Analysis of Shear Banding in Plane Strain Compression of a Bimetallic Thermally Softening Viscoplastic Body Containing an Elliptical Void

1991 ◽  
Vol 113 (4) ◽  
pp. 382-395 ◽  
Author(s):  
Z. G. Zhu ◽  
R. C. Batra
Keyword(s):  
Yield Stress ◽  
Plane Strain ◽  
Maximum Shear Stress ◽  
Matrix Material ◽  
The Body ◽  
Thin Layers ◽  
Soft Layer ◽  
Nominal Strain Rate ◽  
Layer Material ◽  
The Matrix

We study plane strain thermomechanical deformations of a prismatic viscoplastic body of square cross-section and deformed at a nominal strain-rate of 5000 s−1. The body has two thin layers placed symmetrically about the horizontal centroidal axis and an elliptical void at the center. The major axis of the void coincides with the vertical centroidal axis and also with the direction of loading. The layer material differs from that of the body in only the value of the yield stress in a quasistatic simple compression test. The yield stress for the layer material is taken to be either one-fifth or five times that of the matrix material. The deformations are assumed to be symmetrical about the vertical and horizontal centroidal axes. It is found that in each case shear bands initiate from points on the traction free edges where the matrix/layer interfaces intersect them and propagate into the softer material. For the soft layer these bands initially merge into one and propagate horizontally. Subsequently, each of these bands bifurcates into two which propagate into the matrix material along the direction of the maximum shear stress. There is minimal interaction between these bands and those initiating from points slightly away from the void tips. These latter bands pass through the soft layer rather easily. When the layer material is harder than the matrix material, the material in the first quadrant is eventually divided into five subregions each of which is deforming virtually rigidly and the velocity suffers a sharp jump across the boundaries between these regions.

scholarly journals The Effect of Thickness on the Properties of Laser-Deposited NiBSi-WC Coating on a Cu-Cr-Zr Substrate

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 127
Author(s):  
Yury Korobov ◽  
Yulia Khudorozhkova ◽  
Holger Hillig ◽  
Alexander Vopneruk ◽  
Aleksandr Kotelnikov ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Matrix Material ◽  
Copper Substrate ◽  
Thin Layers ◽  
Laser Deposition ◽  
The Matrix ◽  
High Level ◽  
Primary Carbides ◽  
Matrix Powder ◽  
Wear Tests

Ni/60WC coatings on copper substrate were placed via laser deposition (LD). A structural study was conducted using electron microscopy and a microhardness evaluation. Two body abrasive wear tests were conducted with a pin-on-plate reciprocating technique. A tool steel X12MF GOST 5960 (C-Cr-Mo-V 1.6-12-0.5-0.2) with a hardness of 63 HRC was used as a counterpart. The following results were obtained: Precipitation of the secondary carbides takes place in the thicker layers. Their hardness is lower than that of the primary carbides in the deposition (2425 HV vs. 2757 HV) because they mix with the matrix material. In the thin layers, precipitation is restricted due to a higher cooling rate. For both LD coatings, the carbide’s hardness increases compared to the initial mono-tungsten carbide (WC)-containing powder (2756 HV vs. 2200 HV). Such a high level of microhardness reflects the combined influence of a low level of thermal destruction of carbides during laser deposition and the formation of a boride-strengthening phase from the matrix powder. The thicker layer showed a higher wear resistance; weight loss was 20% lower. The changes in the thickness of the laser deposited Ni-WC coating altered its structure and wear resistance.

Fabrication and Characterization of TiNi/AL Smart Composites

2003 ◽  
Vol 785 ◽  
Author(s):  
Gyu Chang Lee ◽  
Jun Hee. Lee ◽  
Young Chul Park
Keyword(s):  
Composite Material ◽  
Shape Memory ◽  
Yield Stress ◽  
Room Temperature ◽  
Volume Fraction ◽  
Matrix Material ◽  
Al Alloy ◽  
Alloy Matrix ◽  
Strain Behavior ◽  
The Matrix

ABSTRACTAn attempt was made to fabricate composite material of an Al alloy matrix reinforced by TiNi shape memory fiber using a hot-press method and to investigate its microstructures and mechanical properties. The analysis of SEM and EDS showed that the composite material had good interface bonding. The stress-strain behavior of the composite material was evaluated at room temperature and 363 K as a function of pre-strain, and it showed that the yield stress at 363 K is higher than that at room temperature. It is also found that the yield stress of the composite material increased with increasing the amount of pre-strain and depended on the volume fraction of the fiber and heat treatment. The smartness of the composite could be given due to the shape memory effect of the TiNi fiber, which generated compressive residual stress in the matrix material when heated after being pre-strained. Microstructural observation revealed that interfacial reactions occurred between the matrix and fiber, creating two intermetallic layers.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Application of cross correlation to HREM images of surfaces

1987 ◽  
Vol 45 ◽  
pp. 754-755
Author(s):  
D. E. Luzzi ◽  
L. D. Marks ◽  
M. I. Buckett
Keyword(s):  
Cross Correlation ◽  
A Priori ◽  
Matrix Material ◽  
Correlation Method ◽  
Accurate Knowledge ◽  
Complex Image ◽  
Fourier Filtering ◽  
The Matrix ◽  
Low Pass ◽  
Data Reduction Technique

As the HREM becomes increasingly used for the study of dynamic localized phenomena, the development of techniques to recover the desired information from a real image is important. Often, the important features are not strongly scattering in comparison to the matrix material in addition to being masked by statistical and amorphous noise. The desired information will usually involve the accurate knowledge of the position and intensity of the contrast. In order to decipher the desired information from a complex image, cross-correlation (xcf) techniques can be utilized. Unlike other image processing methods which rely on data massaging (e.g. high/low pass filtering or Fourier filtering), the cross-correlation method is a rigorous data reduction technique with no a priori assumptions.We have examined basic cross-correlation procedures using images of discrete gaussian peaks and have developed an iterative procedure to greatly enhance the capabilities of these techniques when the contrast from the peaks overlap.

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

scholarly journals Self-Reinforced Nylon 6 Composite for Smart Vibration Damping

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1235
Author(s):  
Bidita Salahuddin ◽  
Rahim Mutlu ◽  
Tajwar A. Baigh ◽  
Mohammed N. Alghamdi ◽  
Shazed Aziz
Keyword(s):  
Matrix Material ◽  
Nylon 6 ◽  
Vibration Damping ◽  
Vibration Energy ◽  
Damping Factor ◽  
Passive Vibration Control ◽  
Reinforced Composite ◽  
Coiled Structure ◽  
The Matrix ◽  
3D Printed

Passive vibration control using polymer composites has been extensively investigated by the engineering community. In this paper, a new kind of vibration dampening polymer composite was developed where oriented nylon 6 fibres were used as the reinforcement, and 3D printed unoriented nylon 6 was used as the matrix material. The shape of the reinforcing fibres was modified to a coiled structure which transformed the fibres into a smart thermoresponsive actuator. This novel self-reinforced composite was of high mechanical robustness and its efficacy was demonstrated as an active dampening system for oscillatory vibration of a heated vibrating system. The blocking force generated within the reinforcing coiled actuator was responsible for dissipating vibration energy and increase the magnitude of the damping factor compared to samples made of non-reinforced nylon 6. Further study shows that the appropriate annealing of coiled actuators provides an enhanced dampening capability to the composite structure. The extent of crystallinity of the reinforcing actuators is found to directly influence the vibration dampening capacity.

scholarly journals The Dimension of the Body in Higher Education: Matrix of Meanings in Students’ Diaries

Human Arenas ◽  
2021 ◽  
Author(s):  
Ramiro Tau ◽  
Laure Kloetzer ◽  
Simon Henein
Keyword(s):  
Higher Education ◽  
Performing Arts ◽  
Teaching And Learning ◽  
Educational Practice ◽  
The Body ◽  
Cultural Perspective ◽  
General Process ◽  
Emotional Dimension ◽  
The Matrix ◽  
The Mind

AbstractIn this paper, we attempt to show some consequences of bringing the body back into higher education, through the use of performing arts in the curricular context of scientific programs. We start by arguing that dominant traditions in higher education reproduced the mind-body dualism that shaped the social matrix of meanings on knowledge transmission. We highlight the limits of the modern disembodied and decontextualized reason and suggest that, considering the students’ and teachers’ bodies as non-relevant aspects, or even obstacles, leads to the invisibilization of fundamental aspects involved in teaching and learning processes. We thus conducted a study, from a socio-cultural perspective, in which we analyse the emerging matrix of meanings given to the body and bodily engagement by students, through a systematic qualitative analysis of 47 personal diaries. We structured the results and the discussion around five interpretative axes: (1) the production of diaries enables historicization, while the richness of bodily experience expands the boundaries of diaries into non-textual modalities; (2) curricular context modulates the emergent meanings of the body; (3) physical and symbolic spaces guide the matrix of bodily meanings; (4) the bodily dimension of the courses facilitates the emergence of an emotional dimension to get in touch with others and to register one's own emotional experiences; and (5) the body functions as a condition for biographical continuity. These axes are discussed under the light of the general process of consciousness-raising and resignification of the situated body in the educational practice.

Investigation on the Influence of Pressure Terms in a Volume-Averaged Energy Balance in the Modelling of Liquid Composite Moulding Processes

2019 ◽  
Vol 809 ◽  
pp. 480-486
Author(s):  
Rohit George Sebastian ◽  
Christof Obertscheider ◽  
Ewald Fauster ◽  
Ralf Schledjewski
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Balance ◽  
Matrix Material ◽  
Energy Balance Equation ◽  
Manufacturing Processes ◽  
Composite Manufacturing ◽  
Liquid Composite Moulding ◽  
The Matrix ◽  
Computational Fluid Dynamics Cfd

The growing use of composite materials has generated interest in improving and optimising composite manufacturing processes such as Liquid Composite Moulding (LCM). In LCM, dry preforms are placed in a mould and impregnated with the matrix material. The efficiency of filling the moulds can be improved by using Computational Fluid Dynamics (CFD) filling simulations during the design of the mould. As part of an on-going effort to develop a CFD tool for the simulation of LCM processes, a volume averaged energy balance equation has been derived and implemented in a custom OpenFOAM solver. The energy balance is implemented in a custom OpenFOAM solver with and without the pressure terms for comparison with results from RTM experiments. It is found that the pressure terms do not significantly influence the results for LCM processes.

Localized Necking in a Round Tensile Bar with HCP Material Considering Tension-Compression Asymmetry in Plastic Flow

2013 ◽  
Vol 535-536 ◽  
pp. 164-167
Author(s):  
Jonghun Yoon ◽  
Oana Cazacu ◽  
Jung Hwan Lee
Keyword(s):  
Yield Criterion ◽  
Matrix Material ◽  
Ductile Failure ◽  
Material Behavior ◽  
Strength Differential ◽  
The Matrix ◽  
Void Evolution ◽  
Hcp Materials ◽  
Spherical Voids ◽  
Tension Compression Asymmetry

In spite of this progress in predicting ductile failure, the development of macroscopic yield criteria for describing damage evolution in HCP (hexagonal close-packed) materials remains a challenge. HCP materials display strength differential effects (i.e., different behavior in tension versus compression) in the plastic response due to twinning. Cazacu and Stewart [1] developed an analytic yield criterion for a porous material containing randomly distributed spherical voids in an isotropic, incompressible matrix that displays tension-compression asymmetry. The matrix material was taken to obey the isotropic form of the Cazacu et al. [2] yield criterion, which captures the tension-compression asymmetry of the matrix material. In this paper, finite element calculations of a round tensile bar are conducted with the material behavior described by the Cazacu and Stewart [1] yield criterion. The goal of these calculations is to investigate the effect of the tension-compression asymmetry on the necking induced by void evolution and propagation.

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