scholarly journals Impact of Wetting and Drying Cycles on the Mechanical Properties and Microstructure of Vegetation-growing Concrete

2021 ◽  
Vol 20 (4) ◽  
Author(s):  
Xiaole Huang ◽  
Wennian Xu ◽  
Yu Ding ◽  
Dong Xia ◽  
Shiyuan Xiong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Structural Damage ◽  
Mechanical Performance ◽  
Sem Analysis ◽  
Influential Factors ◽  
Linear Functions ◽  
Experimental Program ◽  
Widespread Application ◽  
Wetting And Drying ◽  
Wetting And Drying Cycles

Vegetation-growing Concrete (VC), as a new type of cemented soil, is usually used for plants growing on the surface of high and steep rocky slopes. With the widespread application of VC substrate, a pressing problem arises to ensure its durability under wetting and drying conditions. To explore the greatest possible impact on the mechanical properties and microstructure features of VC substrate, an experimental program including triaxial test, SEM analysis, and ultrasonic testing was implemented. The results showed that wetting and drying cycles can significantly decrease more than 40-percent of peak strength, 60-percent of residual strength, and 50-percent of cohesion for VC substrate under ultimate conditions. The fundamental cause of reduction in mechanical performance was found to be the weakening of the bond between soil particles. And it was discovered that structural damage increased as the number of wetting and drying cycles increased but at a slower rate. Based on the tested results, linear functions between the loss extent parameters of mechanical performance and the structural damage variable were established for the VC substrate. Finally, the action mechanisms of wetting and drying cycles for VC substrate were discussed, and the main influential factors were proposed.

scholarly journals Influence of Alkali Treatment on the Microstructure and Mechanical Properties of Coir and Abaca Fibers

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2636
Author(s):  
Petr Valášek ◽  
Miroslav Müller ◽  
Vladimír Šleger ◽  
Viktor Kolář ◽  
Monika Hromasová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Alkali Treatment ◽  
Fiber Surface ◽  
Cellulose Fibers ◽  
Sem Analysis ◽  
Experimental Program ◽  
Time Interval ◽  
The European Union ◽  
Vegetable Fibers

Composite materials with natural fillers have been increasingly used as an alternative to synthetically produced materials. This trend is visible from a representation of polymeric composites with natural cellulose fibers in the automotive industry of the European Union. This trend is entirely logical, owing to a preference for renewable resources. The experimental program itself follows pronounced hypotheses and focuses on a description of the mechanical properties of untreated and alkali-treated natural vegetable fibers, coconut and abaca fibers. These fibers have great potential for use in composite materials. The results and discussion sections contribute to an introduction of an individual methodology for mechanical property assessment of cellulose fibers, and allows for a clear definition of an optimal process of alkalization dependent on the content of hemicellulose and lignin in vegetable fibers. The aim of this research was to investigate the influence of alkali treatment on the surface microstructure and tensile properties of coir and abaca fibers. These fibers were immersed into a 5% solution of NaOH at laboratory temperature for a time interval of 30 min, 1 h, 2 h, 3 h, 6 h, 12 h, 24 h, and 48 h, rinsed and dried. The fiber surface microstructures before and after the alkali treatment were evaluated by SEM (scanning electron microscopy). SEM analysis showed that the alkali treatment in the NaOH solution led to a gradual connective material removal from the fiber surface. The effect of the alkali is evident from the visible changes on the surface of the fibers.

Effects of wetting and drying cycles on mechanical properties of pyroclastic soils

CATENA ◽  
2017 ◽  
Vol 156 ◽  
pp. 113-123 ◽  
Author(s):  
Antonio Pasculli ◽  
Nicola Sciarra ◽  
Luigi Esposito ◽  
Amedeo Wolfango Esposito
Keyword(s):  
Mechanical Properties ◽  
Wetting And Drying ◽  
Pyroclastic Soils ◽  
Wetting And Drying Cycles

Mechanical Performance and Fracture Behavior of Recycled AA6061-T6 Alloy Melted from Aluminium Chips

2017 ◽  
Vol 7 (1) ◽  
pp. 1-17
Author(s):  
Naveed Akhtar ◽  
Razzaq Ahmed ◽  
Muhammad Arfan ◽  
Muhammad Noshad Ali
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compounds ◽  
Fracture Behavior ◽  
Mechanical Performance ◽  
Sem Analysis ◽  
Reverberatory Furnace ◽  
Molten Bath ◽  
Furnace Charge ◽  
Mixed Nature

Aluminium chips were re-melted under the molten bath in a gas fired reverberatory furnace and superior quality recycled AA6061-T6 alloy was synthesized. The chips were added 5 to 20% by weight in the recycled alloy. The furnace charge included clean scrap of the same alloy (AA6061) along with the machining chips or tunings of mixed nature. The chips used in this study were mostly generated from lath/bore operations carried on homogenized billets. The fabricated alloy of each heat was characterized for microstructures, mechanical properties and fracture behavior. The results showed that the metallurgical and mechanical performance of the recycled alloy was comparable to the primary alloy. However, SEM analysis of the recycled alloy revealed a sizeable amount of Fe and Si containing intermetallic compounds such as AlFeSi, AlFeMg, and AlSiMg phases.

Characterization of discontinuous carbon fiber liquid molded PA-6 composites via strategic placement of additional reinforcements

2018 ◽  
Vol 37 (22) ◽  
pp. 1335-1345 ◽  
Author(s):  
Siddhartha Brahma ◽  
Vikas Patel ◽  
Selvum Pillay ◽  
Haibin Ning ◽  
Vinoy Thomas
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Surface Area ◽  
Mechanical Characterization ◽  
Mechanical Performance ◽  
Total Surface Area ◽  
Sem Analysis ◽  
Average Increase ◽  
Similar Increase

The flexibility of processing PA6-based discontinuous carbon fiber panels using vacuum-assisted resin transfer molding was studied. The ease of incorporating various reinforcements namely baseline, tow in the center of preform, fabric in the center of preform and fabric on the outside as skin was investigated. Mechanical characterization was conducted on all the variations made. There was an average increase of about 3%, 20% and 47% in the tensile properties of tow in the center, fabric in the center and fabric on the outside as skin, respectively, as compared to the baseline. A similar increase in properties was noticed in its flexural and impact strength. The data showed a correlation between the mechanical properties and the total surface area of additional reinforcements used. As the surface area of the reinforcement increased, the mechanical properties increased as well. It also showed that reinforcements on the surface of the preform as a skin performed the best. DMA analysis showed the effect of reinforcement on the storage modulus and tan delta across temperatures ranging from 30°C to 150°C. SEM analysis showed that the fibers and the additional reinforcements were coated with PA6 which translated into consistent mechanical performance.

scholarly journals Experimental Investigation of Wavy-Lap Bonds with Natural Cotton Fabric Reinforcement under Cyclic Loading

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2872
Author(s):  
Viktor Kolář ◽  
Miroslav Müller ◽  
Martin Tichý ◽  
Rajesh Kumar Mishra ◽  
Petr Hrabě ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cyclic Loading ◽  
Cotton Fabric ◽  
Mechanical Performance ◽  
Matrix Material ◽  
Safety Evaluation ◽  
Positive Influence ◽  
Sem Analysis ◽  
Adhesive Bonds ◽  
Fabric Surface

This study is focused on the mechanical properties and service life (safety) evaluation of hybrid adhesive bonds with shaped overlapping geometry (wavy-lap) and 100% natural cotton fabric used as reinforcement under cyclic loading using various intensities. Cyclic loading were implemented between 5–50% (267–2674 N) and 5–70% (267–3743 N) from the maximum strength (5347 N) measured by static tensile test. The adhesive bonds were loaded by 1000 cycles. The test results demonstrated a positive influence of the used reinforcement on the mechanical properties, especially during the cyclic loading. The adhesive bonds Tera-Flat withstood the cyclic load intensity from 5–70% (267–3743 N). The shaped overlapping geometry (wavy-lap bond) did not have any positive influence on the mechanical performance, and only the composite adhesive bonds Erik-WH1 and Tera-WH1 withstood the complete 1000 cycles with cyclic loading values between 5–50% (267–2674 N). The SEM analysis results demonstrated a positive influence on the fabric surface by treatment with 10% NaOH aqueous solution. The unwanted compounds (lignin) were removed. Furthermore, a good wettability has been demonstrated by the bonded matrix material. The SEM analysis also demonstrated micro-cracks formation, with subsequent delamination of the matrix/reinforcement interface caused by cyclic loading. The experimental research was conducted for the analysis of hybrid adhesive bonds using curved/wavy overlapping during both static and cyclic loading.

Enhanced Durability of Graphene-Based Epoxy Films

2019 ◽  
Vol 813 ◽  
pp. 279-284
Author(s):  
Carlo Naddeo ◽  
Liberata Guadagno ◽  
Roberto Pantani ◽  
Vito Speranza ◽  
Annalisa Acquesta ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Beneficial Effect ◽  
Morphological Feature ◽  
Mechanical Performance ◽  
Oxidative Degradation ◽  
Film Surface ◽  
Sem Analysis ◽  
Polymeric Films ◽  
Strong Decrease ◽  
Nanoscale Level

Graphene-based nanoparticles are suitable to enhance toughness related to impact, fracture and fatigue of epoxy nanocomposites to make them able to meet industrial requirements. The increase in the mechanical performance of graphene-based films is well known in the literature. This paper highlights an additional beneficial effect of graphene-based nanoparticles, which is related to the increase of the photooxidative resistance of polymeric films. Graphene Nanoplatelets (GNPs) have been incorporated, at different weight percentages, in the epoxy films. Unfilled and nanofilled films (30 ± 1.5 μm thick) have been subjected to the accelerated photo-oxidative degradation by exposing them to UV-A radiation (295–380 nm). AFM-Harmonix modulus maps at the micro and nanoscale level have been detected to investigate the effect of graphene nanoparticle on the mechanical properties of untreated and UV treated unfilled and nanofilled samples. SEM analysis has been used to analyse the effect of graphene on morphological features of the film surface. UV irradiation determines relevant damages of the mechanical properties and morphological feature of the unfilled sample. The experiments carried out on the nanofilled films show that GNPs, dispersed in the epoxy-based films, determine a strong decrease in the entity of the damages of the film surfaces.

Microstructure and Mechanical Properties of AISI 8620 Steel Processed by ECAP

2014 ◽  
Vol 1611 ◽  
pp. 89-94
Author(s):  
Diana M. Marulanda ◽  
Jair G. Cortés ◽  
Marco A. Pérez ◽  
Gabriel García
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Equivalent Strain ◽  
Sem Analysis ◽  
Structure Evolution ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Angular Pressing ◽  
Before And After

ABSTRACTThe aim of this work is to process by equal channel angular pressing (ECAP) a low carbon – triple-alloyed steel containing 0.2% C, 0.5% Cr, 0.6% Ni, 0.2% Mo and 0.8 Mo. The process is performed at room temperature for up to four passes using route Bc with an equivalent strain of ∼0.6 after a single pass. Structure evolution before and after deformation is studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD) and mechanical properties are assessed by microhardness and tensile testing. A significant improvement of the mechanical properties is found with increasing number of ECAP passes. Micro-hardness increases from 216 HV for the initial sample to 302 HV after four passes and tensile strength increases to 1200 MPa compared with 430 MPa prior to ECAP. X-ray diffraction and SEM analysis show changes in the original ferritic-perlitic structure through ferrite grain refinement and the deformation of perlite. This nickel-chromium-molybdenum alloy is used in manufacturing as gear material, and when it is hardened and formed through carburizing or boronizing it can be used to make hard-wearing machine parts. However, the ECAP process has not been used to harden this steel and to change its structure to obtain better mechanical performance.

Influence of an Elevated Temperature Environment on the Tensile Mechanical Properties of a 3D Printed Thermoplastic Polymer

2019 ◽  
Author(s):  
Jose E. Torres ◽  
Otito N. Onwuzurike ◽  
Amber J. W. McClung ◽  
Juan D. Ocampo
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Mechanical Testing ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Material Behavior ◽  
Experimental Program ◽  
Thermoplastic Polymer ◽  
3D Printed ◽  
Property Changes

Abstract The purpose of this study is to examine the effects of the environment on 3D printed Polylactic Acid (PLA), a biodegradable thermoplastic polymer. The experimental program was specifically designed to explore the influence of print temperature and aging temperature on the mechanical performance of the printed material. Printing at the elevated temperatures (30–40°C) resulted in slight mechanical property changes. In order to understand which of the changes could also be caused by simply storing the materials at the elevated temperature, samples were printed at 25°C and subsequently aged (at 30–45°C) before mechanical testing. All mechanical testing was performed in standard laboratory temperature on an MTS Criterion. All of the mechanical properties were not greatly altered by printing or aging at elevated temperatures, suggesting that printing and using in extreme weather environments could be reasonable. The yield stress is not affected by storage at elevated temperatures, but is increased (or enhanced) by printing at elevated temperatures. The maximum stress is increased (or enhanced) by both aging and printing at elevated temperatures, but is accompanied by a large reduction in strain capacity. Changes that are observed in mechanical properties will be incorporated in future material models to accurately capture material behavior.

scholarly journals Some mechanical properties of aggregates of top soils from the IJsselmeer polders. 2. Remoulded soil aggregates and the effects of wetting and drying cycles.

1984 ◽  
Vol 32 (3) ◽  
pp. 215-227 ◽  
Author(s):  
A.R. Dexter ◽  
B. Kroesbergen ◽  
H. Kuipers
Keyword(s):  
Mechanical Properties ◽  
Organic Matter Content ◽  
Clay Content ◽  
Matter Content ◽  
Undisturbed Soil ◽  
Wetting And Drying ◽  
Wetting And Drying Cycles ◽  
Remoulded Soil ◽  
Soil Clay ◽  
Soil Clay Content

The mechanical properties of remoulded samples of eight soils from the IJsselmeer polders were investigated. The Atterberg (Plastic and Liquid) Limits were positively correlated with the soil clay content, but were not significantly correlated with the organic matter content. Artificial aggregates of the remoulded soil age-hardened when moist. The tensile strength of artificial aggregates was positively correlated with the soil clay content and negatively correlated with the porosity. Friability of the dried, remoulded soil was much lower than that of natural, undisturbed soil. Factors affecting the rates of wetting and drying of aggregates in the laboratory were examined in detail. Wetting resulted in mellowing (or softening) of artificial aggregates. Mellowing was investigated as a function of the potential of the source of water causing the wetting. Multiple wetting and drying cycles may result in increased mellowing or in no mellowing depending on the water potential. New terminology is introduced to facilitate discussion of these phenomena. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Sign in / Sign up

Export Citation Format

Share Document