Abstract: The mechanical response of open-cell metallic foams depends strongly on their hierarchical structure, which ranges from the grain scale, to the scale of individual struts, to the scale of the bulk foam. The objective of this study is to investigate the effect of grain structure on the compressive mechanical response of open-cell metallic foam using a crystal-plasticity finite-element-based framework. Multiple polycrystalline instantiations (overlaid on a foam volume derived from X-ray tomography) are simulated to quantify the grain-size effect on crushing response of investment-cast aluminum foam. The high-fidelity numerical framework captures the deformation mechanisms across multiple length scales and is...
Continue readingML+MD to predict strength of CNT-polymer interface
Abstract Modern aerospace applications require lightweight materials with exceptionally high strength and stiffness. Carbon nanotube (CNT)-reinforced composites have great potential in addressing these requirements. However, one critical factor limiting the potential of CNT-reinforced composites is the limited load transfer capability between CNTs through a polymer matrix, which arises due to low CNT-polymer interfacial shear strength at a molecular scale. While molecular dynamics (MD) simulations can be employed to investigate the CNT-polymer interface, such simulations are computationally expensive. It is thus intractable to explore a sufficiently large design space for interface modifications and optimization using MD simulations alone, motivating the...
Continue readingHigh-fidelity simulations of impact-induce skull fracture in infants
Abstract: Infant skull fractures are common in both accidental and abusive head trauma, but identifying the cause of injury may be challenging without adequate evidence. To better understand the mechanics of infant skull fracture and identify environmental variables that lead to certain skull fracture patterns, we developed an innovative computational framework that utilizes linear elastic fracture mechanics theory to predict skull fracture as a first step to study this problem. The finite-element method and adaptive-remeshing technique were employed to simulate high-fidelity, geometrically explicit crack propagation in an infant skull following impact. In the framework, three modes of stress intensity...
Continue reading
MMM Lab represents at TMS annual meeting
MMM Lab members recently presented work at the TMS Annual Meeting in San Diego, CA. The following presentations included MMM Lab members: Determination of Representative Volume Elements for Small Cracks in Heterogeneous Domains via Convolutional Neural Networks: Karen DeMille, Ashley Spear Predicting Crack Location Using a Radial Distribution Function as a Unique Descriptor of Pore Networks: John Erickson, Aowabin Rahman, Ashley Spear Characterization of Fatigue Short Crack Growth in Rare-earth Magnesium Alloy WE43 using High Energy X-ray Diffraction Microscopy: Duncan Greeley (Univ. of Michigan), Jacob Adams (Univ. of Michigan), Peter Kenesei (Argonne National Laboratory), Ashley Spear, John Allison (Univ. of...
Continue reading
Five talks at ASME IMECE
MMM Lab members (Dr. Nadia Kouraytem, Dillon Watring, Karen DeMille, Jimmy He, and Jiawei Yan) presented their recent research results at the ASME International Mechanical Engineering Congress & Exposition (IMECE) held in our hometown, Salt Lake City. Prof. Spear also sat on a panel aimed at helping new and aspiring faculty members. ...
Continue reading
Seminar at Georgia Tech
Prof. Spear presented work from the MMM Lab in the School of Aerospace Engineering at Georgia Tech on October 17. The talk was entitled Predicting Microstructure-Sensitive Mechanical Behavior of Materials by Integrating Physics-Based Modeling with Machine Learning. The presentation covered research by lab members Kyle Pierson, Aowabin Rahman, and Carl Herriott. Many thanks to the wonderful faculty and students from Georgia Tech AE for fruitful discussions and for attending the seminar!...
Continue reading
Class of 20 Students Participates in the Sandia Fracture Challenge
A recent article in the International Journal of Fracture details the results and experience of a class’ participation in the Third Sandia Fracture Challenge (SFC3). In the spring semester of 2017, 20 University of Utah graduate students who were enrolled in a course on Fatigue and Fracture Mechanics (offered by Prof. Ashley Spear) participated in the Challenge, in which all participants were tasked with predicting ductile fracture in a 3D-printed stainless steel specimen geometry. The participants were provided with data from Sandia National Labs to help calibrate their models and were asked to provide local and global measures from...
Continue readingEffect of build conditions on fatigue properties of AM IN718
Ph.D. student, Dillon Watring, recently published his work on the effect of additive manufacturing parameters on the fatigue-driving mechanisms in AM IN718. Dillon and his collaborators found that build orientation is linked to surface roughness, which is, in turn, linked to fatigue life. For a given build orientation, there is an optimal range of laser-energy density; outside of this range, internal defects like lack-of-fusion and secondary cracking lead to reductions in total fatigue life. To read more, check out the complete manuscript. This work is supported by an NSF CAREER award (CMMI-1752400) and by the DOD Office of Economic...
Continue readingMachine Learning Model Predicts 3D Crack Path
MMM Lab members, Kyle Pierson and Dr. Aowabin Rahman, implemented a convolutional neural network to predict the growth of a 3D crack surface and to quantify the corresponding model uncertainty. The work was supported by the Air Force Office of Scientific Research Young Investigator Program under Agreement No. FA9550-15-1-0172. Click here to access the full article....
Continue reading
We are now on twitter!
The MMM Lab now has a twitter account. For the latest updates from our lab, follow us @MMMLabUtah. ...
Continue reading