A Quantitative Test for Ozone Resistance of Rubber Vulcanizates

1974 ◽  
Vol 47 (4) ◽  
pp. 895-905 ◽  
Author(s):  
Z. W. Wilchinsky ◽  
E. N. Kresge
Keyword(s):  
Elastic Modulus ◽  
Energy Density ◽  
Critical Stress ◽  
Critical Strain ◽  
Tensile Force ◽  
Critical Value ◽  
Stored Energy ◽  
Simplified Procedure ◽  
Continuous Range ◽  
Ozone Resistance

Abstract A simplified procedure was developed for evaluating ozone resistance of rubber vulcanizates in terms of critical stress—strain and stored energy density parameters. A selected tensile force of appropriate magnitude is applied to a tapered specimen to produce a continuous range of stress. While thus stretched, the specimen is conditioned for 16 h, then exposed to ozone for 24 h. In the portion of the specimen where the stress is greater than a critical value σc, ozone cracking occurs, whereas in the portion of the specimen where the stress is less than σc there are no cracks. Values of σc the critical strain εc, the critical elastic stored energy Wc, and the elastic modulus E are determined from the position of the boundary between the cracked and uncracked zones, the average elongation of the stressed specimen, and the specimen geometry. The quantity Wc was found suitable for quantitatively characterizing ozone resistance by a single parameter.

Atomistic simulation of the uniaxial compression of black phosphorene nanotubes

2018 ◽  
Author(s):  
Van-Trang Nguyen ◽  
Minh-Quy Le
Keyword(s):  
Finite Element Method ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Uniaxial Compression ◽  
Critical Stress ◽  
Atomistic Simulation ◽  
Critical Strain ◽  
Bond Breaking ◽  
Black Phosphorene ◽  
Weber Potential

We study through molecular dynamics finite element method with Stillinger-Weber potential the uniaxial compression of (0, 24) armchair and (31, 0) zigzag black phosphorene nanotubes with approximately equal diameters. Young's modulus, critical stress and critical strain are estimated with various tube lengths. It is found that under uniaxial compression the (0, 24) armchair black phosphorene nanotube buckles, whereas the failure of the (31, 0) zigzag one is caused by local bond breaking near the boundary.

Storing Energy in the Mechanical Domain

2014 ◽  
Vol 1679 ◽  
Author(s):  
O.G. Súchil ◽  
G. Abadal ◽  
F. Torres
Keyword(s):  
Energy Source ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Critical Strain ◽  
Substrate Surface ◽  
Maximum Load ◽  
Linear Buckling ◽  
Initial Ph ◽  
Self Powered

ABSTRACTSelf-powered microsystems as an alternative to standard systems powered by electrochemical batteries are taking a growing interest. In this work, we propose a different method to store the energy harvested from the ambient which is performed in the mechanical domain. Our mechanical storage concept is based on a spring which is loaded by the force associated to the energy source to be harvested [1]. The approach is based on pressing an array of fine wires (fws) grown vertically on a substrate surface. For the fine wires based battery, we have chosen ZnO fine wires due the fact that they could be grown using a simple and cheap process named hydrothermal method [2]. We have reported previous experiments changing temperature and initial pH of the solution in order to determine the best growth [3]. From new experiments done varying the compounds concentration the best results of fine wires were obtained. To characterize these fine wires we have considered that the maximum load we can apply to the system is limited by the linear buckling of the fine wires. From the best results we obtained a critical strain of εc = 3.72 % and a strain energy density of U = 11.26 MJ/m3, for a pinned-fixed configuration [4].

Relationship between the stored energy density and intensity

1988 ◽  
Vol 84 (S1) ◽  
pp. S148-S148
Author(s):  
G. Maidanik ◽  
J. Dickey
Keyword(s):  
Energy Density ◽  
Stored Energy

scholarly journals Manufacturing Aluminum/Multiwalled Carbon Nanotube Composites via Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3927
Author(s):  
Eo Ryeong Lee ◽  
Se Eun Shin ◽  
Naoki Takata ◽  
Makoto Kobashi ◽  
Masaki Kato
Keyword(s):  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Energy Density ◽  
Laser Power ◽  
Multiwalled Carbon Nanotube ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Multiwalled Carbon ◽  
Powder Bed ◽  
Scan Speed

This study provides a novel approach to fabricating Al/C composites using laser powder bed fusion (LPBF) for a wide range of structural applications utilizing Al-matrix composites in additive manufacturing. We investigated the effects of LPBF on the fabrication of aluminum/multiwalled carbon nanotube (Al/MWCNT) composites under 25 different conditions, using varying laser power levels and scan speeds. The microstructures and mechanical properties of the specimens, such as elastic modulus and nanohardness, were analyzed, and trends were identified. We observed favorable sintering behavior under laser conditions with low energy density, which verified the suitability of Al/MWCNT composites for a fabrication process using LPBF. The size and number of pores increased in specimens produced under high energy density conditions, suggesting that they are more influenced by laser power than scan speed. Similarly, the elastic modulus of a specimen was also more affected by laser power than scan speed. In contrast, scan speed had a greater influence on the final nanohardness. Depending on the laser power used, we observed a difference in the crystallographic orientation of the specimens by a laser power during LPBF. When energy density is high, texture development of all samples tended to be more pronounced.

Effect of Thermo-Mechanical Variables on the Dynamic Ferrite Transformation Induced by Hot Deformation in 0.22C-Mn Steel

2006 ◽  
Vol 510-511 ◽  
pp. 510-513 ◽  
Author(s):  
Jae-Young An ◽  
Young Jae Kwon ◽  
S.I. Kim ◽  
Duk Lak Lee ◽  
Chong Mu Lee ◽  
...  
Keyword(s):  
Strain Rate ◽  
Critical Strain ◽  
High Strain ◽  
Stored Energy ◽  
Micro Structure ◽  
Dynamic Transformation ◽  
Austenite Grain ◽  
Nucleation Sites ◽  
Hot Torsion ◽  
Mn Steel

Hot torsion of a C (0.22 wt%)-Mn steel was used to investigate the influence of thermomechanical arameters on the strain induced dynamic transformation (SIDT) of ferrite. The pecimens were strained as a function of strain rate (0.05/sec - 5/sec) and strain (- 5.0) at right bove Ar3 temperature. The critical strain to initiate dynamically transformed ferrite nuclei during deformation increased as increasing the strain rate. On the other hand the completion of SIDT was hifted to larger strain by decreasing strain rate. This is due to the fact that the dynamic ransformation of ferrite was processed in the interior of austenite grain as well as at grain boundary y large stored energy and many nucleation sites for high strain rate. The dynamic transformed micro-structure of ferrite was developed to higher angle and the grain size could be refined to ~3 ㎛ at strain of 3.0 and 5/sec.

Simulation of a Layered Resonator for a Microfluidic Ultrasonic Separator

2006 ◽  
Author(s):  
Yijun Shen ◽  
Mark A. Atherton
Keyword(s):  
Energy Density ◽  
Pressure Distribution ◽  
Standing Wave ◽  
Acoustic Pressure ◽  
Separation Performance ◽  
Experimental Measurements ◽  
Driving Frequency ◽  
Stored Energy ◽  
Acoustic Characteristics ◽  
Small Spherical Particle

This paper focuses on the simulation of a layered resonator for a microfluidic ultrasonic separator with a special emphasis on analysing the stored energy-frequency product in the microfluid chamber. Since the acoustic force acting on a small spherical particle in a standing wave in the cavity of an ultrasonic separator is proportional to the product of the energy density in the standing wave and the driving frequency, the energy-frequency product can be used as a prediction of the separation performance in an ultrasonic separator. The electro-acoustic characteristics of the resonator under different conditions are also investigated. In particular, the influence of the reflector thickness on the stored energy-frequency product of the layered resonator is examined. Furthermore, the acoustic pressure distribution in the fluid chamber of the ultrasonic separator is investigated in detail. Predicted results from simulations compare well with experimental measurements and show that the model can be used to predict the electro-acoustic characteristics and the separation performance.

MATERIAL PROPERTIES OF ADULT RAT SKULL

2011 ◽  
Vol 11 (05) ◽  
pp. 1199-1212 ◽  
Author(s):  
HAOJIE MAO ◽  
CHRISTINA WAGNER ◽  
FENGJIAO GUAN ◽  
YENER N. YENI ◽  
KING H. YANG
Keyword(s):  
Elastic Modulus ◽  
Energy Density ◽  
Cross Sections ◽  
Material Properties ◽  
Soft Tissues ◽  
Beam Theory ◽  
Bending Stress ◽  
Adult Rats ◽  
Adult Rat ◽  
Young’S Moduli

Development of advanced computational rat head models requires accurate material properties of the rat brain, meninges, skull, and other soft tissues. This study investigated adult rat skull material properties, which are very limited in the current literature. A total of 20 skull specimens were harvested from 10 adult rats. High resolution (16 μm) microcomputed tomography scans were performed for each specimen to observe dimensional changes within each specimen and internal porosities through the cross sections. The specimens were tested in three-point bending at loading velocities of 0.02 and 200 mm/s. The elastic modulus, energy absorbed to failure, energy density, and bending stress were calculated using classical beam theory. Results demonstrated that bending velocity (strain rate) had significant effect on elastic modulus and bending stress, but not on energy and energy density. The Young's moduli of rat skull measured in this study were comparable to those measured from the adult human skull.

On the Onset of Dynamic Recrystallization in Steels

2011 ◽  
Vol 409 ◽  
pp. 431-436 ◽  
Author(s):  
Gonzalo Varela-Castro ◽  
Jose María Cabrera ◽  
J.M. Prado
Keyword(s):  
Dynamic Recrystallization ◽  
Critical Strain ◽  
Flow Behavior ◽  
Constitutive Models ◽  
Constant Strain Rate ◽  
Critical Value ◽  
Hot Forming ◽  
Wide Range ◽  
Precise Time ◽  
State Of Art

The knowledge of the flow behavior of metallic alloys subjected to hot forming operations is of particular interest for designers and engineers in the practice of industrial forming processes simulations (i.e. rolling mill). Nowadays dynamic recrystallization (DRX) is recognized as one of the most relevant and meaningful mechanisms available for the control of microstructure. This mechanism occurs during hot forming operations over a wide range of metals and alloys and it is known to be as a powerful tool which can be used to the control of the microstructure and properties of alloys. Therefore is important to know, particularly in low stacking fault energy (SFE) materials, the precise time for which DRX is available to act. At constant strain rate such time is defined by a critical strain, εc. Unfortunately this critical value is not directly measurable on the flow curve; as a result different methods have been developed to derive it. Focused on steels, in the present work the state of art on the critical strain for the initiation of DRX is summarized and a review of the different methods and expressions for determining εc is included. The collected data is suitable to feeding constitutive models.

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