Influence of Fibre Treatment and Matrix Modification on Mechanical Properties of Flax Fibre Reinforced Mortars after Freeze/Thaw Cycles

2022 ◽  
Author(s):  
Bojan Poletanovic ◽  
Katalin Kopecsko ◽  
Ildikó Merta
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Linseed Oil ◽  
Absorption Capacity ◽  
Flax Fibre ◽  
Energy Absorption Capacity ◽  
Freeze Thaw ◽  
Flax Fibres ◽  
Matrix Modification ◽  
Compressive And Flexural Strengths

The aim of this study was to examine the influence of flax fibre protection with the linseed oil and a matrix modification with cement substitution with metakaolin (in 10wt% and 15wt%) on the mechanical properties of cement-based mortars under severe environmental conditions of freeze/thaw cycles. Cement-based mortars (with the dimension of 40x40x160 mm3) were reinforced by 10mm long discrete flax fibres (Linumusitatissimum) and exposed to 51 freeze/thaw cycles under laboratory condition. Their compressive and flexural strengths, as well as specific energy absorption capacity were measured after freeze/thaw cycles and compared to the results of mortars cured for same time in water. Under freeze/thaw cycles mortars reinforced with linseed oil-treated fibres showed the same range of degradation of the compressive and flexural strengths, however, a more pronounced degradation of energy absorption capacity compared to non-treated fibre reinforced mortars was observed. The matrix modification, by partial cement substitution with metakaolin showed optimistic results under freeze/thaw cycles. The compressive strength when cement was partially substituted with metakaolin (in both dosages) increased whereas the flexural strength was slightly lower in case of 10wt% substitution and markedly lower under higher (15wt%) cement substitution. The most relevant is that the decrease of the energy absorption capacity of the fibre reinforced mortar was completely prevented when cement was substituted with metakaolin. It is shown that the energy absorption of the non-treated fibre reinforced mortars increases by 27% when cement was substituted with metakaolin (both 10wt% and 15wt%).

scholarly journals Static Mechanical Properties of Expanded Polypropylene Crushable Foam

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 249
Author(s):  
Przemysław Rumianek ◽  
Tomasz Dobosz ◽  
Radosław Nowak ◽  
Piotr Dziewit ◽  
Andrzej Aromiński
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Strain Rate ◽  
Energy Absorption ◽  
Experimental Tests ◽  
Absorption Capacity ◽  
Strain Rates ◽  
Foam Density ◽  
Energy Absorption Capacity ◽  
Closed Cell

Closed-cell expanded polypropylene (EPP) foam is commonly used in car bumpers for the purpose of absorbing energy impacts. Characterization of the foam’s mechanical properties at varying strain rates is essential for selecting the proper material used as a protective structure in dynamic loading application. The aim of the study was to investigate the influence of loading strain rate, material density, and microstructure on compressive strength and energy absorption capacity for closed-cell polymeric foams. We performed quasi-static compressive strength tests with strain rates in the range of 0.2 to 25 mm/s, using a hydraulically controlled material testing system (MTS) for different foam densities in the range 20 g/dm3 to 220 g/dm3. The above tests were carried out as numerical simulation using ABAQUS software. The verification of the properties was carried out on the basis of experimental tests and simulations performed using the finite element method. The method of modelling the structure of the tested sample has an impact on the stress values. Experimental tests were performed for various loads and at various initial temperatures of the tested sample. We found that increasing both the strain rate of loading and foam density raised the compressive strength and energy absorption capacity. Increasing the ambient and tested sample temperature caused a decrease in compressive strength and energy absorption capacity. For the same foam density, differences in foam microstructures were causing differences in strength and energy absorption capacity when testing at the same loading strain rate. To sum up, tuning the microstructure of foams could be used to acquire desired global materials properties. Precise material description extends the possibility of using EPP foams in various applications.

Experimental Analysis of Aluminum Alloy Section Bars and their Mortise and Tenon Joints under Bending Load

2011 ◽  
Vol 415-417 ◽  
pp. 2338-2344
Author(s):  
Xin Shen Huang ◽  
Qun Gao ◽  
Zhi Jian Zong
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Energy Absorption ◽  
Experimental Analysis ◽  
Absorption Capacity ◽  
Main Section ◽  
Bending Properties ◽  
Energy Absorption Capacity ◽  
Bending Load ◽  
Mortise And Tenon

Different laid modes of aluminum alloy section bars and their mortise and tenon joints were bending tested, and their mechanical properties were compared, in order to research on the influence that forming a mortise and tenon joint brought to the original bars. Opening a hole laterally and inserting another shorter bar in the hole changed the bending properties and energy absorption capacity of the original bar. In horizontal laid mode, the mortise and tenon joint was weaker than the original bar when bearing bending load, but it was stronger in vertical laid mode. Weld beads of the mortise and tenon joints were strong enough to maintain the structure integrality before the main section bars were destroyed by load.

scholarly journals Mechanische Eigenschaften der Fichte: Experimente zur Analyse von Naturgefahren | Mechanical properties of Norway spruce: Experiments for the analysis of natural hazards

2007 ◽  
Vol 158 (6) ◽  
pp. 166-175 ◽  
Author(s):  
Matthias Kalberer ◽  
Martin Ammann ◽  
Martin Jonsson
Keyword(s):  
Mechanical Properties ◽  
Norway Spruce ◽  
Energy Absorption ◽  
Natural Hazards ◽  
Mechanical Stability ◽  
Wood Quality ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Impact Tests ◽  
Four Point Bending

Among others, the protective effect of the forest against natural hazards is mostly co-determined through the mechanical stability of the trees. Despite this, there is a lack of quantifiable knowledge regarding the mechanical interaction between the trees, the forest and natural hazards. With experiments conducted on spruce trees,and mechanical modelling of trees and tree trunks, the mechanical properties and the energy absorption capacity for a single tree during a rock impact were determined. It was shown that the anchorage properties correlated well with the volume of the tree stem. The four-point bending tests and the dynamic impact tests enabled us to determine the strength of the tree stems. Furthermore, the obtained values for the strength of the tree stems were strongly affected by the wood quality and sometimes deviated substantially from the established material properties of dried wood used for buildings. The behavior of trees when impacted by rocks could be simulated with full-scale impact tests and the energy absorption capacity quantified. These experiments gave important knowledge of how to analyze the interaction between natural hazards, trees and forests,with the focus on Norway spruce. However, to quantify the protection effect of the forest against natural hazards,more experiments on different tree species are required.

Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

2021 ◽  
pp. 146442072199749
Author(s):  
H Geramizadeh ◽  
S Dariushi ◽  
S Jedari Salami
Keyword(s):  
Energy Absorption ◽  
Sandwich Structures ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
The Novel ◽  
Energy Absorption Capacity ◽  
Fused Deposition ◽  
Honeycomb Sandwich ◽  
Out Of Plane ◽  
Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

scholarly journals Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
S. Talebi ◽  
R. Hedayati ◽  
M. Sadighi
Keyword(s):  
Surface Area ◽  
Dynamic Behavior ◽  
Energy Absorption ◽  
Peak Stress ◽  
Absorption Capacity ◽  
Unit Cell ◽  
Lattice Structures ◽  
Energy Absorption Capacity ◽  
Closed Cell ◽  
Unit Cells

AbstractClosed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

Numerical Investigation of Cross-Section on Aluminum A6063 Thin-Walled Structures under Low-Velocity Impact Loading

2014 ◽  
Vol 1019 ◽  
pp. 96-102
Author(s):  
Ali Taherkhani ◽  
Ali Alavi Nia
Keyword(s):  
Energy Absorption ◽  
Cross Section ◽  
Cross Sections ◽  
Peak Load ◽  
Circular Cross Section ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Crush Strength

In this study, the energy absorption capacity and crush strength of cylindrical thin-walled structures is investigated using nonlinear Finite Elements code LS-DYNA. For the thin-walled structure, Aluminum A6063 is used and its behaviour is modeled using power-law equation. In order to better investigate the performance of tubes, the simulation was also carried out on structures with other types of cross-sections such as triangle, square, rectangle, and hexagonal, and their results, namely, energy absorption, crush strength, peak load, and the displacement at the end of tubes was compared to each other. It was seen that the circular cross-section has the highest energy absorption capacity and crush strength, while they are the lowest for the triangular cross-section. It was concluded that increasing the number of sides increases the energy absorption capacity and the crush strength. On the other hand, by comparing the results between the square and rectangular cross-sections, it can be found out that eliminating the symmetry of the cross-section decreases the energy absorption capacity and the crush strength. The crush behaviour of the structure was also studied by changing the mass and the velocity of the striker, simultaneously while its total kinetic energy is kept constant. It was seen that the energy absorption of the structure is more sensitive to the striker velocity than its mass.

Sign in / Sign up

Export Citation Format

Share Document