Dynamic Strength Estimates for a High Strength, Experimental Steel

2005 ◽  
Author(s):  
Karen L. Torres ◽  
Hollie A. Clements ◽  
Stanley E. Jones ◽  
Morris Dilmore ◽  
Bradley Martin
Keyword(s):  
Strain Rate ◽  
Dynamic Testing ◽  
Dynamic Strength ◽  
High Strength ◽  
High Mass ◽  
Performance Requirements ◽  
Cylinder Test ◽  
Strain And Strain Rate ◽  
Initial Shock ◽  
The Impact

For several years, the Air Force has been engaged in the development of high velocity air to surface missiles. The objective is to replace larger, high mass weapons with smaller, more versatile projectiles that can achieve the same goals. The reduction of mass requires that the impact velocity be increased to meet the performance requirements. This has presented researchers with several challenges. First, the steel must be such that it survives the initial shock at impact. Second, because the tunnel is long, the material must resist friction and wear, which could erode the projectile nose, thereby degrading performance. The purpose of this paper is to present the results of dynamic testing of an experimental, high-strength steel. Using a one-dimensional model for the Taylor cylinder test, the constitutive behavior of the steel as a function of strain and strain-rate can be assessed through a strain-rate of roughly 105/second. This behavior is consistent with that required for successful modeling of the response of a penetrator casing in the ultra-ordinance velocity range.

Dynamic Strength Estimates for a High-Strength Experimental Steel

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
K. L. Torres ◽  
H. A. Clements ◽  
S. E. Jones ◽  
M. Dilmore ◽  
B. Martin
Keyword(s):  
Strain Rate ◽  
Dynamic Testing ◽  
Dynamic Strength ◽  
High Strength ◽  
High Mass ◽  
Performance Requirements ◽  
Cylinder Test ◽  
Strain And Strain Rate ◽  
Initial Shock ◽  
The Impact

For several years, the Air Force has been engaged in the development of high velocity air to surface missiles to defeat hard targets, such as concrete, sand, and soil. The objective is to replace larger, high mass weapons with smaller, more versatile projectiles that can achieve the same goals. The reduction of mass requires that the impact velocity be increased to meet the performance requirements. This has presented researchers with several challenges. First, the steel must be such that it survives the initial shock at impact. Second, because the travel distance in the target is long, the material must resist friction and wear, which could erode the projectile nose, thereby degrading performance. The purpose of this paper is to present the results of dynamic testing of an experimental high-strength steel, also called Eglin steel. Using a one-dimensional model for the Taylor cylinder test, the constitutive behavior of the steel as a function of strain and strain rate can be assessed through a strain rate of roughly 105∕s. This behavior is consistent with that required for successful modeling of the response of a penetrator casing in the ultra-ordinance velocity range.

Investigation on Microstructure and Martensitic Transformation Mechanism for the Warm-Stamped Third-Generation Automotive Medium-Mn Steel

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Xiaodong Li ◽  
Ying Chang ◽  
Cunyu Wang ◽  
Shuo Han ◽  
Daxin Ren ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Strain Rate ◽  
Compressive Load ◽  
High Strength ◽  
Third Generation ◽  
Transformation Mechanism ◽  
Loading Method ◽  
Strain And Strain Rate ◽  
Medium Mn Steel ◽  
Mn Steel

With the development of the automotive industry, the application of the high-strength steel (HSS) becomes an effective way to improve the lightweight and safety. In this paper, the third-generation automotive medium-Mn steel (TAMM steel) is studied. The warm-stamped TAMM steel holds the complete and fine-grained martensitic microstructure without decarbonization layer, which contributes to high and well-balanced mechanical properties. Furthermore, the martensitic transformation mechanism of the TAMM steel is investigated by the dilatation tests. The results indicate that the effects of the loading method on the Ms temperature under different loads are different. The Ms temperature is hardly influenced under the tensile loads and low compressive load. However, it is slightly decreased under the high compressive load. Moreover, the effects of the strain and strain rate on the Ms temperature are insignificant and can be neglected. As a result, this research proves that the martensitic transformation of the TAMM steel is rarely influenced by the process parameters, such as stamping temperature, loading method, load, strain, and strain rate. The actual stamping process can be designed and controlled accurately referring to the continuous cooling transformation (CCT) curves to realize the required properties and improve the formability of the automotive part.

scholarly journals Dynamic Characteristics of Deep Dolomite Under One-Dimensional Static and Dynamic Loads

2019 ◽  
Vol 101 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Jianguo Wang ◽  
Yang Liu ◽  
Kegang Li
Keyword(s):  
Strain Rate ◽  
Axial Compression ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Strength ◽  
Strong Positive Correlation ◽  
Hopkinson Pressure Bar ◽  
Irreversible Damage ◽  
One Dimensional ◽  
Rock Structure ◽  
The Impact

AbstractThe failure characteristics of rock subjected to impact disturbance under one-dimensional static axial compression are helpful for studying the problems of pillar instability and rock burst in deep, high geostress surrounding rock under blasting disturbances. Improved split Hopkinson pressure bar equipment was used for one-dimensional dynamic–static combined impact tests of deep-seated dolomite specimens under axial compression levels of 0, 12, 24, and 36 MPa. The experimental results demonstrate that the dolomite specimens exhibit strong brittleness. The dynamic strength always maintains a strong positive correlation with the strain rate when the axial compression is fixed; when the strain rate is close, the dynamic elasticity modulus and peak strength of the specimens first increase and then decrease with the increase in axial compression, and the peak value appears at 24 MPa. The impact resistance of specimens can be enhanced when the axial compression is 12 or 24 MPa, but when it increases to 36 MPa, the damage inside the specimen begins to cause damage to the dynamic rock strength. Prior to the rock macroscopic failure, the axial static load changes the rock structure state, and it can store strain energy or cause irreversible damage.

Researches on Effect of Impact Micro-Damages in Contact Layer on Machinability in Quick-Point Grinding

2008 ◽  
Vol 389-390 ◽  
pp. 229-234 ◽  
Author(s):  
Shi Chao Xiu ◽  
Suo Xian Yuan ◽  
Guang Qi Cai
Keyword(s):  
Surface Roughness ◽  
Strain Rate ◽  
Ground Surface ◽  
Dynamic Strength ◽  
Contact Layer ◽  
Grinding Process ◽  
Impact Process ◽  
Pile Up ◽  
Ground Surface Roughness ◽  
The Impact

Due to the high grinding speed and the less contact length, there is the super high material strain rate in the contact layer during quick-point grinding process. Based on the principle of micro-damages mechanics, it is the impact process between the workpiece and the grits on the wheel in the process. The weakening effects of the super high strain rate caused by the mechanical impact micro-damages and the adiabatic shearing damage can lower the dynamic strength of the material in contact layer and the micro-plastic pile-up deformation on the ground surface in the process. Therefore, it is possible to improve the surface integrity of the workpiece since the materials removal mechanism is changed in quick-point grinding process. In this paper, the impact performances and the model of quick point grinding process were studied. Based on the above, the model of the ground surface roughness related to the plastic pile-up deformation was established. The effects of the strain rate on the ground surface roughness and the materials removal ratio were analyzed. In addition, the grinding experiment was performed to testify such investigations. It is indicated that quick-point grinding is an impact process assuredly during the removing material process.

scholarly journals Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

2018 ◽  
Vol 8 (3) ◽  
pp. 371 ◽  
Author(s):  
Ben Lane ◽  
Paul Sherratt ◽  
Xiao Hu ◽  
Andy Harland
Keyword(s):  
Strain Rate ◽  
Tennis Ball ◽  
Strain And Strain Rate ◽  
The Impact

scholarly journals Dynamic Compressive Characteristics of Sandstone under Confining Pressure and Radial Gradient Stress with the SHPB Test

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Shiming Wang ◽  
Yunsi Liu ◽  
Jian Zhou ◽  
Qiuhong Wu ◽  
Shuyi Ma ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Peak Strain ◽  
Hopkinson Pressure Bar ◽  
Radial Gradient ◽  
The Impact

Research on the dynamic compressive characteristics of sandstone under radial gradient stress and confining pressure is conducive to understanding the characteristics of the surrounding rock, especially in an excavation operation for an underground mine roadway and tunnel. The present work aimed at studying the effects of radial gradient stress and confining pressure on the impact of compression of sandstone using a large-diameter split Hopkinson pressure bar. The results showed that the dynamic strength of sandstone under radial gradient stress increased with strain rate following a power function, and the dynamic strength of the sandstone under radial gradient stress was lower and more sensitive to strain rate. The increase in strain at peak stress (peak strain) was linearly correlated with the strain rate under different confining pressures. The sensitivity of the peak strain to confining pressure was lower for the sandstone with a hole, while the values of the elastic modulus were decreased. However, further increasing the stain rate would lead to an increase in the elastic modulus. Also, the ductility of the sandstone with a hole tested in this study was found to improve more significantly. Finally, with an increase in the incident energy, the absorbed energy per unit volume would increase, but would not be affected obviously by the radial gradient stress.

High-Rate Formability of High-Strength Aluminum Alloys: A Study on Objectivity of Measured Strain and Strain Rate

2015 ◽  
pp. 327-331
Author(s):  
Piyush Upadhyay ◽  
Aashish Rohatgi ◽  
Elizabeth V. Stephens ◽  
Richard W. Davies ◽  
David Catalini
Keyword(s):  
Aluminum Alloys ◽  
Strain Rate ◽  
High Strength ◽  
High Rate ◽  
Strain And Strain Rate ◽  
Measured Strain ◽  
High Strength Aluminum Alloys

High-Rate Formability of High-Strength Aluminum Alloys: A Study on Objectivity of Measured Strain and Strain Rate

2015 ◽  
pp. 327-331
Author(s):  
Piyush Upadhyay ◽  
Aashish Rohatgi ◽  
Elizabeth V. Stephens ◽  
Richard W. Davies ◽  
David Catalini
Keyword(s):  
Aluminum Alloys ◽  
Strain Rate ◽  
High Strength ◽  
High Rate ◽  
Strain And Strain Rate ◽  
Measured Strain ◽  
High Strength Aluminum Alloys

Research on the Mechanical Behavior of Styropor Concrete at High Strain Rates

2010 ◽  
Vol 168-170 ◽  
pp. 2086-2091
Author(s):  
Ze Bin Hu ◽  
Jin Yu Xu ◽  
Jie Zhu ◽  
Qiang He ◽  
Gang Li ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Strain ◽  
Dynamic Strength ◽  
Strain Rates ◽  
Average Strain ◽  
High Strain Rates ◽  
Average Strain Rate ◽  
The Impact

Mechanical behavior of Styropor concrete(EPSC) added with various volumetric fractions of EPS subjected to high strain rates were studied by using the Large-Diameter-SHPB. The infection of volumetric fractions and average strain rate to dynamic properties of EPSC were investigated. The experimental results show that under high strain rate condition, the dynamic strength, dynamic strength increase factor(DIF) and limit strain of EPSC are strain rate dependent, the strain rate effect can be expressed by linear approximations, and the relationship between elastic modulus and average strain rate is independent.With the addition of volumetric fractions of EPS, the impact compressive strength and elastic modulus of EPSC declines, and the toughness of EPSC is reinforced.

Study of Viscoplasticity Models for the Impact Behavior of High-Strength Steels

2006 ◽  
Vol 2 (2) ◽  
pp. 114-123 ◽  
Author(s):  
N. Peixinho ◽  
A. Pinho
Keyword(s):  
Strain Rate ◽  
Material Properties ◽  
High Strength Steels ◽  
High Strength ◽  
Impact Behavior ◽  
Dual Phase ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Trip Steels ◽  
The Impact

This study reports on modeling the mechanical behavior of high-strength steels subjected to impact loading. The materials studied were steel grades of interest for crashworthiness applications: dual-phase and transformation induced plasticity (TRIP) steels. The challenges associated with the numerical simulation of impact events involving these materials include the modeling of extensive plastic deformation, particularly the change of material properties with strain rate. Tensile testing was performed at different strain rates on the materials studied. The test results were used to compare and validate constitutive equations that provide a mathematical description of strain-rate dependence of the material properties. The Cowper–Symonds equation and modified variants were examined. The crashworthiness performance of thin-walled sections made of dual-phase and TRIP steels was also investigated. Axial crushing tests were performed at different speeds on top-hat and hexagonal tubes. The experimental results were compared with numerical simulations obtained using an explicit finite element program (LS-DYNA) and the original and modified Cowper–Symonds equations.

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