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Effects of pumice additions on thermal and mechanical behaviors of epoxy resin

Bulletin of the Polish Academy of Sciences Technical Sciences | 2023 | 71 | 4 | e146286 | DOI: 10.24425/bpasts.2023.146286

Keywords epoxy resin pumice thermal degradation thermal conductivity coefficient mechanical properties

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Abstract

In this study, thermal conductivity, mechanical properties, and thermal degradation of pumice-added epoxy materials were investigated. 2%, 4%, 6%, 8%, and 10% of pumice was added to the epoxy resin (EP) % by weight. Various types of analyses and tests were conducted to determine the thermal conductivity, mechanical properties, and thermal degradation of these epoxy materials. The tests and analyses proved that the addition of pumice leads to a decrease in the thermal conductivity coefficient and density of the pure EP material. It also increases the degree of hardness. The addition of pumice had a positive effect on mechanical properties. Compared to pure EP, it increased the tensile strength, Young’s modulus, bending strength, and flexural modulus. As a result of TGA analysis it was determined that with the incorporation of pumice into the EP, its decomposition rate progressed more slowly. At 800_C, the carbon residue improved as a result of the addition of pumice.

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Authors and Affiliations

İbrahim Kırbaş

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Burdur Mehmet Akif Ersoy University, Department of Electrical and Energy, 15100, Burdur, Turkey

Research on the post-weld explosive hardening of AA7075-T651 friction stir welded butt joints

Robert Kosturek Rafał Lewczuk Janusz Torzewski Marcin Wachowski Piotr Słabik Andrzej Maranda

Bulletin of the Polish Academy of Sciences Technical Sciences | 2023 | 71 | 4 | e145685 | DOI: 10.24425/bpasts.2023.145685

Keywords aluminum friction stir welding explosives mechanical properties post-weld treatment

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Abstract

In this paper, the post-weld explosive hardening of a 5 mm AA7075-T651 plate welded via FSW was performed. To investigate the possibility of increasing FSW joint mechanical properties, the welded plate was explosively treated with four various explosive materials (ammonal, emulsion explosive, FOX-7, and PBX) in two different hardening systems. As part of the investigation, the observations of the surface and macrostructure of the treated plates were described. The obtained microhardness distribution allowed us to register the increase in hardness of the SZ up to 6%, but no increase in hardness of the LHZ was reported. In most cases, the influence of explosive treatment on the mechanical properties of the welded joint was disadvantageous as ultimate tensile strength and ductility were reduced. The only positive effect which was observed is the increase in the value of yield strength up to 27% corresponding to 77 MPa, achieved by explosive materials with detonation velocity below 3000 m/s.

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Authors and Affiliations

Robert Kosturek

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Rafał Lewczuk

Janusz Torzewski

Marcin Wachowski

Piotr Słabik

Andrzej Maranda

Faculty of Mechanical Engineering, Military University of Technology, 2 gen. S. Kaliskiego St., Warsaw, Poland
Łukasiewicz Research Network – Institute of Industrial Organic Chemistry, 6 Annopol St., Warsaw, Poland

Existence, uniqueness and parameter perturbation analysis results of a fractional integro-differential boundary problem

Nan Zhang Lingling Zhang Mercy Ngungu Adejimi Adeniji Emmanuel Addai

Bulletin of the Polish Academy of Sciences Technical Sciences | 2023 | 71 | 4 | e145938 | DOI: 10.24425/bpasts.2023.145938

Keywords existence and uniqueness stability analysis parameter perturbation fractional differential equation integro-differential boundary condition

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Abstract

In the formulation, the existence, uniqueness and stability of solutions and parameter perturbation analysis to Riemann-Liouville fractional differential equations with integro-differential boundary conditions are discussed by the properties of Green’s function and cone theory. First, some theorems have been established from standard fixed point theorems in a proper Banach space to guarantee the existence and uniqueness of positive solution. Moreover, we discuss the Hyers-Ulam stability and parameter perturbation analysis, which examines the stability of solutions in the presence of small changes in the equation main parameters, that is, the derivative order η, the integral order β of the boundary condition, the boundary parameter ξ , and the boundary value τ. As an application, we present a concrete example to demonstrate the accuracy and usefulness of the proposed work. By using numerical simulation, we obtain the figure of unique solution and change trend figure of the unique solution with small disturbances to occur in different kinds of parameters.

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Authors and Affiliations

Nan Zhang

Lingling Zhang

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ORCID:

Mercy Ngungu

Adejimi Adeniji

Emmanuel Addai

College of Mathematics, Taiyuan University of Technology, 030024, TaiYuan, Shanxi, ChinaCollege of Mathematics, Taiyuan University of Technology, 030024, TaiYuan, Shanxi, China
College of Mathematics, Taiyuan University of Technology, 030024, TaiYuan, Shanxi, China
Human Sciences Research Council (HSRC), South Africa
Tshwane university of Technology, South Africa

Studying the thermo-gas-dynamic process in a muzzle brake compensator

Dung Van Nguyen Viet Quy Bui Dung Thai Nguyen Quyen Si Uong Hieu Tu Truong

Archive of Mechanical Engineering | 2023 | vol. 70 | No 2 | 311-328 | DOI: 10.24425/ame.2023.145584

Keywords thermo-gas dynamic muzzle device muzzle brake compensator automatic gun

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Abstract

To reduce the recoil and improve the stability of small arms, a muzzle brake compensator is attached to the muzzle of the barrel. This device uses the kinetic energy of the powder gas escaping from the bore after the bullet is fired. In this paper, the authors present the determination of the thermo-gas-dynamic model of the operation of a muzzle brake compensator and an example of calculating this type of muzzle device for the AK assault rifle using 7.62x39 mm ammunition. The results of the calculation allowed for obtaining the parameters of the powder gas flow in the process of flowing out of the muzzle device, as well as the change in the momentum of the powder gas's impact on the muzzle device. The model proposed in the article provides the basis for a quantitative evaluation of the effectiveness of using the muzzle device in stabilizing infantry weapons when firing.

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Bibliography

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Authors and Affiliations

Dung Van Nguyen

e-mail:

ORCID:

Viet Quy Bui

e-mail:

ORCID:

Dung Thai Nguyen

e-mail:

ORCID:

Quyen Si Uong

e-mail:

ORCID:

Hieu Tu Truong

e-mail:

ORCID:

Faculty of Special Equipment, Le Quy Don Technical University, Hanoi, Vietnam

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Effects of pumice additions on thermal and mechanical behaviors of epoxy resin

Abstract

Authors and Affiliations

Research on the post-weld explosive hardening of AA7075-T651 friction stir welded butt joints

Abstract

Authors and Affiliations

Existence, uniqueness and parameter perturbation analysis results of a fractional integro-differential boundary problem

Abstract

Authors and Affiliations

Studying the thermo-gas-dynamic process in a muzzle brake compensator

Abstract

Bibliography

Authors and Affiliations