Effect of Porosity on Dynamic Mechanical Properties and Impact Response Characteristics of High Aluminum Content PTFE/Al Energetic Materials

In order to obtain the effect of porosity on the dynamic mechanical properties and impact response characteristics of high aluminum content PTFE/Al energetic materials, PTFE/Al specimens with porosities of 1.2%, 10%, 20%, and 30% were prepared by adding additives. The dynamic compression properties and impact response characteristics of high aluminum content PTFE/Al energetic materials with porosity were studied by using a split Hopkinson pressure bar (SHPB) impact loading experimental system. Based on the one-dimensional viscoplastic hole collapse model, an impact temperature rise analysis model including melting effects was used, and corresponding calculation analysis was performed. The results show that with the increase of porosity, the yield strength and compressive strength of the material will decrease. Under dynamic loading, the reaction duration of PTFE/Al energetic materials with different porosities generally shows a tendency to become shorter as the porosity increases, while the ignition delay time is basically unchanged. In this experiment, the material response has the optimal porosity with the lowest critical strain rate, the optimal porosity for PTFE/Al energetic materials with different porosity and high aluminum content (50/50 mass ratio, size of specimens Φ8 × 5 mm) is 10%. The research results can provide an important reference for the engineering application of PTFE/Al energetic materials.

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Effect of Graphene Nanoplatelets Content on Dynamic Mechanical Property of GNPs/Ti Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.910.123 ◽

2018 ◽

Vol 910 ◽

pp. 123-129 ◽

Cited By ~ 1

Author(s):

X.N. Mu ◽

H.N. Cai ◽

Hong Mei Zhang ◽

Q.B. Fan ◽

Y. Wu

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Dynamic Stress ◽

Dynamic Compression ◽

Dynamic Mechanical Properties ◽

Graphene Nanoplatelets ◽

Matrix Composites ◽

Titanium Matrix ◽

Dynamic Mechanical ◽

Adiabatic Shearing

In this study, the titanium matrix composites (TiMCs) were fabricated by adding graphene nanoplatelets (GNPs). The dynamic compression test was carried out to study the effect of strain-rate and the GNPs content on dynamic mechanical properties of GNPs/Ti. Results show that the GNPs content (0wt%~0.8wt%) correspond to specific microstructure which affect the dynamic mechanical properties of the composites. Under high strain-rate (3500s-1), the 0.4wt%GNPs/Ti has the highest dynamic stress (~1860MPa) and strain (~30%). The adiabatic shearing band (ASB) microstructure of GNPs/Ti with various GNPs content has been observed under 3500s-1 strain-rate and the ASB microstructure evolution of 0.4wt%GNPs/Ti under different strain rate was investigated in particular.

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Comparative Analysis of Static and Dynamic Mechanical Behavior for Dry and Saturated Cement Mortar

Materials ◽

10.3390/ma12203299 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3299 ◽

Cited By ~ 2

Author(s):

Ayyaz Mustafa ◽

Mohamed A. Mahmoud ◽

Abdulazeez Abdulraheem ◽

Sarfaraz A. Furquan ◽

Ayman Al-Nakhli ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Comparative Analysis ◽

Mechanical Behavior ◽

Cement Mortar ◽

Water Saturation ◽

Dynamic Compression ◽

Impact Resistance ◽

Dynamic Mechanical Properties ◽

Dynamic Mechanical

Deformational and breakage behaviors of concrete and cement mortar greatly influence various engineering structures, such as dams, river bridges, ports, tunnels, and offshore rig platforms. The mechanical and petrophysical properties are very sensitive to water content and are controlled by the liquid part in pore spaces to a large extent. The objective of this paper is to investigate the water saturation effect on the strength characteristics and deformability of cement mortar under two loading conditions, static and dynamic compression. A set of cement mortar samples was prepared and tested to study the mechanical behavior in dry and saturated states. The first part of the research incorporates the study of static mechanical properties for dry and brine-saturated cement mortar through uniaxial compressive strength tests (UCS). Second, drop-weight impact experiments were carried out to study the dynamic mechanical properties (impact resistance, deformation pattern, and fracture geometry) for dry and saturated cases. The comparative analysis revealed that water saturation caused substantial changes in compressive strength and other mechanical characteristics. Under static loading, water saturation caused a reduction in strength of 36%, and cement mortar tended to behave in a more ductile manner as compared to dry samples. On the contrary, under dynamic loading conditions, water saturation resulted in higher impact resistance and fracture toughness as compared to dry conditions. In addition, fractures could propagate to smaller depths as compared to dry case. The study will help resolve many civil, mining, and petroleum engineering problems where cement structures undergo static as well as dynamic compression, especially in a hydraulic environment where these structures interact with the water frequently. To the best of our knowledge, the effect of water saturation on the dynamic mechanical properties of cement mortar has not been well understood and reported in the literature.

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Quasi-Static, Dynamic Compressive Properties and Deformation Mechanisms of Ti-6Al-4V Alloy with Gradient Structure

Metals ◽

10.3390/met11121928 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1928

Author(s):

Lei Lei ◽

Yongqing Zhao ◽

Qinyang Zhao ◽

Shewei Xin ◽

Cong Wu ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Dynamic Compression ◽

Dynamic Mechanical Properties ◽

Coarse Grained ◽

Lateral Side ◽

Gradient Structure ◽

Deformation Bands ◽

Compressive Properties ◽

Dynamic Mechanical

Gradient structure metals have good comprehensive properties of strength and toughness and are expected to improve the dynamic mechanical properties of materials. However, there are few studies on the dynamic mechanical properties of gradient structured materials, especially titanium alloys. Therefore, in this study, ultrasonic surface rolling is used to prepare a gradient structure layer on the surface of Ti-6Al-4V, and the quasi-static and dynamic compressive properties of coarse-grained Ti-6Al-4V (CG Ti64) and gradient-structured Ti-6Al-4V (GS Ti64) are investigated. The results show that a GS with a thickness of 293 µm is formed. The quasi-static compressive strength of GS Ti64 is higher than that of CG Ti64. Both CG Ti64 and GS Ti64 exhibit weak strain hardening effects and strain rate insensitivity during dynamic compression, and the compressive strength is not significantly improved. The lateral expansion of CG Ti64 is more obvious, while the lateral side of GS Ti64 is relatively straight, indicating that uniform deformation occurs in GS Ti64. The α phase in the GS produces dislocation cells and local deformation bands, and the lamellar structure is transformed into ultrafine crystals after dynamic compression. Both of them produce an adiabatic shear band under 2700 s−1, a large crack forms in CG Ti64, while GS Ti64 forms a small crack, indicating that GS Ti64 has better resistance to damage. The synergistic deformation of GS and CG promotes Ti-6Al-4V to obtain good dynamic mechanical properties.

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Strain rates effect of dynamic compression properties of E-glass / jute composite

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.3.2020.17.0562 ◽

2020 ◽

Vol 14 (3) ◽

pp. 7162-7169

Author(s):

Muhamad Shahirul Mat Jusoh ◽

Mohd Yazid Yahya ◽

Haris Ahmad Israr Ahmad

Keyword(s):

Mechanical Properties ◽

Hybrid Composite ◽

Split Hopkinson Pressure Bar ◽

Dynamic Testing ◽

Dynamic Compression ◽

Compressive Strain ◽

Dynamic Mechanical Properties ◽

Strain Rates ◽

Hopkinson Pressure Bar ◽

Dynamic Mechanical

Presently, the application of natural fibres widely gains attention from academia and industries as an alternative material in the composite system. The introduction of the hybrid composite using natural and synthetic fibres is extensively investigated on the static mechanical properties. However, the investigation on the high strain-rates effect is less reported due to the difficulty of the experimental set-up as well as the limitation of dynamic testing apparatus. The split Hopkinson pressure bar (SHPB) was utilised in this present study to characterise the dynamic mechanical properties of the hybrid composite between E-glass with jute fibres at three different strain rates of 755, 1363, and 2214 s−1. Results showed that the dynamic compression stress and strain of the tested samples significantly influenced by the value of strain rates applied. The E-glass/jute sample exhibited the strain-rate dependent behaviour, whereby the higher dynamic mechanical properties were recorded when the higher strain rates were imposed. The difference between maximum dynamic stress was 12.1 and 23.9% when the strain rates were increased from 755 to 1363 s−1 and 1363 to 2214 s−1, respectively. In terms of compressive strain, the maximum compressive strain was recorded when the lower strain rates were imposed during testing.

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TI-6AL-4V ALLOY FABRICATED BY LASER DIRECT DEPOSITION: DYNAMIC MECHANICAL PROPERTIES, CONSTITUTIVE MODEL, AND NUMERICAL SIMULATION

Surface Review and Letters ◽

10.1142/s0218625x19501919 ◽

2020 ◽

Vol 27 (08) ◽

pp. 1950191

Author(s):

TAO WANG ◽

WEILIN QIAO ◽

SHENG WANG ◽

ZHAN LI ◽

HAO WANG ◽

...

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Tensile Test ◽

Strain Rate ◽

Dynamic Compression ◽

Dynamic Mechanical Properties ◽

Strengthening Effect ◽

Dynamic Mechanical ◽

Direct Deposition ◽

Laser Direct Deposition

The dynamic mechanical properties of Ti-6Al-4V alloy prepared by laser direct deposition (LDD) at different strain rates are of great significance for the application of LDD technology in the manufacture and repair of aero-engine parts. The quasi-static tensile test and dynamic compression test of Ti-6Al-4V alloy prepared by LDD (LDD-Ti-6Al-4V) were carried out under the quasi-static and high strain rate using INSTRON-5982 tensile test equipment and Split Hopkinson pressure bar (SHPB) equipment. The true stress–strain curve is obtained, which indicates that the LDD-Ti-6Al-4V has a strain rate strengthening effect. Moreover, the Johnson–Cook (J–C) constitutive model of LDD-Ti-6Al-4V was fitted based on experimental data, and the experimental process of SHPB was numerically simulated. The simulation results are basically the same as the experimental results, which proves the correctness of the J–C constitutive model of LDD-Ti-6Al-4V.

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Dynamic Mechanical Properties and Constitutive Model of Selective Laser Melting 316L Stainless Steel at Different Scanning Speeds

10.21203/rs.3.rs-835137/v1 ◽

2021 ◽

Author(s):

Yongsheng Ge ◽

Jingfa Lei ◽

Tao Liu ◽

Wei Bai

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Constitutive Model ◽

Selective Laser Melting ◽

316L Stainless Steel ◽

Dynamic Compression ◽

Dynamic Mechanical Properties ◽

Laser Melting ◽

Dynamic Mechanical ◽

Experimental Apparatus

Abstract A 316L stainless steel material is widely used in the design of impact-resistant structures. Using selective laser melting (SLM) technology to form 316L stainless steel to study its mechanical behavior under dynamic loading is vital to improve the service performance of this product. This study investigates the dynamic compression mechanical properties and the constitutive models of 316L stainless steel specimens formed at different scanning speeds. The quasi-static and dynamic compression mechanical properties of SLM316L stainless steel specimens formed at four scanning speeds were tested using an electro-hydraulic servo experimental system and split Hopkinson pressure bar experimental apparatus. Microstructure observation was used to analyze the differences in the mechanical properties of specimens with different forming parameters. Finally, the modified Johnson-Cook (J-C) constitutive model was established and compared with the experimental data to illustrate the applicability of the modified model in describing the dynamic mechanical properties of SLM316l stainless steel. In dynamic compression mechanics experiments, the results show that SLM316L stainless steel specimens exhibit typical viscoplastic characteristics and significant strain rate strengthening effects. Furthermore, the scanning speed significantly affects the stacking characteristics of SLM-formed specimens, and the yield strength in axial compression decreases with the loss of stacking characteristics. Finally, the modified J-C model can accurately describe the mechanical properties of SLM316l stainless steel. This study can provide a theoretical model and methodological support for the design and development of SLM316l stainless steel.

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Coatings for TiAl

MRS Bulletin ◽

10.1557/s0883769400048193 ◽

1994 ◽

Vol 19 (10) ◽

pp. 31-34 ◽

Cited By ~ 9

Author(s):

Shigeji Taniguchi

Keyword(s):

Mechanical Properties ◽

Oxidation Resistance ◽

Aluminum Content ◽

Elevated Temperatures ◽

Surface Coatings ◽

Alloying Elements ◽

High Aluminum Content ◽

Automobile Engines ◽

Compound Tial ◽

High Aluminum

The intermetallic compound, TiAl, and materials based on it have been receiving considerable attention because of their high specific strengths at elevated temperatures. Their mechanical properties are being extensively studied, with a view to application in aircraft or automobile engines. Before using these materials at elevated temperatures, their interactions with the environment should be investigated and suitable measures taken to overcome any degradation. It has, however, been reported that protective Al2O3 scales do not form when TiAl is exposed to an oxidizing atmosphere in spite of its high aluminum content. The formation of an A12O3 scale, or at least a scale containing a continuous A12O3 layer, is a prerequisite for providing sufficient protection. Therefore, much effort has been expended in choosing suitable alloying additions. However, relatively less effort has been devoted to surface coatings on such materials. The purpose of the alloying addition is two-fold: to improve mechanical properties, particularly ductility, and to improve oxidation resistance. However, compatible alloying elements are rare. For instance, some elements which improve the ductility, e.g., vanadium, chromium, and manganese, lower the oxidation resistance. Accordingly, a reasonable concept for the designer is to add effective alloying elements to improve the mechanical properties and to apply a coating to provide protection against the environment. For improved reliability, elements that improve the oxidation resistance can also be added to increase the protection unless they reduce the required mechanical properties.

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