Determination of the Temperature Dependent Dynamic Response of Elastomeric Materials Using the Split Hopkinson Pressure Bar

2006 ◽  
Author(s):  
Glenn E. Vallee ◽  
Steven D. Army

An effective, low cost method of determining the temperature dependent dynamic response of elastomeric materials at high strain rates using the Split Hopkinson Pressure Bar (SHPB) is developed. The test system allows the determination of the dynamic modulus at temperatures up to 150°C with control of specimen temperature within ± 3°C without the use of specialized equipment or cumbersome heating and positioning fixtures often required for temperature dependent testing. The test specimen is heated using a low cost electric resistance tape, which heats the transmitter and incident bars adjacent to the specimen. A finite element analysis is performed to predict the temperature vs. time response of the test specimen, which is verified using a simple thermocouple arrangement. The dynamic stress-strain response of a nitrile elastomer, commonly used as an impact absorber, is investigated over temperatures ranging from 20°C to 110°C at strain rates between 3000/s and 3500/s. The effect of strain rate on the dynamic modulus is not significant, but the effect of temperature is dramatic. The dynamic modulus of the nitrile is reduced by more than 60% at 110°C.

2018 ◽  
Vol 183 ◽  
pp. 01053
Author(s):  
Xueyang Li ◽  
Christian C. Roth ◽  
Dirk Mohr

Plasticity and fracture experiments are carried out on flat smooth and notched tensile specimens extracted from DP800 steel sheets. A split Hopkinson pressure bar testing system equipped with a load inversion device is utilized to reach high strain rates. Temperature dependent experiments ranging from 20°C to 300°C are performed at quasi-static strain rates. The material exposes a monotonic strain hardening behaviour with a non-monotonic temperature dependency. The rate-independent material behaviour at room-temperature is described with a non-associated Hill’48 plasticity model and an Swift-Voce strain hardening. A machine learning based model is used multiplicatively to capture the rate and temperature responses. A good agreement between measured and simulated force-displacement curves as well as local surface is obtained. The loading paths to fracture are then extracted to facilitate further development of a temperature dependent fracture initiation model.


2018 ◽  
Vol 183 ◽  
pp. 04005 ◽  
Author(s):  
Bar Nurel ◽  
Moshe Nahmany ◽  
Adin Stern ◽  
Nahum Frage ◽  
Oren Sadot

Additive manufacturing by Selective Laser Melting of metals is attracting substantial attention, due to its advantages, such as short-time production of customized structures. This technique is useful for building complex components using a metallic pre-alloyed powder. One of the most used materials in AMSLM is AlSi10Mg powder. Additively manufactured AlSi10Mg may be used as a structural material and it static mechanical properties were widely investigated. Properties in the strain rates of 5×102–1.6×103 s-1 and at higher strain rates of 5×103 –105 s-1 have been also reported. The aim of this study is investigation of dynamic properties in the 7×102–8×103 s-1 strain rate range, using the split Hopkinson pressure bar technique. It was found that the dynamic properties at strain-rates of 1×103–3×103 s-1 depend on a build direction and affected by heat treatment. At higher and lower strain-rates the effect of build direction is limited. The anisotropic nature of the material was determined by the ellipticity of samples after the SHPB test. No strain rate sensitivity was observed.


2013 ◽  
Vol 718-720 ◽  
pp. 112-116
Author(s):  
Xu Yang Li ◽  
Rui Yuan Huang ◽  
Yong Chi Li ◽  
Guang Fa Gao

The Split Hopkinson Pressure Bar (SHPB) is used to investigate the dynamic compressive mechanical behavior of a new foamed ceramic composite under impact loading. The stress versus strain curves are obtained under high strain rates. The test results are considered to be able to assure conformability of the tests, validate the stress equilibrium assumption, and show that the stress versus strain curves of foamed ceramic composite display strain hardening effect and damage softening effect as brittle materials. Meanwhile the curve includes short plateau region while no densification region.


2013 ◽  
Vol 631-632 ◽  
pp. 458-462 ◽  
Author(s):  
Peng Duo Zhao ◽  
Yu Wang ◽  
Jian Ye Du ◽  
Lei Zhang ◽  
Zhi Peng Du ◽  
...  

The strain rate sensitivity of neoprene is characterized using a modified split Hopkinson pressure bar (SHPB) system at intermediate (50 s-1, 100 s-1) and high (500 s-1, 1000 s-1) strain rates. We used two quartz piezoelectric force transducers that were sandwiched between the specimen and experimental bars respectively to directly measure the weak wave signals. A laser gap gage was employed to monitor the deformation of the sample directly. Three kinds of neoprene rubbers (Shore hardness: SHA60, SHA65, and SHA70) were tested using the modified split Hopkinson pressure bar. Experimental results show that the modified apparatus is effective and reliable for determining the compressive stress-strain responses of neoprene at intermediate and high strain rates.


2006 ◽  
Vol 306-308 ◽  
pp. 905-910 ◽  
Author(s):  
Zhi Hua Wang ◽  
Hong Wei Ma ◽  
Long Mao Zhao ◽  
Gui Tong Yang

The compressive deformation behavior of open-cell aluminum foams with different densities and morphologies was assessed under quasi-static and dynamic loading conditions. High strain rate experiments were conducted using a split Hopkinson pressure bar technique at strain rates ranging from 500 to 1 2000 − s . The experimental results shown that the compressive stress-strain curves of aluminum foams also have the “ three regions” character appeared in general foam materials, namely elastic region, collapse region and densification regions. It is found that density is the primary variable characterizing the modulus and yield strength of foams and the cell appears to have a negligible effect on the strength of foams. It also is found that yield strength and energy absorption is almost insensitive to strain rate and deformation is spatially uniform for the open-celled aluminum foams, over a wide range of strain rates.


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