Artificial Nacre with High Toughness Amplification Factor: Residual Stress‐Engineering Sparks Enhanced Extrinsic Toughening Mechanisms

2021 ◽  
pp. 2108267
Author(s):  
Yu‐Feng Meng ◽  
Yin‐Bo Zhu ◽  
Li‐Chuan Zhou ◽  
Xiang‐Sen Meng ◽  
Yu‐Lu Yang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Amplification Factor ◽  
Toughening Mechanisms ◽  
High Toughness ◽  
Stress Engineering

Residual Stress Engineering in Fatigue Resistant Welds

2013 ◽  
Vol 768-769 ◽  
pp. 613-619
Author(s):  
Majid Farajian ◽  
Zuheir Barsoum ◽  
Arne Kromm
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Body Of Knowledge ◽  
Fatigue Design ◽  
Welding Technology ◽  
Stress Engineering ◽  
Solid Foundation ◽  
Stress States ◽  
The Many ◽  
Quantitative Consideration

The developments in the field of residual stress determination during the last decades have contributed to a better understanding of the origins and sources of residual stresses in different engineering disciplines. The many investigations concerning the behavior of residual stresses under mechanical loading have also provided a solid foundation to clarify the important aspects of residual stresses and fatigue. The question that arises now is if this available body of knowledge is being used effectively in the field of welding technology to design and construct structures with better fatigue performances. In this paper the necessity of the development of the concept residual stress engineering for welds in which wanted residual stress states are tailored for specific cases by appropriate means will be discussed. The possibilities of the quantitative consideration of the benefits in the fatigue design codes will be presented in a practical example.

DEVELOPMENT OF CARBON-BASED COATING OF EXTREMELY HIGH TOUGHNESS WITH GOOD HARDNESS

2004 ◽  
Vol 03 (04n05) ◽  
pp. 571-578 ◽  
Author(s):  
S. ZHANG ◽  
X. L. BUI ◽  
Y. FU ◽  
H. DU
Keyword(s):  
Residual Stress ◽  
Contact Angle ◽  
Amorphous Carbon ◽  
High Hardness ◽  
Hydrophobic Surface ◽  
Nanocomposite Coating ◽  
High Toughness ◽  
Surface Contact ◽  
Surface Contact Angle ◽  
Carbon Based

Metallic Al was doped into amorphous carbon (a-C) to form a matrix of a-C(Al) of very low residual stress and high toughness at the expense of some hardness. Nanocrystallites of TiC (nc-TiC) of a few nanometers in size were embedded in this matrix to bring back the hardness. The nanocomposite coating of nc-TiC/a-C(Al) was deposited via co-sputtering of graphite, Ti , and Al targets. Although the nanocomposite coating exhibited a moderately high hardness (about 20 GPa), it possessed extremely high toughness (about 55% of plasticity during indentation deformation) and low residual stress (less than 0.4 GPa), smooth (Ra=5.5 nm ), and hydrophobic surface (contact angle with water reaches 100°).

Fracture Toughness and Magnetic Properties of Sm2Co17-Based Magnets

2013 ◽  
Vol 645 ◽  
pp. 81-84 ◽  
Author(s):  
Ai Kun Li ◽  
Li Ya Li ◽  
Yuan Dong Peng ◽  
Jian Hong Yi
Keyword(s):  
Fracture Toughness ◽  
Magnetic Properties ◽  
High Performance ◽  
Maximum Energy ◽  
Crack Deflection ◽  
Toughening Mechanisms ◽  
Screw Dislocations ◽  
Yield Plateau ◽  
High Toughness ◽  
Type Magnet

We present our findings of increased fracture toughness in high performance Sm2Co17-type magnet. The new Sm(Co 0.65 Fe 0.24 Cu 0.08 Zr 0.03)7.6magnet exhibits remanence of 11.13 kGs, maximum energy of 30.2 MGOe. This magnet shows not only a superhigh fracture toughness of 5.56 MPa m 1/2 but also distinguished yielding combined with an enhanced plastic plateau of 30 % to failure. It has been found that debonding, crack deflection, crac k branching and bridging are the major toughening mechanisms for the observed high toughness and long yield plateau. Long and straight screw dislocations observed in Sm rich precipitates accelerate the debonding of Sm rich grains.

X-Ray Stress Measurement of Alloy Steels X-Ray Study of Elastic Deformation for Alloy Steels with Composite Microstructures

1993 ◽  
Vol 37 ◽  
pp. 317-325
Author(s):  
Masaaki Tsuda ◽  
Tokimasa Goto ◽  
Toshihiko Sasaki ◽  
Yukio Hirose
Keyword(s):  
Residual Stress ◽  
Thermal Expansion ◽  
Elastic Deformation ◽  
Stress Measurement ◽  
Coefficient Of Thermal Expansion ◽  
Ray Method ◽  
Toughening Mechanisms ◽  
X Ray ◽  
Alloy Steels

Residual stress is inevitably introduced into composites because of the mismatch of the coefficient of thermal expansion, and it is different for each phase. The x-ray method can detect separately the stress in each phase, so will yield useful information for analyzing the toughening mechanisms of composites.

Laser Shock Peening to Repair, Design and Manufacture Current and Future Aircraft Structures by Residual Stress Engineering

2014 ◽  
Vol 891-892 ◽  
pp. 992-1000 ◽  
Author(s):  
Domenico Furfari
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Aircraft Structures ◽  
Area Of Interest ◽  
Aircraft Manufacturing ◽  
Stress Engineering ◽  
Shock Peening

This paper will provide an overview on potential applications for the aerospace industry for repairing aircraft as well as to ensure salvage for identified hot spots in terms of fatigue and crack growth performance. Residual stress engineering is a field of engineering aiming to improve the economic and ecological impact of future aircraft structures by controlling the residual stresses induced by Laser Shock Peening (LSP). Managing the residual stresses for designing structures represents an innovative approach for next generation aircraft. Predicting crack turning induced via a LSP treatment and the optimization of the LSP treatment itself for reaching the crack growth design stress for the targeted weight benefit will be discussed. Advanced forming processes in aircraft manufacturing represent another potential area of interest and the benefits and challenges of applying laser peen forming in this context will be presented. The aeronautical industry requirements for future developments of the laser shock process will also be included for applications ranging from the repair environment to design and manufacturing of aircraft structures.

Residual stress engineering in friction stir welds by roller tensioning

2009 ◽  
Vol 14 (2) ◽  
pp. 185-192 ◽  
Author(s):  
J. Altenkirch ◽  
A. Steuwer ◽  
P. J. Withers ◽  
S. W. Williams ◽  
M. Poad ◽  
...  
Keyword(s):  
Residual Stress ◽  
Friction Stir ◽  
Stress Engineering

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

Residual stress measurements and modeling of built-up Box-T sections

2021 ◽  
Vol 160 ◽  
pp. 107336
Author(s):  
Ziqian Zhang ◽  
Gang Shi ◽  
Xuesen Chen ◽  
Lijun Wang ◽  
Le Zhou
Keyword(s):  
Residual Stress ◽  
Stress Measurements

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

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