotropic in terms of rigidity.

scholarly journals Apparent Young’s Modulus of the Adhesive in Numerical Modeling of Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 328
Author(s):  
Kamil Anasiewicz ◽  
Józef Kuczmaszewski
Keyword(s):  
Numerical Model ◽  
Young’S Modulus ◽  
Adhesive Joint ◽  
Young's Modulus ◽  
Precise Determination ◽  
Adhesive Joints ◽  
Experimental Conditions ◽  
Element Simulation ◽  
Joint Material

This article is an evaluation of the phenomena occurring in adhesive joints during curing and their consequences. Considering changes in the values of Young’s modulus distributed along the joint thickness, and potential changes in adhesive strength in the cured state, the use of a numerical model may make it possible to improve finite element simulation effects and bring their results closer to experimental data. The results of a tensile test of a double overlap adhesive joint sample, performed using an extensometer, are presented. This test allowed for the precise determination of the shear modulus G of the cured adhesive under experimental conditions. Then, on the basis of the research carried out so far, a numerical model was built, taking the differences observed in the properties of the joint material into account. The stress distribution in a three-zone adhesive joint was analyzed in comparison to the standard numerical model in which the adhesive in the joint was treated as isotropic. It is proposed that a joint model with three-zones, differing in the Young’s modulus values, is more accurate for mapping the experimental results.

scholarly journals A study into the structure and physical properties of the Cr18Ni9-grade steel following long-term irradiation as part of the BN-600 reactor internals

2020 ◽  
Vol 6 (1) ◽  
pp. 1-6
Author(s):  
Irina A. Portnykh ◽  
Aleksandr V. Kozlov ◽  
Valery L. Panchenko ◽  
Vyacheslav S. Shikhalev
Keyword(s):  
Physical Properties ◽  
Young’S Modulus ◽  
Structural Changes ◽  
Young's Modulus ◽  
Void Size ◽  
Initial State ◽  
Porosity Distribution ◽  
Grade Steel ◽  
Reactor Internals

The microstructures and physical properties of the austenitic Cr18Ni9-grade steel after 22 and 33 years of operation as part of the reactor internals were tested for assessing the conditions of the BN-600 reactor non-replaceable components (internals) and the potential of their subsequent use in predicting the reactor ultimate life. The paper presents histograms of the porosity distribution depending on the void size, in samples taken from portions that were subjected to neutron irradiation with displacement rates ranging from 1.0×10–9 to 4.3×10–8 dpa/s at temperatures from 370 to 440 °C. The elasticity characteristics were measured by resonance-type ultrasonic technique for the samples taken from the same portions of material. It was demonstrated that swelling calculated using the histograms of the porosity distribution depending on the void size has the maximum value at ~415 °C and after 33 years of irradiation reaches values of ~3%. Long-term variations of Young’s modulus demonstrate non-monotonous dependence on the damage dose. The maximum relative variation of Young’s modulus after 22 and 33 years of operation does not exceed 2% and 6%, respectively, of the values corresponding to the initial state. It was shown that along with the irradiation-induced swelling the changes in the physical properties are also affected in the process of irradiation by other structural changes and, in particular, by the formation of secondary phases. As shown by the results of the studies, operation of the BN-600 reactor internals made of Cr18Ni9-grade steel can be extended beyond 33 years of service. The comparison of the results obtained for the material after 22 and 33 years of operation contains information required for describing subsequent changes of the structure and properties of the Cr18Ni9 internals. The obtained results can be used for forecasting the reactor ultimate life within the framework of existing and developed models.

Stiffening Effects of Tubes in Heat Exchanger Tubesheet

1984 ◽  
Vol 106 (3) ◽  
pp. 237-246 ◽  
Author(s):  
T. Terakawa ◽  
A. Imai ◽  
K. Yagi ◽  
Y. Fukada ◽  
K. Okada
Keyword(s):  
Heat Exchanger ◽  
Young’S Modulus ◽  
Tube Wall ◽  
Young's Modulus ◽  
Perforated Plate ◽  
Load Condition ◽  
Experimental Tests ◽  
Uniaxial Tensile ◽  
Hydraulic Test ◽  
Tube Heat Exchanger

Strain-measuring tests were performed with strain gages on rectangular coupons taken from perforated plate with triangular pitch under both uniaxial tensile loads and pure bending loads. The effective Young’s modulus obtained from the tests have strong correlation with the values recommended by the ASME Code. Next, to evaluate the stiffening effects of tubes, similar strain-gage tests were performed for different types of perforated coupons. One type had the tubes strength welded into the penetration holes of the test coupons. Another type had the tubes both expanded and strength welded into the test coupons. Stiffening effects of tubes are clearly obtained from these tests. Judging from the effective Young’s modulus of triangular pitch obtained by the testing, the recommended minimum credit given to the tube wall is 50 percent under elastic load condition. In addition, for experimental tests on an actual large-sized shell-and-tube heat exchanger under hydraulic test condition, good correlation was obtained between calculated and measured stress when full credit was taken for the tube wall in the calculation.

scholarly journals Theoretical and experimental investigation of MWCNT dispersion effect on the elastic modulus of flexible PDMS/MWCNT nanocomposites

2021 ◽  
Vol 11 (1) ◽  
pp. 55-64
Author(s):  
Pardis Ghahramani ◽  
Kamran Behdinan ◽  
Rasool Moradi-Dastjerdi ◽  
Hani E. Naguib
Keyword(s):  
Elastic Modulus ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Testing Machine ◽  
Experimental Tests ◽  
Weight Fraction ◽  
Experimental Results ◽  
Multiwalled Carbon ◽  
Displacement Mode ◽  
Theoretical Predictions

Abstract In this article, Young’s modulus of a flexible piezoresistive nanocomposite made of a certain amount of multiwalled carbon nanotube (MWCNT) contents dispersed in polydimethylsiloxane (PDMS) has been investigated using theoretical and experimental approaches. The PDMS/MWCNT nanocomposites with the governing factor of MWCNT weight fraction (e.g., 0.1, 0.25, and 0.5 wt%) were synthesized by the solution casting fabrication method. The nanocomposite samples were subjected to a standard compression test to measure their elastic modulus using Instron Universal testing machine under force control displacement mode. Due to the costs and limitations of experimental tests, theoretical predictions on the elasticity modulus of such flexible nanocomposites have also been performed using Eshelby–Mori–Tanaka (EMT) and Halpin–Tsai (HT) approaches. The theoretical results showed that HT’s approach at lower MWCNT contents and EMT’s approach at higher MWCNT contents have a better agreement to experimental results in predicting the elastic modulus of PDMS/MWCNT nanocomposites. The experimental results indicated that the inclusion of MWCNT in the PDMS matrix resulted in a noticeable improvement in Young’s modulus of PDMS/MWCNT nanocomposite at small values of MWCNT contents (up to w f = 0.25%); however, exceeding this nanofiller content did not elevate Young’s modulus due to the emergence of MWCNT agglomerations in the nanocomposite structure.

In Situ Measurement of the Young’s Modulus of an Embedded Inclusion by Acoustic Microscopy

1997 ◽  
Vol 119 (2) ◽  
pp. 143-147 ◽  
Author(s):  
S. Canumalla ◽  
G. A. Gordon ◽  
R. N. Pangborn
Keyword(s):  
Aluminum Alloy ◽  
Rayleigh Wave ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Target Material ◽  
Acoustic Microscopy ◽  
Alloy Matrix ◽  
Cross Sectional ◽  
Rayleigh Wave Speed

Alumina-silicate inclusions (shot) have been found to adversely affect the mechanical properties of a short alumina-silicate fiber reinforced aluminum alloy (A356). To better understand the differences between the responses of the shot and fibers to applied loads, the Young’s modulus of the shot is measured and compared to that of the fibers. The Rayleigh wave speed in the shot particle (cross-sectional area of 200 μm × 150 μm), measured in situ to be 4041 m/s using a scanning acoustic microscope, was used to calculate the Young’s modulus of the shot particle (132 GPa). The accuracy of the technique and the experimental arrangement used was verified to be better than four percent by independent measurements of the Rayleigh wave speeds in the aluminum alloy matrix and an embedded sapphire fiber. The fiber modulus was estimated to be 225 GPa based on a comparison of previously measured composite modulus with micromechanical predictions. Thus, shot was found to have a Young’s modulus 40 percent lower than that of the fibers. The applicability of the V(z) technique has been demonstrated for measuring the elastic properties over a microscopic area, even when the target material is an embedded inclusion.

scholarly journals Influence of Material on Wheelchair Vibrations

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 127
Author(s):  
Takeshi Waga ◽  
Soichiro Ura ◽  
Masahito Nagamori ◽  
Hisashi Uchiyama ◽  
Akira Shionoya
Keyword(s):  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
Young’S Modulus ◽  
Vibration Frequency ◽  
Weight Reduction ◽  
Young's Modulus ◽  
Specific Weight ◽  
Wheelchair Sports ◽  
The Difference

Wheelchair sports have a tendency to depend on the performance of wheelchairs, and the weight reduction of wheelchairs made of various alloys has helped improve the performance of players. Some players have mentioned, however, that the operability and riding comfort of competition wheelchair have been affected by changing the wheelchair materials; stiffness and weight are considered to be related to operability and riding comfort. In this experiment, we installed some weights on the center of the mass of a competitive wheelchair made of magnesium alloy to be the same mass of a wheelchair made of aluminum alloy; vibrations that occurred on both wheelchairs while driving were measured and compared. The experiment was performed using 3-axis sensors. This experiment showed that the vibration frequency of the wheelchair made of magnesium alloy was different from that made of aluminum alloy. This result was thought to be influenced by the difference in Young’s modulus or the specific weight.

Micromechanical Analysis of Excavation Damaged Zone in Anisotropic Rock Mass

2006 ◽  
Vol 324-325 ◽  
pp. 81-84
Author(s):  
Shu Hong Wang ◽  
Deng Pan Qiao ◽  
Peng Jia ◽  
Nan Zhang
Keyword(s):  
Rock Mass ◽  
Numerical Model ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Numerical Code ◽  
Loading Conditions ◽  
Underground Excavations ◽  
Anisotropic Rock ◽  
Rock Structure ◽  
Fracturing Process

Rock is a heterogeneous and anisotropic compound material, containing many shear surfaces, cracks, weak surfaces and faults. Damage and failure in a rock mass can occur through sliding along persistent discontinuities, or fractures. A new micromechanical approach to modeling the mechanical behavior of excavation damaged or disturbed zone (EDZ) of anisotropic rock is presented based on knowledge of the inhomogeneity of rock. In this numerical model, damage is analyzed as a direct consequence of microcracks growth. A study of the effect of elastic and failure anisotropy plus inhomogeneity on the underground excavations reveals that the modes of failure can be significantly influenced by the rock structure on the small and large scales. Fractures that develop progressively around underground excavations can be simulated using a numerical code called RFPA (Realistic Failure Process Analysis). This code incorporates the microscopic inhomogeneity in Young’s modulus and strength characteristic of rock. In the numerical models of a rock mass, values of Young’s modulus and rock strength are realized according to a Weibull distribution in which the distribution parameters represent the level of inhomogeneity of the medium. Another notable feature of this code is that no a priori assumptions need to be made about where and how fracture and failure will occur – cracking can occur spontaneously and can exhibit a variety of mechanisms when certain local stress conditions are met. These unique features have made RFPA capable of simulating the whole fracturing process of initiation, propagation and coalescence of fractures around excavations under a variety of loading conditions. The results of the simulations show that the code can be used not only to produce fracturing patterns similar to those reported in previous studies, but also to predict fracturing patterns under a variety of loading conditions. The numerical model was able to reproduce the associated complex stress patterns and the microseismic emission distribution for a variety of rock structural conditions.

scholarly journals Effect of Full Temperature Field Environment on Bonding Strength of Aluminum Alloy

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 657
Author(s):  
Haichao Liu ◽  
Yisa Fan ◽  
Han Peng
Keyword(s):  
Aluminum Alloy ◽  
Temperature Field ◽  
Young’S Modulus ◽  
Bonding Strength ◽  
Young's Modulus ◽  
Failure Criteria ◽  
Failure Strength ◽  
Bonded Joints ◽  
Different Temperatures ◽  
Full Temperature

In this paper, the influence of temperature on the bonding strength of aluminum alloy joints under the full temperature field is studied. Based on the service temperature range of vehicle bonding structures, the failure strength of aluminum alloy joints at different temperature points, namely −40 °C, −20 °C, 0 °C, 25 °C (RT), 40 °C, 60 °C and 80 °C, is tested. The results showed that compared with the failure strength of the adhesive at −40 °C, it decreased by 47.69% and 68.15% at RT and 80°C, respectively; the Young’s modulus of the adhesive decreased by 57.63% and 75.42% at RT and 80°C, respectively; with the increase of temperature, the young’s modulus, tensile strength and failure strain of the adhesive decreased. In addition, the failure strength of aluminum alloy joints varied with temperature. To be specific, the stiffness of joints decreased gradually from 25 °C to 80 °C and increased gradually from −40 °C. Based on the failure strength data of bonded joints at different temperature points, the secondary stress failure criteria of bonded joints at different temperatures were obtained. Then, the surface function of failure criteria under the full temperature field was established to provide reference for failure prediction of bonded structures under different temperatures and stresses.

scholarly journals Degradation of 3D-Printed Porous Polylactic Acid Scaffolds Under Mechanical Stimulus

2021 ◽  
Vol 9 ◽  
Author(s):  
Heming Chen ◽  
Quan Shi ◽  
Hengtao Shui ◽  
Peng Wang ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Numerical Model ◽  
Young’S Modulus ◽  
Polylactic Acid ◽  
Young's Modulus ◽  
Average Molecular Weight ◽  
Mechanical Stimulus ◽  
Number Average Molecular Weight ◽  
3D Printed

Polylactic acid (PLA) is a biodegradable polymer commonly used as a scaffold material to repair tissue defects, and its degradation is associated with mechanical stimulus. In this study, the effect of mechanical stimulus on the degradation of 3D-printed PLA scaffolds was investigated by in vitro experiments and an author-developed numerical model. Forty-five samples with porosity 64.8% were printed to carry out the degradation experiment within 90 days. Statistical analyses of the mass, volume fraction, Young’s modulus, and number average molecular weight were made, and the in vitro experiments were further used to verify the proposed numerical model of the scaffold degradation. The results indicated that the mechanical stimulus accelerated the degradation of the PLA scaffold, and the higher mechanical stimulus led to a faster degradation of the scaffolds at the late stage of the degradation process. In addition, the Young’s modulus and the normalized number average molecular weight of the PLA scaffolds between the experiments and the numerical simulations were comparable, especially for the number average molecular weight. The present study could be helpful in the design of the biodegradable PLA scaffolds.

Calorimetric and Thermomechanical Properties of Titanium-Based Orthodontic Wires: DSC–DMA Relationship to Predict the Elastic Modulus

2011 ◽  
Vol 26 (7) ◽  
pp. 829-844 ◽  
Author(s):  
Giuliana Laino ◽  
Roberto De Santis ◽  
Antonio Gloria ◽  
Teresa Russo ◽  
David Suárez Quintanilla ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Orthodontic Wires ◽  
Gum Metal

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young’s modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young’s modulus, and it can be particularly useful for the initial stage of orthodontic treatments.

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