Ian Grosse | University of Massachusetts Amherst (original) (raw)

Papers by Ian Grosse

The 86th Annual Meeting of the American Association of Physical Anthropologists, New Orleans, 2017

This paper develops a two-stage grey-box modeling approach that combines manufacturing knowledge-... more This paper develops a two-stage grey-box modeling approach that combines manufacturing knowledge-based (white-box) models with statistical (black-box) metamodels to improve model reusability and predictability. A white-box model can use various types of existing knowledge such as physical theory, high fidelity simulation or empirical data to build the foundation of the general model. The residual between a white-box prediction and empirical data can be represented with a black-box model. The combination of the white-box and black-box models provides the parallel hybrid structure of a grey-box. For any new point prediction, the estimated residual from the black-box is combined with white-box knowledge to produce the final grey-box solution. This approach was developed for use with manufacturing processes, and applied to a powder bed fusion additive manufacturing process. It can be applied in other common modeling scenarios. Two illustrative case studies are brought into the work to test this grey-box modeling approach; first for pure mathematical rigor and second for manufacturing specifically. The results of the case studies suggest that the use of grey-box models can lower predictive errors. Moreover, the resulting black-box model that represents any residual is a usable, accurate metamodel.

The 84th Annual Meeting of the American Association of Physical Anthropologists, St. Louis, MO, Mar 1, 2015

Last but not least, I would also like to thank my labmates-Justin, Rui, Lieselle, and Brian for t... more Last but not least, I would also like to thank my labmates-Justin, Rui, Lieselle, and Brian for their companionships during these last few years. A special thanks to my family as well for their love and support.

Additive manufacturing, Nov 1, 2021

Abstract Additive manufacturing (AM) of refractory metals, including tantalum (Ta), is highly val... more Abstract Additive manufacturing (AM) of refractory metals, including tantalum (Ta), is highly valued due to the wide application of these materials in different industrial sectors where outstanding mechanical properties at elevated temperatures are required. Among metal AM processes, newly introduced cold gas-dynamic spray or, more commonly, cold spray (CS) offers a unique opportunity for solid-state consolidation of refractory metals. This research presents the CS process as a method for additive manufacturing of Ta. Following the successful manufacturing of free-standing Ta, an extensive mechanical characterization at the macro and nano levels has been carried out to evaluate the material's structural integrity. Anisotropy in the mechanical properties, which is one of the major concerns in the AM-produced materials, was extensively analyzed at both the macro and nano levels. The produced Ta's resistance against the pre-existing crack was studied by evaluating the far-field J-integral versus the crack extension (J-R curve). The influence of microstructural characteristics and process-induced defects such as pores and micro-cracks on the Ta's mechanical and fracture properties was studied to explain the performance-microstructure linkage. The macro and nanomechanical testing results indicated an elastic modulus and ultimate tensile strength in the range of vacuum-arc melted or electron-beam melted Ta ingots following cold-working. The microstructure analysis demonstrated a mixture of ultrafine grains and highly elongated coarse grains, explaining the CS-produced Ta high strength. Moreover, excellent isotropy in the mechanical properties was observed at both the macro and nano levels. This finding distinguishes the CS process from the laser-based AM process in which mechanical properties highly depend on the build direction. On the other hand, the CS-produced Ta exhibited brittle characteristics during uniaxial tensile loading and ductile behavior during the uniaxial compression test. Also, stable crack growth accompanied by crack branching was observed in the CS-produced Ta. The crack branching and formation of secondary cracks have been identified as the mechanisms retard crack extension. Overall, this research revealed that the CS process is a promising AM technique for producing tantalum-based components.

$Research paper thumbnail of Influence of cold sprayed Cr3C2-Ni coating on fracture characteristics of additively manufactured 15Cr-5Ni stainless steel$

Materials & Design, Oct 1, 2018

Influence of cold sprayed Cr3C2-Ni coating on fracture characteristics of additively manufactured... more Influence of cold sprayed Cr3C2-Ni coating on fracture characteristics of additively manufactured 15Cr-5Ni stainless steel. Jmade (2017),

Journal of Computing and Information Science in Engineering, Mar 19, 2018

Additive manufacturing (AM) offers significant opportunities for product innovation in many field... more Additive manufacturing (AM) offers significant opportunities for product innovation in many fields provided that designers are able to recognize the potential values of AM in a given product development process. However, this may be challenging for design teams without substantial experience with the technology. Design inspiration based on past successful applications of AM may facilitate application of AM even in relatively inexperienced teams. While designs for additive manufacturing (DFAM) methods have experimented with reuse of past knowledge, they may not be sufficient to fully realize AM's innovative potential. In many instances, relevant knowledge may be hard to find, lack context, or simply unavailable. This design information is also typically divorced from the underlying logic of a products' business case. In this paper, we present a knowledge based method for AM design ideation as well as the development of a suite of modular, highly formal ontologies to capture information about innovative uses of AM. This underlying information model, the innovative capabilities of additive manufacturing (ICAM) ontology, aims to facilitate innovative use of AM by connecting a repository of a business and technical knowledge relating to past AM products with a collection of knowledge bases detailing the capabilities of various AM processes and machines. Two case studies are used to explore how this linked knowledge can be queried in the context of a new design problem to identify highly relevant examples of existing products that leveraged AM capabilities to solve similar design problems.

Cold spray (CS) is a relatively new spray coating technology which has opened up a new avenue for... more Cold spray (CS) is a relatively new spray coating technology which has opened up a new avenue for deposition of bulk coatings with a thickness in the millimeter range. The unique bonding mechanism of the CS process facilitates deposition of commercially pure titanium (CP-Ti) on a wide range of substrates including high strength alloys. In this paper we present a multi-stage bond coat deposition process using a mixture of ultra-hard ceramic beads and CP-Ti prior to the top CP-Ti coating deposition to produce a coating layer with promising bond strength. In addition, three combinations of the carrier gas temperature (450, 540, and 550 °C), and pressure (2.5 and 3.8 MPa) were considered for maximizing bond strength. The relationship between bond strength and surface roughness was also examined. The shear test results indicated a significant high bond strength of approximately 195 MPa for the gas pressure of 3.8 MPa and temperature of 450 °C owing to the newly introduced bond coat deposition method. The relatively high bond strength is explained by the beneficial effect of multi-stage bond coat prior to the deposition of the bond coat. The results also indicated a tradeoff between bond strength and obtained surface roughness.

Engineering Fracture Mechanics, Mar 1, 1995

This paper presents a discretization error estimator for displacement-based finite element analys... more This paper presents a discretization error estimator for displacement-based finite element analysis applicable to multi-material bodies such as composites. The proposed method applies specific stress continuity requirement across the intermaterial boundary consistent with physical principles. This approach estimates the discretization error by comparing the discontinuous finite element effective stress function with a smoothed (Co continuous) effective stress function for non-intermaterial boundary elements and with a smoothed pseudo effective stress function for elements which lie on the intermaterial boundary. Examples are presented which illustrate the effectiveness of the multi-material error estimator. The pointwise pseudo effective stress and the L, norm of the estimated stress error are seen to converge with mesh refinement, while the Zienkiewicz and Zhu's error estimator failed to converge for elements on the intermaterial boundary due to the physically admissible stress discontinuities that exist on the intermaterial boundary. NOTATION vector quantity matrix quantity material constitutive matrix Co continuous approximation of effective stress function discontinuous finite element effective stress function nodal effective stress at node element effective stress function element pseudo effective stress function Cauchy stresses transformed into ta coordinate system (i.e. tangential and normal to the intermaterial boundary) Cauchy strains transformed into 1-n coordinate system modulus of elasticity local domain of four elements e, , e, , e, and e,

Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, Mar 16, 2010

Australopithecus africanus is an early hominin (i.e., human relative) believed to exhibit stress-... more Australopithecus africanus is an early hominin (i.e., human relative) believed to exhibit stress-reducing adaptations in its craniofacial skeleton that may be related to the consumption of resistant food items using its premolar teeth. Finite element analyses simulating molar and premolar biting were used to test the hypothesis that the cranium of A. africanus is structurally more rigid than that of Macaca fascicularis, an Old World monkey that lacks derived australopith facial features. Previously generated finite element models of crania of these species were subjected to isometrically scaled loads, permitting a direct comparison of strain magnitudes. Moreover, strain energy (SE) in the models was compared after results were scaled to account for differences in bone volume and muscle forces. Results indicate that strains in certain skeletal regions below

Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, Dec 21, 2014

The African Plio-Pleistocene hominins known as australopiths evolved derived craniodental feature... more The African Plio-Pleistocene hominins known as australopiths evolved derived craniodental features frequently interpreted as adaptations for feeding on either hard, or compliant/tough foods. Among australopiths, Paranthropus boisei is the most robust form, exhibiting traits traditionally hypothesized to produce high bite forces efficiently and strengthen the face against feeding stresses. However, recent mechanical analyses imply that P. boisei may not have been an efficient producer of bite force and that robust morphology in primates is not necessarily strong. Here we use an engineering method, finite element analysis, to show that the facial skeleton of P. boisei is structurally strong, exhibits a strain pattern different from that in chimpanzees (Pan troglodytes) and Australopithecus africanus, and efficiently produces high bite force. It has been suggested that P. boisei consumed a diet of compliant/tough foods like grass blades and sedge pith. However, the blunt occlusal topography of this and other species suggests that australopiths are adapted to consume hard foods, perhaps including grass and sedge seeds. A consideration of evolutionary trends in morphology relating to feeding mechanics suggests that food processing behaviors in gracile australopiths evidently were disrupted by environmental change, perhaps contributing to the eventual evolution of Homo and Paranthropus.

Proceedings of The Royal Society B: Biological Sciences, Jun 8, 2022

Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by deri... more Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by derived traits in their crania hypothesized to strengthen the facial skeleton against feeding loads and increase the efficiency of bite force production. The crania of robust australopiths are further thought to be stronger and more efficient than those of gracile australopiths. Results of prior mechanical analyses have been broadly consistent with this hypothesis, but here we show that the predictions of the hypothesis with respect to mechanical strength are not met: some gracile australopith crania are as strong as that of a robust australopith, and the strength of gracile australopith crania overlaps substantially with that of chimpanzee crania. We hypothesize that the evolution of cranial traits that increased the efficiency of bite force production in australopiths may have simultaneously weakened the face, leading to the compensatory evolution of additional traits that reinforced the facial skeleton. The evolution of facial form in early hominins can therefore be thought of as an interplay between the need to increase the efficiency of bite force production and the need to maintain the structural integrity of the face.

Journal of Engineering Design, Sep 18, 2019

Design for additive manufacturing (DFAM) calls for more complex designs to best utilise unique de... more Design for additive manufacturing (DFAM) calls for more complex designs to best utilise unique design freedoms to improve designs. Conversely, less complex designs are generally more suitable for conventional manufacturing processes due to the higher cost to produce features that are more complex. As additive manufacturing (AM) emerges as an increasingly viable option to produce products beyond initial prototyping, the choice of conventional versus additive manufacturing must occur as early as possible in the design process as this choice can substantially affect how the product is designed. Realising the right decision too late in a design process will lead to wasted design time, increased time to market the product, a functionally inferior design, and/or a costlier product. To address this critical decision, we introduce a Design for any X Manufacturing (DFXM) method to use at early design stages to identify the best process for a given product design in cases where comprehensive current process databases may not yet be available to a designer to screen process choices. This DFXM method customises targeted questions to break down concepts into the key elements while capturing any known disparate process choices within consistent formulations. The method relates any measurable metrics found for any criteria at conceptual design within these formulations to evaluate them accordingly. A technique is introduced to simplify and focus voluminous process capability information toward that needed for this specialised early stage decision. After initial inputs from a designer, an algorithm automatically computes the best process choice as a function of expected order quantity. Three illustrative case studies demonstrate the practical application of this DFXM method in representative design scenarios.

Journal of Human Evolution, 2012

Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpre... more Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpretations regarding the feeding ecology and adaptations of Australopithecus africanus. As part of this debate, the methods used in the mechanical studies have been criticized. In particular, it has been claimed that finite element analysis has been poorly applied to this research question. This paper responds to some of these mechanical criticisms, highlights limitations of dental microwear analysis, and identifies avenues of future research.

The FASEB Journal, Apr 1, 2015

The zygomatic region and lateral orbital wall are important structural components of the primate ... more The zygomatic region and lateral orbital wall are important structural components of the primate craniofacial skeleton, providing attachment for muscles, housing and protecting the eye, and resisti...

Ostrich-like birds (Palaeognathae) show very little taxonomic diversity while their sister taxon ... more Ostrich-like birds (Palaeognathae) show very little taxonomic diversity while their sister taxon (Neognathae) contains roughly 10000 species. The main anatomical differences between the two taxa are in the crania. Palaeognaths lack an element in the bill called the lateral bar that is present in both ancestral theropods and modern neognaths, have thin zones in the bones of the bill, and robust bony elements on the ventral surface of their crania. Here we use a combination of modelling and developmental experiments to investigate the processes that might have led to these differences. Engineering-based finite element analyses indicate that removing the lateral bars from a neognath increases mechanical stress in the upper bill and the ventral elements of the skull, regions that are either more robust or more flexible in palaeognaths. Surgically removing the lateral bar from neognath hatchlings led to similar changes. These results indicate that the lateral bar is load-bearing and suggest that this function was transferred to other bony elements when it was lost in palaeognaths. It is possible that the loss of the load-bearing lateral bar might have constrained diversification of skull morphology in palaeognaths and thus limited taxonomic diversity within the group

The minerals, metals & materials series, 2018

This research work examines the mechanical behavior of 15Cr-5Ni stainless steel parts produced by... more This research work examines the mechanical behavior of 15Cr-5Ni stainless steel parts produced by direct metal laser sintering (DMLS). The main objective of this research is to identify the influence of low-temperature precipitation hardening on tensile properties and fracture toughness of DMLS fabricated specimens. Test specimens were fabricated according to ASTM E8/M8 and ASTM E399 standards using EOS M290 laser sintering machine. Following DMLS specimens were subjected to precipitation hardening for an hour at a temperature of 486 °C. To evaluate the influence of heat treatment on mechanical properties of the DMLS produced parts, tension tests and linear-elastic plane-strain fracture toughness tests were performed at the room temperature. Furthermore, microscopic observation of fractured surface was performed to study the failure mechanisms in more detail. The outcomes indicated that the post-DMLS heat treatment improves mechanical properties in the terms of yield stress, Young’s modulus, and ultimate tensile strength. However, this process has a negligible negative effect on the ductility. Moreover, the fracture toughness test results indicated ductile fracture mechanism in the DMLS produced specimens while the specimens were subjected to precipitation hardening demonstrates brittle fracture.

Advancements in the capabilities of additive manufacturing (AM) have increased its usage as an ap... more Advancements in the capabilities of additive manufacturing (AM) have increased its usage as an appropriate manufacturing process, particularly when the number of parts in an assembly can be significantly reduced, production volumes are low, or geometric complexity is difficult, if not impossible, to obtain through conventional subtractive processes. However, there are many reasons why it is best to not design a given part based on AM technology. The choice of conventional versus AM manufacturing must occur as early as possible in the design process as this choice can substantially affect how the product is designed. Making the wrong decision will lead to wasted design time, increased time to market the product, a functionally inferior design, and/or a costlier product. To address this critical manufacturing decision, we introduce a usable template and a decision making method for manufacturing process selection which is integrated early into the design process (DS-SAM). This work can serve as the logical foundation for a potential holistic and more mathematically rigorous formulation toward a decision making method that could infer design evaluations based on designer inputs. This approach improves early design efficiency and effectiveness by methodically focusing on the key design process elements to optimally compare alternatives earlier in a design process. The benefits and potential cost savings of using the DS-SAM approach are demonstrated by a pair of case studies, and the results are discussed.