Maximum Reduction in Thickness in a Single Sheet Forming Pass Based on Unified Strength Theory

2012 ◽  
Vol 159 ◽  
pp. 151-155 ◽  
Author(s):  
Xiao Wei Li ◽  
Jun Hai Zhao ◽  
Qi Yao Wang
Keyword(s):  
Compression Ratio ◽  
Yield Criterion ◽  
Sheet Forming ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Maximum Reduction ◽  
Special Cases ◽  
Wide Range ◽  
Tension And Compression ◽  
Single Sheet

Based on unified strength theory, the equation for estimating the maximum reduction in thickness in a single sheet forming pass is obtained. Included the contribution of both intermediate principal shear stress and varying tension-compression-ratio to material mechanical property, the equation developed by this paper can reasonably apply to a wide range of material. It can be proved that the equation for estimating the maximum reduction based on unified strength theory becomes that based on unified yield criterion, when material has equal strength in tension and compression, i.e., the tension-compression-ratio of material is equal to units; and, that the values of the maximum reduction obtained previously based on Mises, or Tresca criterion, are all just special cases of those based on unified yield criterion. In addition, the maximum reduction in thickness for sheet drawing and extrusion is equal to one another.

Unified Stresses Solution for Sheet Forming

2012 ◽  
Vol 463-464 ◽  
pp. 629-633
Author(s):  
Xiao Wei Li ◽  
Jun Hai Zhao ◽  
Qi Yao Wang
Keyword(s):  
Shear Stress ◽  
Compression Ratio ◽  
Yield Criterion ◽  
Mechanical Analysis ◽  
Sheet Forming ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Tension And Compression ◽  
Special Case

Based on unified strength theory, the unified stresses solution for sheet forming is presented according to mechanical analysis developed, and accurate enough for much material due to the contributions of both intermediate principal shear stress and varying tension-compression-ratio included. Notably, by denoting a notation of h, the expressions presented to estimate stresses of billet for sheet forming can be apply to both drawing and extrusion. In addition, when material has identical strength in tension and compression, i.e., the tension-compression-ratio of the material is equal to unit, the stresses solution based on unified strength theory become that based on unified yield criterion. Accordingly, it can be proved that the stresses solution based on Mises criterion is just a special case of that based on unified yield criterion.

Stresses Unified Solution for Wire Forming Based on Unified Strength Theory

2012 ◽  
Vol 472-475 ◽  
pp. 835-838
Author(s):  
Xiao Wei Li ◽  
Jun Hai Zhao ◽  
Wei Chen
Keyword(s):  
Compressive Strength ◽  
Shear Stress ◽  
Compression Ratio ◽  
Yield Criterion ◽  
Wire Drawing ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Tension And Compression ◽  
The Wire ◽  
Special Case

For known well the contributions of both tension-compression-ratio of material and intermediate principal shear stress to wire forming, the wire forming problem is developed based on unified strength theory. By denoting a notation of D, the unified stresses solution for wire forming is gained, which is suitable to both wire drawing and extrusion. In addition, when material has identical strength in tension and compression, the stresses solution based on unified strength theory become that based on unified yield criterion. Notably, it is proved that the stresses of wire forming are independent of the intermediate principal shear stress. Whether any yield criterion (e.g., Mises, Tresca or unified yield criterion) is adopted, for it is assumed that the tensile and compressive strength is equal to one another, the stresses solution is as same as that based on unified yield criterion, and is merely a special case of the unified stresses solution developed by this paper.

Plastic Analysis of Metal Sheet Forming with SD Effects

2013 ◽  
Vol 299 ◽  
pp. 216-220
Author(s):  
Zhen Yu Chen ◽  
Chun Du Wu ◽  
Zhong Xian Wang
Keyword(s):  
Shear Stress ◽  
Yield Criterion ◽  
High Strength ◽  
Sheet Forming ◽  
Metal Sheet ◽  
Film Stress ◽  
Strength Differential ◽  
Thin Film Stress ◽  
Plastic Analysis ◽  
Tension And Compression

Generally, many high-strength alloy materials used in aerospace, power and chemical industries have strength differential effect in tension and compression (SD effects). Usually, in mechanical calculations of sheet metal forming, Treasca yield criterion and Mises yield criterion are applied. Because the yield criterions don’t take SD effects into consideration, the calculation result may have errors for certain materials. However, generalized twin shear stress yield criterion, which takes into account the influence of the intermediate principal stress, is more suitable for most metal materials than Mohr-Coulomb strength theory. Therefore, this article has made plastic analysis on thin film stress issues of metal sheet forming with generalized twin shear stress yield criterion. We have obtained a unified plastic solution to the internal and external stretching issue of thin material with rounded holes and different tension and compression ratio. Providing a new result with wider applicability is very significant.

New strength formulae for rock surrounding a circular opening

2013 ◽  
Vol 50 (7) ◽  
pp. 735-743 ◽  
Author(s):  
Wen Fan ◽  
Mao-hong Yu ◽  
Long-sheng Deng ◽  
Xianglin Peng ◽  
Li-wei Chen
Keyword(s):  
Plastic Material ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Special Cases ◽  
Elastic Plastic Material ◽  
Strength Models ◽  
Strength Formula ◽  
Strain Model

In this paper, the unified strength theory proposed by Yu Mao-hong in 1991 is used to develop new strength formulae for rock surrounding a tunnel. The new formulae can be applied to an elastic–plastic material. The formulae have a series of expressions with the unified parameter, especially variations such as the well-known Kastner and Airy formulae, which are widely used in rock mechanics and engineering. These formulae are derived on the basis of the Mohr–Coulomb strength criterion. For the strength-weakening (plastic-softening) of geomaterials, the analytical solutions for the radius of the plastic residual zones, radius of the plastic-softening zones, and displacement around the opening are presented according to the elastoplastic-softening – residual plastic, tri-linear stress–strain model. In addition, the derivation for the stress state in the surrounding rock is given. The Kastner formula, Airy formula, and available solutions can be considered as special cases in the new strength formula. The influence of softening, shear dilatancy, and different strength models on the results is analyzed. The results presented in this paper are useful for analyzing surrounding rock with various stress conditions and reinforcement of caves.

Mechanical Properties of the Ecological Filling Blocks of the New Composite Wall Based on the Unified Strength Theory

2011 ◽  
Vol 250-253 ◽  
pp. 843-848
Author(s):  
Wei Huang ◽  
Hao Zhen Wu ◽  
Guo Xin Chen ◽  
Yin Zhang ◽  
Jun Yuan Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Stress ◽  
Lightweight Concrete ◽  
Yield Criterion ◽  
Testing Machine ◽  
Wall Structure ◽  
Strength Theory ◽  
Stress Strain ◽  
Unified Strength Theory ◽  
Composite Wall

In order to make the new composite wall structure the group developed to adapt different regional natural conditions, and along with the demand of gradually in-depth study the damage characteristics of the new composite wall, need to research the mechanical properties of the wall filling materials. In this paper, the ZG-CSS Electronic Universal Testing Machine was used on the uniaxial compressive test of the three blocks(the mud billet block, the cotton stalk block, the recycled EPS lightweight concrete block), to analyze the failure characteristics of the blocks and the other mechanical properties, such as Poisson’s ratio, elastic modulus, then the full compressive stress-strain curves are given, and at last fitting the mathematical expression of the uniaxial compressive stress - strain curves. And this paper also gives the yield criterion based on the unified strength theory of the three ecological filling blocks.

Anti-Penetration Performance of Ceramic Composite Armor Analysis Based on the Unified Strength Theory

2012 ◽  
Vol 557-559 ◽  
pp. 353-356
Author(s):  
Bao Feng Li ◽  
Jian Zheng ◽  
Xin Hua Ni ◽  
Yan Mei Qu ◽  
Xiao Wen Li ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Ceramic Composite ◽  
Strength Theory ◽  
Experiment Data ◽  
Unified Strength Theory ◽  
Composite Armor ◽  
Long Rod ◽  
Ceramic Composite Armor ◽  
Dynamics Problems ◽  
Ceramic Targets

The resistance pressure was the key to solve these problems that long rod projectiles penetrated ceramic targets at high velocity. Based on the twin shear united strength theory and the A-T model, the penetration depth were calculated. But the calculation result didn’t agree with experiment data. So the tension-compression ratio was redefined to apply to the dynamics problems according to the experiment data. And satisfied results were obtained.

Mechanical Properties of the Ecological Filling Blocks of the New Composite Wall Based on the Unified Strength Theory

2015 ◽  
Vol 727-728 ◽  
pp. 15-20
Author(s):  
Wei Huang ◽  
Ting Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Stress ◽  
Lightweight Concrete ◽  
Yield Criterion ◽  
Testing Machine ◽  
Wall Structure ◽  
Strength Theory ◽  
Stress Strain ◽  
Unified Strength Theory ◽  
Composite Wall

In order to make the new composite wall structure the group developed to adapt different regional natural conditions, and along with the demand of gradually in-depth study the damage characteristics of the new composite wall, need to research the mechanical properties of the wall filling materials. In this paper, the ZG-CSS Electronic Universal Testing Machine was used on the uniaxial compressive test of the three blocks(the mud billet block, the cotton stalk block, the recycled EPS lightweight concrete block), to analyze the failure characteristics of the blocks and the other mechanical properties, such as Poisson’s ratio, elastic modulus, then the full compressive stress-strain curves are given, and at last fitting the mathematical expression of the uniaxial compressive stress - strain curves. And this paper also gives the yield criterion based on the unified strength theory of the three ecological filling blocks.

Upper Bound Solution for Ultimate Bearing Capacity of Foundation Based on Unified Strength Theory

2012 ◽  
Vol 446-449 ◽  
pp. 1751-1754
Author(s):  
Yao Tang ◽  
Ping Tang
Keyword(s):  
Bearing Capacity ◽  
Upper Bound ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Positive Effects ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Potential Capacity ◽  
Special Cases ◽  
Foundation Base

Based on unified strength theory, an upper bound solution for bearing capacity of foundation is established considering the strength of soil above the basement by using Prandtl slip model. The proposed method could be degenerated to classical slip-line method in some certain situations. A series of results could be presented by means of changing the parameters of unified strength theory. The results obtained by this proposed method are greater than those by Terzaghi method, which is mainly because the positive effects of soil strength above foundation base. Since unified strength theory could be simplified to Mohr-Coulomb strength theory in a certain situation, the results are close to those obtained by Meyerhof method. This proposed solution can consider the effects of intermediate principal stress so that we can make full use of the potential capacity of soil, which is a rigorous upper-bound solution. Other solutions are special cases of this proposed solution.

Elastic–Brittle–Plastic Analysis of Double-Layered Combined Thick-Walled Cylinder Under Internal Pressure

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Qian Zhu ◽  
Junhai Zhao ◽  
Changguang Zhang ◽  
Yan Li ◽  
Su Wang
Keyword(s):  
Internal Pressure ◽  
Principal Stress ◽  
Yield Criterion ◽  
Engineering Application ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
Material Behavior ◽  
Strength Theory ◽  
Special Cases ◽  
Walled Cylinder

The elastic–brittle–plastic unified solutions of limit internal pressure are presented for double-layered combined thick-walled cylinder by the triple-shear unified strength criterion. The unified solutions obtained in this paper are especially versatile that can take into account of material brittle softening and intermediate principal stress quantitatively. The conventional existing elastic-perfectly plastic solutions, based on the Tresca yield criterion, Mises yield criterion, or twin-shear strength theory, can be categorized as special cases of the present unified solutions which can overcome their shortages. Parametric studies were carried out to evaluate the influences of various factors such as brittle softening parameter, strength theory parameter, cohesion, internal friction angle, and intermediate principal stress coefficient on the unified solutions. It is shown that proper choices of failure criterion, material behavior model, and brittle softening are significant in combined cylinder design. The new solutions can be naturally degraded to the existing formula and agree well with the results of the prevailing failure criteria. It is concluded that the unified solutions have an important practical value for the optimum design and engineering application of combined thick-walled cylinder.

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