Hailu Shimels | Addis Ababa Science and Technology University (original) (raw)

Papers by Hailu Shimels

Journal of Composites Science

This research work investigates the effects of the concentration and treatment of chopped false b... more This research work investigates the effects of the concentration and treatment of chopped false banana (Ensete ventricosum) fibres on the mechanical properties of a polypropylene matrix. The chopped false banana fibres (FBFs) were modified using Aloe Vera gel following treatment with 5% NaOH for 12 h at room temperature, with 1% acetic acid used to neutralise the remaining NaOH. FBF-reinforced polypropylene composite plates were then manufactured with 10, 20, 30, and 40 wt.% of chopped FBF. The mechanical properties were investigated using the compressive, impact, and three-point bending tests. Regarding the mechanical properties of the FBF-reinforced polypropylene composites, it was found that they have a maximum average compressive strength of 17.2 MPa. A maximum bending strength of 12.109 MPa was found for the Aloe Vera gel-treated composite with 30 wt.% of FBF. The maximum average compressive strength for this composite was 17.19 MPa. A maximum bending strength of 9.97 MPa for u...

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This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to m... more This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to manufacture a particleboard. Two boards were tested; one of the boards was fully manufactured from bamboo and the other one was taken from market, which is mostly utilized by those household factories and other wood product manufacturers who use particleboard, fully manufactured from Eucalyptus tree. The particles were bonded using 10% urea formaldehyde. Compression tests were conducted for the two types of particleboards as per Japanese Industrial standard (JIS A 5908) both under wet and dry conditions. A total number of four samples were taken from each type and tested along the width and length on HUALONG universal testing machine with a loading rate of 10mm/min. During the test the upper surfaces of the specimens were under compression and the lower sides were under tension. The results from both tests have shown that the lowland bamboo can be a good candidate for particleboard manufa...

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Productivity improvement has become an important almost in all mass manufacturing industries, who... more Productivity improvement has become an important almost in all mass manufacturing industries, who really implement various methods in the manufacturing process. Productivity improvement techniques can be applied effectively in enterprises of any size, from one-person companies to corporations with thousands of staff. The majority of the techniques were first seen in mass – production operations but the benefits they can yield in SME are not to be underestimated. Indeed, the absence in SME of many of the rigidities commonly found in large companies make it easier for them to reap the benefits of productivity improvement techniques. Lean thinking and enterprise resource planning systems, it zooms in on productivity improvement techniques. Productivity also applies to service sector and many organizations of these sectors are also implementing various methods to improve their productivity. Manufacturing is becoming the provision of complete service over the whole product life cycle. Th...

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Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

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Damping capacity is a measure of a material's ability which absorb vibration energy by conver... more Damping capacity is a measure of a material's ability which absorb vibration energy by converting into heat energy. Materials which have high damping ability can suppress excessive vibrations to a reasonable limit. Therefore, this paper investigates the damping characteristics of five indigenous wood species (Cordia Africana, Juniperus Procera, Afrocarpus Gracilior, Syzygium Guineense and Acacia Decurrens) found in Ethiopia through analytical, numerical and experimental approaches. The experimental testing was performed using piezoelectric accelerometer in association with LabVIEW for a perfectly clamped-free cantilever beam based on the impact hammer excitation. The damping ratio was computed using logarithmic decrement method from the decay curve measured. Based on the investigation, the damping factor for all species of woods was almost equal to 0.020 at room condition, and it is definitely greater than most other crystalline materials. Thus, wooden materials are better suita...

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IAEME PUBLICATION, 2014

This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to m... more This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to manufacture a particleboard. Two boards were tested; one of the boards was fully manufactured from bamboo and the other one was taken from market, which is mostly utilized by those household factories and other wood product manufacturers who use particleboard, fully manufactured from Eucalyptus tree. The particles were bonded using 10% urea formaldehyde. Compression tests were conducted for the two types of particleboards as per Japanese Industrial standard (JIS A 5908) both under wet and dry conditions. A total number of four samples were taken from each type and tested along the width and length on HUALONG universal testing machine with a loading rate of 10mm/min. During the test the upper surfaces of the specimens were under compression and the lower sides were under tension. The results from both tests have shown that the lowland bamboo can be a good candidate for particleboard manufa...

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Most of structural topology optimization problems have been formulated and solved to either minim... more Most of structural topology optimization problems have been formulated and solved to either minimize compliance or weight of a structure under volume or stress constraints, respectively. Even if, a lot of researches are conducted on these two formulation techniques separately, there is no clear comparative study between the two approaches. This paper intends to compare these formulation techniques, so that an end user or designer can choose the best one based on the problems they have. Benchmark problems under the same boundary and loading conditions are defined, solved and results are compared based on these formulations. Simulation results shows that the two formulation techniques are dependent on the type of loading and boundary conditions defined. Maximum stress induced in the design domain is higher when the design domains are formulated using compliance based formulations. Optimal layouts from compliance minimization formulation has complex layout than stress based ones which ...

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Journal of Composites Science

This research work investigates the effects of the concentration and treatment of chopped false b... more This research work investigates the effects of the concentration and treatment of chopped false banana (Ensete ventricosum) fibres on the mechanical properties of a polypropylene matrix. The chopped false banana fibres (FBFs) were modified using Aloe Vera gel following treatment with 5% NaOH for 12 h at room temperature, with 1% acetic acid used to neutralise the remaining NaOH. FBF-reinforced polypropylene composite plates were then manufactured with 10, 20, 30, and 40 wt.% of chopped FBF. The mechanical properties were investigated using the compressive, impact, and three-point bending tests. Regarding the mechanical properties of the FBF-reinforced polypropylene composites, it was found that they have a maximum average compressive strength of 17.2 MPa. A maximum bending strength of 12.109 MPa was found for the Aloe Vera gel-treated composite with 30 wt.% of FBF. The maximum average compressive strength for this composite was 17.19 MPa. A maximum bending strength of 9.97 MPa for u...

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This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to m... more This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to manufacture a particleboard. Two boards were tested; one of the boards was fully manufactured from bamboo and the other one was taken from market, which is mostly utilized by those household factories and other wood product manufacturers who use particleboard, fully manufactured from Eucalyptus tree. The particles were bonded using 10% urea formaldehyde. Compression tests were conducted for the two types of particleboards as per Japanese Industrial standard (JIS A 5908) both under wet and dry conditions. A total number of four samples were taken from each type and tested along the width and length on HUALONG universal testing machine with a loading rate of 10mm/min. During the test the upper surfaces of the specimens were under compression and the lower sides were under tension. The results from both tests have shown that the lowland bamboo can be a good candidate for particleboard manufa...

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Productivity improvement has become an important almost in all mass manufacturing industries, who... more Productivity improvement has become an important almost in all mass manufacturing industries, who really implement various methods in the manufacturing process. Productivity improvement techniques can be applied effectively in enterprises of any size, from one-person companies to corporations with thousands of staff. The majority of the techniques were first seen in mass – production operations but the benefits they can yield in SME are not to be underestimated. Indeed, the absence in SME of many of the rigidities commonly found in large companies make it easier for them to reap the benefits of productivity improvement techniques. Lean thinking and enterprise resource planning systems, it zooms in on productivity improvement techniques. Productivity also applies to service sector and many organizations of these sectors are also implementing various methods to improve their productivity. Manufacturing is becoming the provision of complete service over the whole product life cycle. Th...

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Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

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Bookmarks Related papers MentionsView impact

Damping capacity is a measure of a material's ability which absorb vibration energy by conver... more Damping capacity is a measure of a material's ability which absorb vibration energy by converting into heat energy. Materials which have high damping ability can suppress excessive vibrations to a reasonable limit. Therefore, this paper investigates the damping characteristics of five indigenous wood species (Cordia Africana, Juniperus Procera, Afrocarpus Gracilior, Syzygium Guineense and Acacia Decurrens) found in Ethiopia through analytical, numerical and experimental approaches. The experimental testing was performed using piezoelectric accelerometer in association with LabVIEW for a perfectly clamped-free cantilever beam based on the impact hammer excitation. The damping ratio was computed using logarithmic decrement method from the decay curve measured. Based on the investigation, the damping factor for all species of woods was almost equal to 0.020 at room condition, and it is definitely greater than most other crystalline materials. Thus, wooden materials are better suita...

Bookmarks Related papers MentionsView impact

IAEME PUBLICATION, 2014

This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to m... more This paper evaluates the utilization of Ethiopian lowland bamboo or Oxytenanthera abyssinica to manufacture a particleboard. Two boards were tested; one of the boards was fully manufactured from bamboo and the other one was taken from market, which is mostly utilized by those household factories and other wood product manufacturers who use particleboard, fully manufactured from Eucalyptus tree. The particles were bonded using 10% urea formaldehyde. Compression tests were conducted for the two types of particleboards as per Japanese Industrial standard (JIS A 5908) both under wet and dry conditions. A total number of four samples were taken from each type and tested along the width and length on HUALONG universal testing machine with a loading rate of 10mm/min. During the test the upper surfaces of the specimens were under compression and the lower sides were under tension. The results from both tests have shown that the lowland bamboo can be a good candidate for particleboard manufa...

Bookmarks Related papers MentionsView impact

Most of structural topology optimization problems have been formulated and solved to either minim... more Most of structural topology optimization problems have been formulated and solved to either minimize compliance or weight of a structure under volume or stress constraints, respectively. Even if, a lot of researches are conducted on these two formulation techniques separately, there is no clear comparative study between the two approaches. This paper intends to compare these formulation techniques, so that an end user or designer can choose the best one based on the problems they have. Benchmark problems under the same boundary and loading conditions are defined, solved and results are compared based on these formulations. Simulation results shows that the two formulation techniques are dependent on the type of loading and boundary conditions defined. Maximum stress induced in the design domain is higher when the design domains are formulated using compliance based formulations. Optimal layouts from compliance minimization formulation has complex layout than stress based ones which ...

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