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Full-Text Articles in Engineering
A Comparative Study On Representativeness And Stochastic Efficacy Of Miniature Tensile Specimen Testing, Sreekar Karnati, Sriram Praneeth Isanaka, Yunlu Zhang, Frank W. Liou, Jason L. Schulthess
A Comparative Study On Representativeness And Stochastic Efficacy Of Miniature Tensile Specimen Testing, Sreekar Karnati, Sriram Praneeth Isanaka, Yunlu Zhang, Frank W. Liou, Jason L. Schulthess
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this article, a miniature dog bone tensile coupon design was tested against the existing ASTM standard specimen design. Specimens were prepared from commercially sourced austenitic stainless steel 304 alloy, and a defect-ridden additively manufactured 304L alloy was studied. By utilizing a tensile specimen design that is 1/230th volume of the smallest ASTM E8-04 (2016), Standard Test Methods for Tension Testing of Metallic Materials, dog bone specimen, coupled to a digital image correlation (DIC) setup, case studies were performed to compare tensile property measurements and strain field evolution. Whereas yield strength measurements were observed to be similar, post-yield, the ultimate …
Flexible Planar Metamaterials With Tunable Poisson's Ratios, Nicholas Pagliocca, Kazi Zahir Uddin, Ibnaj Anamika Anni, Chen Shen, George Youssef, Behrad Koohbor
Flexible Planar Metamaterials With Tunable Poisson's Ratios, Nicholas Pagliocca, Kazi Zahir Uddin, Ibnaj Anamika Anni, Chen Shen, George Youssef, Behrad Koohbor
Henry M. Rowan College of Engineering Departmental Research
This research reports on the design, fabrication, and multiscale mechanical characterization of flexible, planar mechanical metamaterials with tailorable mechanical properties. The tunable mechanical behavior of the structures is realized through the introduction of orthogonal perforations with different geometric features. Various configurations of the perforations lead to a wide range of Poisson's ratios (from −0.8 to 0.4), load-bearing properties, and energy absorption capacities. The correlations between the configuration of the perforations and the auxetic response of the structures are highlighted through computational and experimental characterizations performed at multiple length scales. It is demonstrated that the local in-plane rotation of the solid …
Characterizing Fiber-Matrix Debond And Fiber Interaction Mechanisms By Full-Field Measurements, Robert Livingston, Behrad Koohbor
Characterizing Fiber-Matrix Debond And Fiber Interaction Mechanisms By Full-Field Measurements, Robert Livingston, Behrad Koohbor
Henry M. Rowan College of Engineering Departmental Research
An experimental approach is developed and utilized to characterize the fiber-matrix interfacial debonding mechanism and its effect on matrix cracking in unidirectional (UD) fiber composites. Local deformation response at the fiber-matrix interface is first studied by analyzing the strain fields developed in the vicinity of macro fibers in single-fiber samples. A practical approach for the identification of normal cohesive behavior at the fiber-matrix interface is presented and implemented in a finite element model that replicates the experimental findings. Fiber-to-fiber interaction, debond formation, and failure mechanisms in multiple fiber systems are then studied by varying the distance and angle between adjacent …
Experimental Methods To Capture Curing Induced Effects In Adhesive Bonded Joints, Akshat Agha, Fadi Abu-Farha
Experimental Methods To Capture Curing Induced Effects In Adhesive Bonded Joints, Akshat Agha, Fadi Abu-Farha
Publications
The rapidly increasing use of structural adhesives, especially in the joining of automotive body structures has motivated various investigations of the effects of adhesive curing process on joints. The automotive-grade structural adhesives require heat curing, which, in the meantime, performs thermal loading on the substrates and causes undesirable effects in the joint. For example, the curing process results in complex residual stresses in the adhesive bond which are detrimental to the performance of the adhesive bond and thereby the automobile body structure, particularly the crashworthiness. To thoroughly evaluate such effects, this paper consists of two parts. The first part presents …
On The Feasibility Of Tailoring Copper-Nickel Functionally Graded Materials Fabricated Through Laser Metal Deposition, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk
On The Feasibility Of Tailoring Copper-Nickel Functionally Graded Materials Fabricated Through Laser Metal Deposition, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this study, pulse‐width modulation of laser power was identified as a feasible means for varying the chemical gradient in copper—nickel‐graded materials. Graded material deposits of 70 wt. %. copper‐30 wt. %. nickel on 100 wt. %. nickel and vice versa were deposited and characterized. The 70/30 copper—nickel weight ratio in the feedstock powder was achieved through blending elemental copper and 96 wt. %. Ni—Delero‐22 alloy. At the dissimilar material interface over the course of four layers, the duty cycle of power was ramped down from a high value to optimized deposition conditions. This change was theorized to influence the …
Vibration Analysis Of Healthy Skin: Toward A Noninvasive Skin Diagnosis Methodology, Rakshita Panchal, Luke Horton, Peyman Poozesh, Javad Baqersad, Mohammadreza Nasiriavanaki
Vibration Analysis Of Healthy Skin: Toward A Noninvasive Skin Diagnosis Methodology, Rakshita Panchal, Luke Horton, Peyman Poozesh, Javad Baqersad, Mohammadreza Nasiriavanaki
Mechanical Engineering Publications
Several noninvasive imaging techniques have been developed to monitor the health of skin and enhance the diagnosis of skin diseases. Among them, skin elastography is a popular technique used to measure the elasticity of the skin. A change in the elasticity of the skin can influence its natural frequencies and mode shapes. We propose a technique to use the resonant frequencies and mode shapes of the skin to monitor its health. Our study demonstrates how the resonant frequencies and mode shapes of skin can be obtained using numerical and experimental analysis. In our study, natural frequencies and mode shapes are …