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Papers by Maher Kassar
Journal of Structural Engineering-asce, Nov 1, 1992
The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicl... more The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicle collisions are the most common cause of liver injuries, current anthropomorphic test devices are not equipped to predict the risk of sustaining abdominal organ injuries. Consequently, researchers rely on finite element models to assess the potential risk of injury to abdominal organs such as the liver. These models must be validated based on appropriate biomechanical data in order to accurately assess injury risk. This study presents a total of 36 uniaxial unconfined compression tests performed on fresh human liver parenchyma within 48 h of death. Fach specimen was tested once to failure at one of four loading rates (0.012, 0.106, 1.036, and 10.708s'') in order to investigate the effects of loading rate on the compressive failure properties of human liver parenchyma. The results of this study showed that the response of human liver parenchyma is both nonlinear and rate dependent. Specifically, failure stress significantly increased with increased loading rate, while failure strain significantly decreased with increased loading rate. The failure stress and failure strain for all liver parenchyma specimens ranged from-38.9 kPa to-145.9kPa and from-0.48 strain to-1.15 strain, respectively. Overall, this study provides novel biomechanical data that can be used in the development of rate dependent material models and the identification of tissue-level tolerance values, which are critical to the validation of finite element models used to assess injury risk.
Journal of Structural Engineering-asce, Nov 1, 1992
In 1991 one of the authors of this paper coauthored a paper [1] on how to qualify a non-standard ... more In 1991 one of the authors of this paper coauthored a paper [1] on how to qualify a non-standard piping component for ASME B31.1 and B31.3 services. Since that time a number of ASME piping qualification standards have been written or are under development that affect how piping components should be qualified. This paper updates the 1991 paper and uses a non-standard piping component, in this case a mechanical joint, to demonstrate a method to qualify non-standard piping components for ASME non-nuclear and nuclear services. The herein documented testing applies the various more current qualification requirements to meet ASME B31 and Section III, Class 2 and 3 Code service rules. The paper explains the intention of the various Code requirements, outlining the mechanical tests and calculations used to demonstrate ASME Code conformance. This paper also discusses non-traditional piping failure mechanisms, mechanisms other than rupture and fatigue, such as component disassembly due to the...
Journal of Structural Engineering, 1992
Journal of Structural Engineering-asce, Nov 1, 1992
The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicl... more The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicle collisions are the most common cause of liver injuries, current anthropomorphic test devices are not equipped to predict the risk of sustaining abdominal organ injuries. Consequently, researchers rely on finite element models to assess the potential risk of injury to abdominal organs such as the liver. These models must be validated based on appropriate biomechanical data in order to accurately assess injury risk. This study presents a total of 36 uniaxial unconfined compression tests performed on fresh human liver parenchyma within 48 h of death. Fach specimen was tested once to failure at one of four loading rates (0.012, 0.106, 1.036, and 10.708s'') in order to investigate the effects of loading rate on the compressive failure properties of human liver parenchyma. The results of this study showed that the response of human liver parenchyma is both nonlinear and rate dependent. Specifically, failure stress significantly increased with increased loading rate, while failure strain significantly decreased with increased loading rate. The failure stress and failure strain for all liver parenchyma specimens ranged from-38.9 kPa to-145.9kPa and from-0.48 strain to-1.15 strain, respectively. Overall, this study provides novel biomechanical data that can be used in the development of rate dependent material models and the identification of tissue-level tolerance values, which are critical to the validation of finite element models used to assess injury risk.
Journal of Structural Engineering-asce, Nov 1, 1992
In 1991 one of the authors of this paper coauthored a paper [1] on how to qualify a non-standard ... more In 1991 one of the authors of this paper coauthored a paper [1] on how to qualify a non-standard piping component for ASME B31.1 and B31.3 services. Since that time a number of ASME piping qualification standards have been written or are under development that affect how piping components should be qualified. This paper updates the 1991 paper and uses a non-standard piping component, in this case a mechanical joint, to demonstrate a method to qualify non-standard piping components for ASME non-nuclear and nuclear services. The herein documented testing applies the various more current qualification requirements to meet ASME B31 and Section III, Class 2 and 3 Code service rules. The paper explains the intention of the various Code requirements, outlining the mechanical tests and calculations used to demonstrate ASME Code conformance. This paper also discusses non-traditional piping failure mechanisms, mechanisms other than rupture and fatigue, such as component disassembly due to the...
Journal of Structural Engineering, 1992