scholarly journals On Influence of Mechanical Properties of Gun Propellants on Their Ballistic Characteristics Determined in Closed Vessel Tests

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3243
Author(s):  
Radosław Trębiński ◽  
Jacek Janiszewski ◽  
Zbigniew Leciejewski ◽  
Zbigniew Surma ◽  
Kinga Kamińska
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Point Of View ◽  
Closed Vessel ◽  
Shape Functions ◽  
Stress Strain ◽  
Static Compression ◽  
Burning Process ◽  
Double Base ◽  
Gun Propellants

The geometric burning law of gun propellants is widely used in computer codes used for the simulations of the internal ballistics of guns. However, the results of closed vessel tests prove that the burning process of some propellants deviates from the geometric law. Validation of the hypothesis that observed deviations can be attributed to the cracking of propellant grains was the aim of this work. In order to verify the hypothesis, three types of gun propellants were chosen with considerably differing mechanical strengths: a single-base propellant, a double-base propellant, and a composite propellant. The mechanical properties of the gun propellants were tested using a quasi-static compression method with strain rate values of the order of 0.001 s−1 and the Split Hopkinson Pressure Bar technique with the strain rate in the range of 1000–6000 s−1. The mechanical responses of the propellants were assessed on the basis of the true stress–strain curves obtained and from the point of view of the occurrence of cracks in the propellant grains specimens. Moreover, closed vessel tests were performed to determine experimental shape functions for the considered gun propellants. Juxtaposition of the stress‒strain curves with the experimental shape functions proved that the observed deviations from the geometrical burning law can be attributed mainly to the cracking of propellant grains. The results obtained showed that the rheological properties of propellants are important not only from the point of view of logistical issues but also for the properly controlled burning process of propellants during the shot.

scholarly journals Investigation of the Mechanical Properties of St. Lawrence River Ice

1971 ◽  
Vol 8 (2) ◽  
pp. 163-169 ◽  
Author(s):  
L. W. Gold ◽  
A. S. Krausz
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Yield Stress ◽  
Power Law ◽  
River Ice ◽  
Stress Strain ◽  
Strain Behavior ◽  
Brittle Transition ◽  
Ductile To Brittle Transition ◽  
St Lawrence River

Observations are reported on the stress–strain behavior at −9.5 ± 0.5 °C of four types of ice obtained from the St. Lawrence River. The ice was subject to nominal rates of strain covering the range 2.1 × 10−5 min−1 to 5.8 × 10−2 min−1. A ductile-to-brittle transition was observed for strain rate of about 10−2 min−1. In the ductile range the four types had an upper yield stress that increased with strain rate according to a power law.

Mechanical Properties of ZDTP Tribofilms Measured by Nanoindentation: Strain Rate and Temperature Effects

2008 ◽  
Author(s):  
S. Bec ◽  
K. Demmou ◽  
J.-L. Loubet
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Film Formation ◽  
Point Of View ◽  
Effect Of Temperature ◽  
Zinc Dialkyldithiophosphate ◽  
Wear Rates ◽  
Versus Strain ◽  
Antiwear Action

This study aims to contribute to better understand the antiwear action of zinc dialkyldithiophosphate (ZDTP) additives used in car engine lubrication. The antiwear action of ZDTP is associated to the formation of a protective tribofilm onto the rubbing surface. On a mechanical point of view, the efficiency of ZDTP tribofilms results from equilibrium between film formation and wear rates, associated with appropriate rheological properties. In this work, the mechanical properties of a ZDTP tribofilm have been measured by nanoindentation in different test conditions in order to investigate the effect of temperature and strain rate. A Nanoindenter XP® entirely set into a climatic chamber was used to perform the nanoindentation tests. For all tests, an increase of the elastic modulus was observed from a threshold contact pressure value. This effect is similar to the anvil effect observed on polymers: in confined geometry, the elastic modulus increases versus hydrostatic pressure. For the tribofilm, in the studied range, this effect is enhanced at high temperature and low strain rate. Furthermore, when the temperature increases, a change in the rheological behavior of the tribofilm is observed. Up to about 50°C, the tribofilm exhibits viscoplastic behavior — the hardness increases versus strain rate — and above 50°C, the hardness decreases versus strain rate (“shear thinning-like” behavior).

scholarly journals Dynamic Constitutive Model of Ultra-High Molecular Weight Polyethylene (UHMWPE): Considering the Temperature and Strain Rate Effects

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1561 ◽  
Author(s):  
Kebin Zhang ◽  
Wenbin Li ◽  
Yu Zheng ◽  
Wenjin Yao ◽  
Changfang Zhao
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Plastic Material ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Ballistic Performance ◽  
Stress Strain ◽  
Different Temperatures

The temperature and strain rate significantly affect the ballistic performance of UHMWPE, but the deformation of UHMWPE under thermo-mechanical coupling has been rarely studied. To investigate the influences of the temperature and the strain rate on the mechanical properties of UHMWPE, a Split Hopkinson Pressure Bar (SHPB) apparatus was used to conduct uniaxial compression experiments on UHMWPE. The stress–strain curves of UHMWPE were obtained at temperatures of 20–100 °C and strain rates of 1300–4300 s−1. Based on the experimental results, the UHMWPE belongs to viscoelastic–plastic material, and a hardening effect occurs once UHMWPE enters the plastic zone. By comparing the stress–strain curves at different temperatures and strain rates, it was found that UHMWPE exhibits strain rate strengthening and temperature softening effects. By modifying the Sherwood–Frost model, a constitutive model was established to describe the dynamic mechanical properties of UHMWPE at different temperatures. The results calculated using the constitutive model were in good agreement with the experimental data. This study provides a reference for the design of UHMWPE as a ballistic-resistant material.

scholarly journals Analysis of Application of Plasma Ignition in Closed Vessel Tests

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6377
Author(s):  
Radosław Trębiński ◽  
Zbigniew Leciejewski ◽  
Zbigniew Surma ◽  
Jakub Michalski
Keyword(s):  
Plasma Jet ◽  
Comparative Investigation ◽  
Closed Vessel ◽  
Single Base ◽  
Burning Process ◽  
Plasma Ignition ◽  
Ballistic Properties ◽  
Double Base

This paper presents the results of a comparative investigation into the effects of the ignition method on the ballistic properties of three types of propellants: a single-base propellant, a double-base propellant and a low vulnerability (LOVA) propellant, as determined via closed vessel tests (CVT). Conventional gunpowder ignition and plasma jet ignition methods were used. The influence of the ignition method on the values of the propellant characteristics obtained in CVT was analysed. It was found that the method of ignition has an influence on the values of propellant characteristics, determined in CVT. An analysis of the experimental form functions showed that plasma ignition is not a solution to the problems inherent to the process of determining the ballistic properties of propellants in which the burning process deviates from the geometric burning law.

High Strain Rate Mechanical Properties of SAC-Q Between -65°C and +200°C After Exposure to Isothermal Aging

2020 ◽  
Author(s):  
Pradeep Lall ◽  
Vishal Mehta ◽  
Jeff Suhling ◽  
Ken Blecker
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Isothermal Aging ◽  
High Strain ◽  
Strain Rates ◽  
Solder Alloys ◽  
Stress Strain ◽  
Wide Range ◽  
Operating Temperatures ◽  
Electronic Parts

Abstract In many industries, such as automotive, oil and gas, aerospace, medical technologies, electronic parts can often be exposed to high strain loads during shocks, vibrations and drop-impact conditions. Such electronic parts can often be subjected to extreme low and high temperatures ranging from −65°C to 200°C. Also, these electronic devices can be subjected to strain rates of 1 to 100 per second in the critical environment. Recently, many doped SAC solder alloys are being introduced in the electronic component including SAC-Q, SAC-R, Innolot. SAC-Q is made with addition of Bi in Sn-Ag-Cu composition. Mechanical characteristic results and data for lead-free solder alloys are extremely important for optimizing electronic package reliability, at high temperature storage and elevated strain rates. Furthermore, the mechanical properties of solder alloys can be changed significantly due to a thermal aging, which is causing modification of microstructure. Data for the SAC-Q solder alloy with a high temp aging and testing at extreme low to high operating temperatures are not available. SAC-Q material was tested and analyzed for this study at range of operating temperatures of −65°C to 200°C and at a strain rate up to 75 per second. After the specimens were manufactured and reflowed, specimens were stored at 100°C for the isothermal aging for up to 90 days, before tensile tests were carried out at different operating temperatures. For the wide range of strain rates and test temperatures, stress-strain curves are established. In addition, the measured experimental results and data were fitted to the Anand viscoplasticity model and the Anand constants were calculated by estimating the stress-strain behavior measured in the wide range of operating temperatures and strain rates.

Measurement of Mechanical Properties of St 37 Material at High Strain Rates Using a Split Hopkinson Pressure Bar

2014 ◽  
Vol 660 ◽  
pp. 562-566 ◽  
Author(s):  
Akbar Afdhal ◽  
Leonardo Gunawan ◽  
Sigit P. Santosa ◽  
Ichsan Setya Putra ◽  
Hoon Huh
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Test Specimen ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

The dynamic mechanical properties of a material are important keys to investigate the impact characteristic of a structure such as a crash box. For some materials, the stress-strain relationships at high strain rate loadings are different than that at the static condition. These mechanical properties depend on the strain rate of the loadings, and hence an appropriate testing technique is required to measure them. To measure the mechanical properties of a material at high strain rates, ranging from 500 s-1 to 10000 s-1, a Split Hopkinson Pressure Bar is commonly used. In the measurements, strain pulses are generated in the bars system, and pulses being reflected and transmitted by a test specimen in the bar system are measured. The stress-strain curves as the material properties of the test specimen are obtained by processing the measured reflected and transmitted pulses. This paper presents the measurements of the mechanical properties of St 37 mild steel at several strain rates using a Split Hopkinson Pressure Bar. The stress-strain curves obtained in the measurement were curve fitted using the Power Law. The results show that the strength of St 37 material increases as the strain rate increases.

scholarly journals Influence of Size Effect on Dynamic Mechanical Properties of OFHC Copper at Micro/Mesoscopic Scale

2021 ◽  
Author(s):  
Chuanzhi Jing ◽  
Jilai Wang ◽  
Chengpeng Zhang ◽  
Yan Sun ◽  
Zhenyu Shi
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Strain Rate ◽  
Size Effects ◽  
Dynamic Mechanical Properties ◽  
Experimental Results ◽  
Ofhc Copper ◽  
Static Compression ◽  
Dynamic Mechanical ◽  
Macro Scale

Abstract The dynamic mechanical properties of metallic materials have been extensively investigated at the macro-scale in terms of deformation mechanisms, strain rate strengthening, and fracture mechanisms. However, the dynamic mechanical properties affected by size effects at micro/meso-scales have rarely been investigated. To explore the size effects on the dynamic mechanical properties at micro/meso-scales, the experiments of quasi-static compression and SHPB were carried out using oxygen-free, high-conductivity (OFHC) copper with different geometrical and grain sizes. The experimental results show that the quasi-static and dynamic mechanical properties of OFHC copper are affected by size effects at micro/meso-scales. In particular, OFHC copper exhibits strain rate strengthening effects at the micro/meso-scales, and the presence of micro-cracks was observed in the SHPB experimental specimens. The J-C constitutive model based on the surface layer model is proposed and the analysis of the average relative error of the modified model and the original constitutive model is performed. Finite element analysis was carried out based on the modified J-C model and the original model, and the results show that the modified J-C model was in good agreement with the experimental results.

Effect of Pre-Stress on the Dynamic Tensile Behavior of the TMJ Disc

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
J. Lomakin ◽  
P. A. Sprouse ◽  
M. S. Detamore ◽  
S. H. Gehrke
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Curve ◽  
Dynamic Mechanical Properties ◽  
Polymer Materials ◽  
Stress Strain ◽  
Dynamic Mechanical ◽  
Highly Nonlinear ◽  
Nonlinear Stress ◽  
Tmj Disc

Previous dynamic analyses of the temporomandibular joint (TMJ) disc have not included a true preload, i.e., a step stress or strain beyond the initial tare load. However, due to the highly nonlinear stress-strain response of the TMJ disc, we hypothesized that the dynamic mechanical properties would greatly depend on the preload, which could then, in part, account for the large variation in the tensile stiffnesses reported for the TMJ disc in the literature. This study is the first to report the dynamic mechanical properties as a function of prestress. As hypothesized, the storage modulus (E′) of the disc varied by a factor of 25 in the mediolateral direction and a factor of 200 in the anteroposterior direction, depending on the prestress. Multiple constant strain rate sweeps were extracted and superimposed via strain-rate frequency superposition (SRFS), which demonstrated that the strain rate amplitude and strain rate were both important factors in determining the TMJ disc material properties, which is an effect not typically seen with synthetic materials. The presented analysis demonstrated, for the first time, the applicability of viscoelastic models, previously applied to synthetic polymer materials, to a complex hierarchical biomaterial such as the TMJ disc, providing a uniquely comprehensive way to capture the viscoelastic response of biological materials. Finally, we emphasize that the use of a preload, preferably which falls within the linear region of the stress-strain curve, is critical to provide reproducible results for tensile analysis of musculoskeletal tissues. Therefore, we recommend that future dynamic mechanical analyses of the TMJ disc be performed at a controlled prestress corresponding to a strain range of 5–10%.

Tensile Mechanical Properties of AM50A Alloy by Hopkinson Bar

2007 ◽  
Vol 340-341 ◽  
pp. 247-254 ◽  
Author(s):  
Dong Wei Shu ◽  
Wei Zhou ◽  
Guo Wei Ma
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Tensile Stress ◽  
Strain Rate ◽  
Automotive Industry ◽  
Dynamic Stress ◽  
Hopkinson Bar ◽  
Strain Rates ◽  
Stress Strain ◽  
Stress Strain Relation

An ultralight magnesium alloy AM50A has been investigated for its potential to be used in aerospace and automotive industry. The dynamic stress strain relation of aluminum 6061 T6 and the magnesium alloy AM50A have been obtained by using the Hopkinson bar apparatus. The strain rates range between 600 s-1 and 1300 s-1. The Al 6061 T6 results tally well with those in literature. The magnesium alloy AM50A displays about 50% higher tensile stress at the strain rate of about 1300 s-1 than at static.

Influence of Strain Rate on Mechanical Properties of Shape Memory Alloy

2011 ◽  
Vol 467-469 ◽  
pp. 585-588 ◽  
Author(s):  
Zhen Qing Wang ◽  
Hong Shuai Lei ◽  
Bo Zhou ◽  
Yu Long Wang ◽  
Chen Zhang
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Strain Rate ◽  
Shape Memory ◽  
Critical Stress ◽  
Transformation Process ◽  
Test Results ◽  
Stress Strain ◽  
Loading Tests ◽  
New Equation

The influence of strain rate on mechanical properties of Ni-Ti SMA wires was investigated by a series of uniaxial loading tests. The influence of strain rate on critical stress was discussed. During the transformation process, the slop of the stress-strain curves was increasing with the increase of strain rate. A new equation was developed to describe the change of residual train based on the test results.

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