An enhanced Johnson–Cook strength model for splitting strain rate and temperature effects on lower yield stress and plastic flow

2016 ◽  
Vol 113 ◽  
pp. 231-265 ◽  
Author(s):  
Luca Gambirasio ◽  
Egidio Rizzi
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Plastic Flow ◽  
Temperature Effects ◽  
Strength Model ◽  
Lower Yield ◽  
Lower Yield Stress

A Low Temperature Yield Instability in Iron

1960 ◽  
Vol 13 (2) ◽  
pp. 359 ◽  
Author(s):  
JB Lean
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Testing Machine ◽  
Strain Curve ◽  
Applied Strain ◽  
Lower Yield ◽  
Stress Strain Curve ◽  
Lower Yield Stress ◽  
Air Temperatures ◽  
The Difference

Polycrystalline specimens of a 0�07% C steel were tested in tension at liquid air temperatures. Under particular conditions of temperature and strain rate, following the upper yield point, the recorded stress descended below the lower yield stress then returned to the lower yield stress quasi. elastically thus forming a serration on the stress-strain curve. The magnitude of the serration depended on the difference between the upper and lower yield stresses, on the rigidity of the testing machine employed, and on the applied strain rate.

scholarly journals Evaluations of All-in-One, Polycarboxylate-Based Superplasticizer with Viscosity Modifying Agents for the Application of Normal-Strength, High-Fluidity Concrete

2021 ◽  
Vol 11 (23) ◽  
pp. 11141
Author(s):  
Tae-Woong Kong ◽  
Hyun-Min Yang ◽  
Han-Seung Lee ◽  
Chang-Bok Yoon
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Yield Stress ◽  
Lower Yield ◽  
Lower Yield Stress ◽  
Slump Flow ◽  
Different Types ◽  
Long Time ◽  
Normal Strength ◽  
Physical Phenomena

High fluidity concrete exhibits an excellent self-compacting property. However, the application of typical high-fluidity concrete is limited in the normal strength range (18~35 MPa) due to the large amount of binder. Therefore, it is important to solve these problems by adding a viscosity modifying agent (VMA) with a superplasticizer (PCE), which helps to improve the fluidity of the concrete. In addition, the rheology and stability of the concrete with VMA can be improved by preventing bleeding and segregation issues. Current studies focused on the physical phenomena of concrete such as the fluidity, rheological properties, and compressive strength of normal-strength, high-fluidity concrete (NSHFC) with different types of a polycarboxylate-based superplasticizer (NPCE). The obtained results suggested that the combinations of all-in-one polycarboxylate-based superplasticizers (NPCE) did not cause any cohesion or sedimentation even stored for a long time. The combination of three types of VMA showed the best fluidity (initial slump flow of 595~630 mm) without any segregation and bleeding, and the compressive strength at 28 days was also found to be the highest: 34–37 MPa. From these results, the combination of PCE (2.0%) + HPMC (0.3%) + WG (0.1%) + ST (0.1%) showed an 18% higher plastic viscosity and -4.4% lower yield stress than Plain.

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