The feasibility of vibration analysis as a mechanism of failure analysis in failure investigations and root cause analysis
- Authors: Human, Etienne
- Date: 2012-07-31
- Subjects: Vibration , Structural dynamics , Structural analysis (Engineering) , Mechanics, Applied , System failures (Engineering)
- Type: Thesis
- Identifier: uj:8872 , http://hdl.handle.net/10210/5339
- Description: M.Phil. , “Failure is one of the unfortunate facts of life”. This is the very first statement in the book by Coetzee (1998). This statement is unfortunately true, leading to the fact that failure is a reality, to be dealt with. Dealing with it in a proactive way will provide warnings of an approaching failure. Dealing with it in a reactive way will go through the “surprising pain” of an unexpected breakdown or downtime. In both cases the source of failure must be known to prevent it from happening again. Root Cause Analysis (RCA) is a structured method of determining the reason (root cause) of a failure. On the other hand, Vibration Analysis is one of the best known methods of condition monitoring and has the capability to indicate a reason for failure, although not necessarily the root cause or causes. The objective of this dissertation is to investigate the possibility to combine the RCA method with Vibration Analysis as forensic science to improve the success of finding root causes and their solutions.
- Full Text:
- Authors: Human, Etienne
- Date: 2012-07-31
- Subjects: Vibration , Structural dynamics , Structural analysis (Engineering) , Mechanics, Applied , System failures (Engineering)
- Type: Thesis
- Identifier: uj:8872 , http://hdl.handle.net/10210/5339
- Description: M.Phil. , “Failure is one of the unfortunate facts of life”. This is the very first statement in the book by Coetzee (1998). This statement is unfortunately true, leading to the fact that failure is a reality, to be dealt with. Dealing with it in a proactive way will provide warnings of an approaching failure. Dealing with it in a reactive way will go through the “surprising pain” of an unexpected breakdown or downtime. In both cases the source of failure must be known to prevent it from happening again. Root Cause Analysis (RCA) is a structured method of determining the reason (root cause) of a failure. On the other hand, Vibration Analysis is one of the best known methods of condition monitoring and has the capability to indicate a reason for failure, although not necessarily the root cause or causes. The objective of this dissertation is to investigate the possibility to combine the RCA method with Vibration Analysis as forensic science to improve the success of finding root causes and their solutions.
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Assessment of structural quality of houses delivered through the people's housing process in South Africa
- Authors: Ogunfiditimi, Olaosebikan
- Date: 2010-03-10T06:20:26Z
- Subjects: Housing , Housing policy , Structural analysis (Engineering) , Engineering standards , Construction industry quality control , Gauteng (South Africa)
- Type: Thesis
- Identifier: uj:6652 , http://hdl.handle.net/10210/3059
- Description: M.Tech. , South African government is one of the countries in the world that has delivered the highest number of houses to the poor through various delivery mechanisms to fulfill her vision to adequate housing for all as reflected in the National Housing Policy framework. Since 1994, about One Million Eight Hundred and Seventy Seven Thousand Nine Hundred and Fifty Eight (1 877 958) houses has been delivered. People’s Housing Process is a state-assisted, self help housing programme and about 3% of the total houses built were delivered through the PHP housing delivery programme. The Government’s goal is, subject to fiscal affordability, to increase housing delivery on a sustainable basis to a peak level of 350 000 units per annum until the housing backlog is overcome (South Africa’s National Housing code policy, 2000:5). The government focused on quantitative housing delivery with qualitative shortcomings. However the focus has now shifted to the quality of the end product delivered. Defects in houses manifest themselves primarily through cracking, dampness, detachment, and water leakages. Defects may be patent or latent, and could be discovered through checking, observations and tests. This research work is a study of structural qualities of houses delivered through PHP. The study investigated the causes of structural inadequacies in PHP houses focusing in the Gauteng Province of South Africa. The findings show that different types of structural defects occurred in houses delivered through PHP scheme, these defects include roof leakages, cracks in walls, wall not being straight and defects in roof trusses. The cause of these defects was as a result of poor quality control mechanism put in place by the Department of Housing.
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- Authors: Ogunfiditimi, Olaosebikan
- Date: 2010-03-10T06:20:26Z
- Subjects: Housing , Housing policy , Structural analysis (Engineering) , Engineering standards , Construction industry quality control , Gauteng (South Africa)
- Type: Thesis
- Identifier: uj:6652 , http://hdl.handle.net/10210/3059
- Description: M.Tech. , South African government is one of the countries in the world that has delivered the highest number of houses to the poor through various delivery mechanisms to fulfill her vision to adequate housing for all as reflected in the National Housing Policy framework. Since 1994, about One Million Eight Hundred and Seventy Seven Thousand Nine Hundred and Fifty Eight (1 877 958) houses has been delivered. People’s Housing Process is a state-assisted, self help housing programme and about 3% of the total houses built were delivered through the PHP housing delivery programme. The Government’s goal is, subject to fiscal affordability, to increase housing delivery on a sustainable basis to a peak level of 350 000 units per annum until the housing backlog is overcome (South Africa’s National Housing code policy, 2000:5). The government focused on quantitative housing delivery with qualitative shortcomings. However the focus has now shifted to the quality of the end product delivered. Defects in houses manifest themselves primarily through cracking, dampness, detachment, and water leakages. Defects may be patent or latent, and could be discovered through checking, observations and tests. This research work is a study of structural qualities of houses delivered through PHP. The study investigated the causes of structural inadequacies in PHP houses focusing in the Gauteng Province of South Africa. The findings show that different types of structural defects occurred in houses delivered through PHP scheme, these defects include roof leakages, cracks in walls, wall not being straight and defects in roof trusses. The cause of these defects was as a result of poor quality control mechanism put in place by the Department of Housing.
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Eaves connections of double-bay portal frames
- Authors: Tshuma, Brighton
- Date: 2015
- Subjects: Structural engineering , Structural analysis (Engineering) , Structural frames , Building, Iron and steel , Building, Stone
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213372 , uj:21145
- Description: Abstract: Tests to determine the structural capacity, failure modes and the economy of the eaves region of double-bay portal frames made from cold-formed lipped channels connected back to back at the eaves joint are presented. Two double-bay portal frame eaves joint configurations, namely; Eaves Connection Type 1 (ECT-1) and Eaves Connection Type 2 (ECT-2) are investigated. In ECT-1, two rafters are connected to the column back-to-back with one rafter connected to the column at a lower level than the other while, in ECT-2, two rafters are connected to the column at the same level through a hot-rolled steel gusset plate. Variables in the frames include the width of the channel flanges, strength of the channels, number of bolts, and thickness of the hot-rolled gusset plate. The joints are subjected to equal loads applied through pins at points of contraflexure until failure. Failure modes and experimental results are observed, recorded and analysed. A comparison between theoretical and experimental results is drawn up and analysed. In all the tested structures (ECT-1 and ECT-2), the cold-formed channels failed but the joints did not fail. Local buckling in the compression zone of the web and flange of the channels, bolt-bearing deformations and lateral deflection of gusset plates (in ECT-2 only) are the three modes of failure which were observed. Local buckling in the compression zone of the web and flange of the channels was the initial and ultimate failure mode in all structures. The moment-curvature graphs show that plasticity could not be achieved in both connections (ECT-1 and ECT-2). The unfactored resistances of the channels are not achieved by all the joints because of local buckling and bolt-bearing deformation failure. Both theoretical and experimental results show that the two investigated joints are semi-rigid and partial-strength joints since they possess some degree of rotational stiffness and moment capacity, but are insufficiently stiff to develop full continuity and unable to achieve full moment capacity of the connected members at the eaves joint. Furthermore, the investigation shows that ECT-1 is the most economic joint from a structural and material cost point of view, compared to ECT-2 joints. However, ECT-2 joints are... , M.Phil. (Civil Engineering)
- Full Text:
- Authors: Tshuma, Brighton
- Date: 2015
- Subjects: Structural engineering , Structural analysis (Engineering) , Structural frames , Building, Iron and steel , Building, Stone
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213372 , uj:21145
- Description: Abstract: Tests to determine the structural capacity, failure modes and the economy of the eaves region of double-bay portal frames made from cold-formed lipped channels connected back to back at the eaves joint are presented. Two double-bay portal frame eaves joint configurations, namely; Eaves Connection Type 1 (ECT-1) and Eaves Connection Type 2 (ECT-2) are investigated. In ECT-1, two rafters are connected to the column back-to-back with one rafter connected to the column at a lower level than the other while, in ECT-2, two rafters are connected to the column at the same level through a hot-rolled steel gusset plate. Variables in the frames include the width of the channel flanges, strength of the channels, number of bolts, and thickness of the hot-rolled gusset plate. The joints are subjected to equal loads applied through pins at points of contraflexure until failure. Failure modes and experimental results are observed, recorded and analysed. A comparison between theoretical and experimental results is drawn up and analysed. In all the tested structures (ECT-1 and ECT-2), the cold-formed channels failed but the joints did not fail. Local buckling in the compression zone of the web and flange of the channels, bolt-bearing deformations and lateral deflection of gusset plates (in ECT-2 only) are the three modes of failure which were observed. Local buckling in the compression zone of the web and flange of the channels was the initial and ultimate failure mode in all structures. The moment-curvature graphs show that plasticity could not be achieved in both connections (ECT-1 and ECT-2). The unfactored resistances of the channels are not achieved by all the joints because of local buckling and bolt-bearing deformation failure. Both theoretical and experimental results show that the two investigated joints are semi-rigid and partial-strength joints since they possess some degree of rotational stiffness and moment capacity, but are insufficiently stiff to develop full continuity and unable to achieve full moment capacity of the connected members at the eaves joint. Furthermore, the investigation shows that ECT-1 is the most economic joint from a structural and material cost point of view, compared to ECT-2 joints. However, ECT-2 joints are... , M.Phil. (Civil Engineering)
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Experimental and numerical structural performance assessment of a direct fired rotary kiln
- Authors: Tyczynski, Damian Dariusz
- Date: 2018
- Subjects: Kilns, Rotary , Deformations (Mechanics) , Structural analysis (Engineering)
- Language: English
- Type: Masters (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/386496 , http://hdl.handle.net/10210/285853 , uj:30921
- Description: Abstract: Rotary kilns are advanced thermal processing systems which are used to process solid material at elevated temperatures. Rotary kilns operate by holding the processed material at a specific temperature for a specific amount of time. There are two main types of rotary kilns i.e. directly fired and indirectly fired rotary kilns. In directly fired rotary kilns, the process material is in direct contact with the combustion flame and flue gases. On the other hand, for the indirect fired kiln, the process material is in an inert environment, which prevents direct contact with the combustion flame and flue gases. Due to the elevated operating temperatures, complex loading scenarios arise. These may lead to mechanical deformations such as axial distortion, transverse distortion, blistering, necking, banana distortion, misalignment and kinks. These behaviours complicate structural performance assessments of rotary kilns. Furthermore, due to the equipment’s size and harsh working environment, it makes it difficult to conduct structural performance tests to obtain experimental data. Therefore, numerical modelling tools may be applied to optimise the design of the rotary kilns. The main purpose of this work was to develop a numerical model for the structural performance of a direct-fired rotary kiln pilot plant, developed by Drytech International Pty. Ltd, and to validate the model by using experimental data. The main study focused on the stress and stain state of the kiln for three load cases namely (1) when the empty kiln is rotating (2) when the kiln is rotating and loaded without heat and (3) when the kiln is rotating and loaded with heat. Through real time strain measurements, transient response validation data was obtained. The experimentally gathered strain measurements were transformed, and the principal stress and strain state was calculated for each point in time. A validated transient finite element numerical model was then develop using Abaqus CAE. Percentage fill and temperature was varied using the numerical model to determine the influence that these parameters had on the direct-fired rotary kiln pilot plant. The investigation confirmed that the structural behaviour of the direct-fired rotary kiln pilot plant is influenced by fill percentage and temperature i.e. the strain and stress variation is dependent on the response of the kilns structure to different load applications. To further develop the study on direct-fired rotary kilns, full scale experimental data should be gathered from full-scale industrial kilns and validated by the use of a numerical modelling tool such as Abaqus CAE. , M.Ing. (Mechanical Engineering)
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- Authors: Tyczynski, Damian Dariusz
- Date: 2018
- Subjects: Kilns, Rotary , Deformations (Mechanics) , Structural analysis (Engineering)
- Language: English
- Type: Masters (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/386496 , http://hdl.handle.net/10210/285853 , uj:30921
- Description: Abstract: Rotary kilns are advanced thermal processing systems which are used to process solid material at elevated temperatures. Rotary kilns operate by holding the processed material at a specific temperature for a specific amount of time. There are two main types of rotary kilns i.e. directly fired and indirectly fired rotary kilns. In directly fired rotary kilns, the process material is in direct contact with the combustion flame and flue gases. On the other hand, for the indirect fired kiln, the process material is in an inert environment, which prevents direct contact with the combustion flame and flue gases. Due to the elevated operating temperatures, complex loading scenarios arise. These may lead to mechanical deformations such as axial distortion, transverse distortion, blistering, necking, banana distortion, misalignment and kinks. These behaviours complicate structural performance assessments of rotary kilns. Furthermore, due to the equipment’s size and harsh working environment, it makes it difficult to conduct structural performance tests to obtain experimental data. Therefore, numerical modelling tools may be applied to optimise the design of the rotary kilns. The main purpose of this work was to develop a numerical model for the structural performance of a direct-fired rotary kiln pilot plant, developed by Drytech International Pty. Ltd, and to validate the model by using experimental data. The main study focused on the stress and stain state of the kiln for three load cases namely (1) when the empty kiln is rotating (2) when the kiln is rotating and loaded without heat and (3) when the kiln is rotating and loaded with heat. Through real time strain measurements, transient response validation data was obtained. The experimentally gathered strain measurements were transformed, and the principal stress and strain state was calculated for each point in time. A validated transient finite element numerical model was then develop using Abaqus CAE. Percentage fill and temperature was varied using the numerical model to determine the influence that these parameters had on the direct-fired rotary kiln pilot plant. The investigation confirmed that the structural behaviour of the direct-fired rotary kiln pilot plant is influenced by fill percentage and temperature i.e. the strain and stress variation is dependent on the response of the kilns structure to different load applications. To further develop the study on direct-fired rotary kilns, full scale experimental data should be gathered from full-scale industrial kilns and validated by the use of a numerical modelling tool such as Abaqus CAE. , M.Ing. (Mechanical Engineering)
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