Extra strengthening and work hardening in gradient nanotwinned metals

Science ◽  
2018 ◽  
Vol 362 (6414) ◽  
pp. eaau1925 ◽  
Author(s):  
Zhao Cheng ◽  
Haofei Zhou ◽  
Qiuhong Lu ◽  
Huajian Gao ◽  
Lei Lu
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Mechanical Performance ◽  
Pure Copper ◽  
Atomistic Simulations ◽  
Gradient Structure ◽  
Mechanical Behaviors ◽  
Unusual Behavior ◽  
Properties Of Materials ◽  
Shed Light

Gradient structures exist ubiquitously in nature and are increasingly being introduced in engineering. However, understanding structural gradient–related mechanical behaviors in all gradient structures, including those in engineering materials, has been challenging. We explored the mechanical performance of a gradient nanotwinned structure with highly tunable structural gradients in pure copper. A large structural gradient allows for superior work hardening and strength that can exceed those of the strongest component of the gradient structure. We found through systematic experiments and atomistic simulations that this unusual behavior is afforded by a unique patterning of ultrahigh densities of dislocations in the grain interiors. These observations not only shed light on gradient structures, but may also indicate a promising route for improving the mechanical properties of materials through gradient design.

Evaluation and prediction of material fatigue characteristics under impact loads: review and prospects

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xintian Liu ◽  
Que Wu ◽  
Shengchao Su ◽  
Yansong Wang
Keyword(s):  
Mechanical Properties ◽  
Design Methodology ◽  
Mechanical Performance ◽  
Impact Load ◽  
Impact Loads ◽  
Content Type ◽  
Material Fatigue ◽  
Mechanical Properties Of Materials ◽  
Fatigue Characteristics ◽  
Properties Of Materials

PurposeThe properties of materials under impact load are introduced in terms of metal, nonmetallic materials and composite materials. And the application of impact load research in biological fields is also mentioned. The current hot research topics and achievements in this field are summarized. In addition, some problems in theoretical modeling and testing of the mechanical properties of materials are discussed.Design/methodology/approachThe situation of materials under impact load is of great significance to show the mechanical performance. The performance of various materials under impact load is different, and there are many research methods. It is affected by some kinds of factors, such as the temperature, the gap and the speed of load.FindingsThe research on mechanical properties of materials under impact load has the characteristics as fellow. It is difficult to build the theoretical model, verify by experiment and analyze the data accumulation.Originality/valueThis review provides a reference for further study of material properties.

Influence of gradient structure volume fraction on the mechanical properties of pure copper

2015 ◽  
Vol 645 ◽  
pp. 280-285 ◽  
Author(s):  
Xincheng Yang ◽  
Xiaolong Ma ◽  
Jordan Moering ◽  
Hao Zhou ◽  
Wei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Pure Copper ◽  
Gradient Structure

Mechanical Properties of Wear Tested LIGA Nickel

2004 ◽  
Vol 841 ◽  
Author(s):  
N. R. Moody ◽  
J. M. Jungk ◽  
M. S. Kennedy ◽  
S. V. Prasad ◽  
D. F. Bahr ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Friction And Wear ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Frictional Contacts ◽  
Indentation Tests ◽  
Work Hardening Coefficient ◽  
Silicon Based ◽  
Hardening Coefficient

ABSTRACTStrength, friction, and wear are dominant factors in the performance and reliability of materials and devices fabricated using nickel based LIGA and silicon based MEMS technologies. However, the effects of frictional contacts and wear on the mechanical performance of microdevices are not well-defined. To address these effects on performance of LIGA nickel, we have begun a program employing nanoscratch and nanoindentation. Nanoscratch techniques were used to generate wear patterns using loads of 100, 200, 500, and 990 μN with each load applied for 1, 2, 5, and 10 passes. Nanoindentation was then used to measure properties in each wear pattern correcting for surface roughness. The results showed a systematic increase in hardness with applied load and number of nanoscratch passes. The results also showed that the work hardening coefficient determined from indentation tests within wear patterns follows the work hardening behavior established from tensile tests, supporting use of a nanomechanics-based approach for studying mechanical properties of wear tested material.

Influence of Gradient Structure Volume Fraction on the Mechanical Properties of Pure Copper

2021 ◽  
pp. 473-488
Author(s):  
Xincheng Yang ◽  
Xiaolong Ma ◽  
Jordan Moering ◽  
Hao Zhou ◽  
Wei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Pure Copper ◽  
Gradient Structure

Mechanical Behaviors of Square Timber Columns Reinforced with AFRP under Axial Compression

2013 ◽  
Vol 790 ◽  
pp. 198-201 ◽  
Author(s):  
Shu Cheng Yuan ◽  
Jiang Feng Dong ◽  
Qing Yuan Wang
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Great Improvement ◽  
Carrying Capacity ◽  
Mechanical Performance ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Load Carrying Capacity ◽  
Mechanical Behaviors ◽  
Load Carrying

In order to apply original timber more effectively, the physical and mechanical properties of timber from camphor wood were tested. In total, seven square short timbers columns were fabricated, and then were reinforced by AFRP sheets with one, two and three layers in different reinforcing arrangements. The results showed that the columns with AFRP gave a great improvement in mechanical performance, and the loading carrying capacity, stiffness and ductility of the columns reinforced were also improved. The results also showed that the specimen with full wrapping of two layers of AFRP gave a higher deflection than the other ones. However, the load carrying capacity of the columns with AFRP arrangement decreased when the layers of AFRP sheets increased to three.

scholarly journals Mechanical properties of a hybrid auxetic metamaterial and metastructure system

2021 ◽  
pp. 073168442110095
Author(s):  
Wenjiao Zhang ◽  
Shuyuan Zhao ◽  
Rujie Sun ◽  
Fabrizio Scarpa ◽  
Jinwu Wang
Keyword(s):  
Mechanical Properties ◽  
Finite Elements ◽  
Internal Pressure ◽  
Flexible Electronics ◽  
Mechanical Performance ◽  
Unit Cell ◽  
Geometric Parameters ◽  
Mechanical Behaviors ◽  
Unit Cells ◽  
The One

We propose in this work an innovative hybrid auxetic metamaterial with a centersymmetric unit cell and tessellation topology similar to the one provided by the missing rib configuration. The tessellation proposed is applied to different core unit cells (star shape, cross-chiral shape with same dimensions, and reentrant). The effects of the geometric parameters of the cells on the in-plane mechanical properties of this hybrid auxetic metamaterial system are investigated via finite elements (FEMs). Representative unit cells (RUCs) with optimal mechanical behaviors are identified; those configurations exhibit the larger negative Poisson’s ratios and enhanced specific moduli. Designs related to two groups of auxetic metastructures with cylindric and cubic shapes are then developed based on the optimized RUCs along x and y directions. The equivalent mechanical performance of these metastructures under internal pressure is evaluated from a numerical standpoint. Auxetic cylindrical metastructures can be tailored by adjusting the number of the optimized RUCs along the circumferential and longitudinal directions, together with the geometric parameters of the optimized RUC itself. These hybrid auxetic metamaterials and metastructures provide the potential for multifunctional applications in biomechanics, flexible electronics, and aerospace.

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