A Semi-Empirical Constitutive Model for Post Yield Behavior of Bone in Tension

ASME 2007 Summer Bioengineering Conference ◽

10.1115/sbc2007-176237 ◽

2007 ◽

Author(s):

Huijie Leng ◽

Jeffry S. Nyman ◽

Xuanliang Dong ◽

Michael J. Reyes ◽

Xiaodu Wang

Keyword(s):

Constitutive Model ◽

Material Properties ◽

Bone Fractures ◽

Experimental Studies ◽

Underlying Mechanism ◽

Failure Behavior ◽

Yield Behavior ◽

Clinical Strategies ◽

Semi Empirical ◽

Further Development

Among the material properties that can be assessed through mechanical testing, toughness quantifies the energy required for failure and is therefore most suited for characterizing bone quality. As much of the toughness of bone occurs after yielding, post yield behavior of bone is attracting more and more attention [1, 2]. Although a lot of experimental studies have been conducted on post yield behavior of bone, little efforts have been made to develop constitutive relation for post yield behavior of bone tissues. Elucidating the underlying mechanism of post-yield behavior of bone is critical for further development of clinical strategies to predict and prevent age and disease related bone fractures. In addition, such understanding could help bridge the gap between biology and mechanics of bone since cellular activities are directly related to the ultrastructural architecture and composition of the tissue. Moreover, an accurate constitutive model is always required in numerical modeling and simulating the mechanical behavior of bone under different loading conditions. Based on the results reported in the literature and obtained in our laboratory, this study intends to develop and verify a semi-empirical constitutive model of the post-yield and failure behavior of the cortical bone tissue in tension.

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A Semi-Empirical Elastic-Plastic-Visco-Damage Constitutive Model of Cortical Bone

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19416 ◽

2010 ◽

Author(s):

Qing Luo ◽

Huijie Leng ◽

Rae Acuna ◽

Xuanliang Dong ◽

Qiguo Rong ◽

...

Keyword(s):

Constitutive Model ◽

Mechanical Behavior ◽

Cortical Bone ◽

Bone Fractures ◽

Constitutive Models ◽

Underlying Mechanism ◽

Yield Behavior ◽

Damage Constitutive Model ◽

Semi Empirical ◽

Further Development

Bone quality can be characterized by toughness of bone which quantifies the energy required for failure. As much of the toughness of bone occurs after yielding, elucidating the underlying mechanism of post-yield behavior of bone is critical for further development of clinical strategies to predict and prevent age and disease related bone fractures. However, the underlying mechanism of the post-yield behavior of cortical bone is so far poorly understood, which makes it difficult to establish physically sound constitutive models for cortical bone that could accurately predict the mechanical behavior of the tissue. The absence of the constitutive equations has significantly hindered the application of bone mechanics in solving biomedical problems. Besides, an accurate constitutive model is always required in numerical modeling and simulating the mechanical behavior of bone under different loading conditions. Based on the experimental results obtained in our lab, the objective of this study was to develop and verify a constitutive model of cortical bone under compression, which accounted for damage accumulation, plastic deformation and viscoelastic properties.

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Development of Elastoplastic-Damage Model of AlFeSi Phase for Aluminum Alloy 6061

Metals ◽

10.3390/met11060954 ◽

2021 ◽

Vol 11 (6) ◽

pp. 954

Author(s):

Hailong Wang ◽

Wenping Deng ◽

Tao Zhang ◽

Jianhua Yao ◽

Sujuan Wang

Keyword(s):

Aluminum Alloy ◽

Constitutive Model ◽

Material Properties ◽

Damage Model ◽

Scratch Test ◽

Aluminum Alloy 6061 ◽

Ultra Precision ◽

Simulation Results ◽

Alloy 6061 ◽

Elastoplastic Damage

Material properties affect the surface finishing in ultra-precision diamond cutting (UPDC), especially for aluminum alloy 6061 (Al6061) in which the cutting-induced temperature rise generates different types of precipitates on the machined surface. The precipitates generation not only changes the material properties but also induces imperfections on the generated surface, therefore increasing surface roughness for Al6061 in UPDC. To investigate precipitate effect so as to make a more precise control for the surface quality of the diamond turned Al6061, it is necessary to confirm the compositions and material properties of the precipitates. Previous studies have indicated that the major precipitate that induces scratch marks on the diamond turned Al6061 is an AlFeSi phase with the composition of Al86.1Fe8.3Si5.6. Therefore, in this paper, to study the material properties of the AlFeSi phase and its influences on ultra-precision machining of Al6061, an elastoplastic-damage model is proposed to build an elastoplastic constitutive model and a damage failure constitutive model of Al86.1Fe8.3Si5.6. By integrating finite element (FE) simulation and JMatPro, an efficient method is proposed to confirm the physical and thermophysical properties, temperature-phase transition characteristics, as well as the stress–strain curves of Al86.1Fe8.3Si5.6. Based on the developed elastoplastic-damage parameters of Al86.1Fe8.3Si5.6, FE simulations of the scratch test for Al86.1Fe8.3Si5.6 are conducted to verify the developed elastoplastic-damage model. Al86.1Fe8.3Si5.6 is prepared and scratch test experiments are carried out to compare with the simulation results, which indicated that, the simulation results agree well with those from scratch tests and the deviation of the scratch force in X-axis direction is less than 6.5%.

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Application of feed forward and recurrent neural networks in simulation of left ventricular mechanics

Scientific Reports ◽

10.1038/s41598-020-79191-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yaghoub Dabiri ◽

Alex Van der Velden ◽

Kevin L. Sack ◽

Jenny S. Choy ◽

Julius M. Guccione ◽

...

Keyword(s):

Real Time ◽

Material Properties ◽

In Silico ◽

Prediction Models ◽

Heart Function ◽

Active Material ◽

Experimental Studies ◽

Left Ventricular ◽

Feed Forward ◽

Ventricular Mechanics

AbstractAn understanding of left ventricle (LV) mechanics is fundamental for designing better preventive, diagnostic, and treatment strategies for improved heart function. Because of the costs of clinical and experimental studies to treat and understand heart function, respectively, in-silico models play an important role. Finite element (FE) models, which have been used to create in-silico LV models for different cardiac health and disease conditions, as well as cardiac device design, are time-consuming and require powerful computational resources, which limits their use when real-time results are needed. As an alternative, we sought to use deep learning (DL) for LV in-silico modeling. We used 80 four-chamber heart FE models for feed forward, as well as recurrent neural network (RNN) with long short-term memory (LSTM) models for LV pressure and volume. We used 120 LV-only FE models for training LV stress predictions. The active material properties of the myocardium and time were features for the LV pressure and volume training, and passive material properties and element centroid coordinates were features of the LV stress prediction models. For six test FE models, the DL error for LV volume was 1.599 ± 1.227 ml, and the error for pressure was 1.257 ± 0.488 mmHg; for 20 LV FE test examples, the mean absolute errors were, respectively, 0.179 ± 0.050 for myofiber, 0.049 ± 0.017 for cross-fiber, and 0.039 ± 0.011 kPa for shear stress. After training, the DL runtime was in the order of seconds whereas equivalent FE runtime was in the order of several hours (pressure and volume) or 20 min (stress). We conclude that using DL, LV in-silico simulations can be provided for applications requiring real-time results.

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Effects of infill patterns on the strength and stiffness of 3D printed topologically optimized geometries

Rapid Prototyping Journal ◽

10.1108/rpj-11-2019-0290 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Nadim S. Hmeidat ◽

Bailey Brown ◽

Xiu Jia ◽

Natasha Vermaak ◽

Brett Compton

Keyword(s):

Material Properties ◽

Failure Modes ◽

Mechanical Anisotropy ◽

Failure Behavior ◽

Fused Filament Fabrication ◽

Content Type ◽

Orthotropic Composite ◽

Material Extrusion ◽

Specific Material ◽

Strength And Stiffness

Purpose Mechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on investigating the effects of design choices offered by material extrusion AM – namely, the choice of infill pattern – on the structural performance and optimality of a given optimized topology. Elucidation of these effects provides evidence that using design tools that incorporate anisotropic behavior is necessary for designing truly optimal structures for manufacturing via AM. Design/methodology/approach A benchmark topology optimization (TO) problem was solved for compliance minimization of a thick beam in three-point bending and the resulting geometry was printed using fused filament fabrication. The optimized geometry was printed using a variety of infill patterns and the strength, stiffness and failure behavior were analyzed and compared. The bending tests were accompanied by corresponding elastic finite element analyzes (FEA) in ABAQUS. The FEA used the material properties obtained during tensile and shear testing to define orthotropic composite plies and simulate individual printed layers in the physical specimens. Findings Experiments showed that stiffness varied by as much as 22% and failure load varied by as much as 426% between structures printed with different infill patterns. The observed failure modes were also highly dependent on infill patterns with failure propagating along with printed interfaces for all infill patterns that were consistent between layers. Elastic FEA using orthotropic composite plies was found to accurately predict the stiffness of printed structures, but a simple maximum stress failure criterion was not sufficient to predict strength. Despite this, FE stress contours proved beneficial in identifying the locations of failure in printed structures. Originality/value This study quantifies the effects of infill patterns in printed structures using a classic TO geometry. The results presented to establish a benchmark that can be used to guide the development of emerging manufacturing-oriented TO protocols that incorporate directionally-dependent, process-specific material properties.

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The interactive effect of insight and cuteness in driving purchase likelihood: a lay belief of creativity

Asia Pacific Journal of Marketing and Logistics ◽

10.1108/apjml-04-2021-0274 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Felix Septianto ◽

Rokhima Rostiani ◽

Widya Paramita

Keyword(s):

New Products ◽

Interactive Effect ◽

Experimental Studies ◽

New Product ◽

Underlying Mechanism ◽

Content Type ◽

Narrative Study ◽

Managerial Implications ◽

Purchase Likelihood

PurposeWhile new product introductions can potentially promote growth and benefit for brands, it remains unclear how marketers can develop effective communication strategies to increase the chance of success for new products. The present research investigates the role of cuteness in leveraging the effectiveness of a narrative emphasizing an insight versus an effort in this regard.Design/methodology/approachThis research presents two experimental studies. Study 1 examines the moderating role of cuteness on the likelihood of purchasing a new product featuring an insight-based (vs effort-based) narrative. Study 2 extends the findings of Study 1 using different stimuli and establishes the underlying mechanism.FindingsResults show that when a cuteness appeal is present, an insight-based (vs effort-based) narrative will lead to a higher purchase likelihood. However, these differences do not emerge when a cuteness appeal is absent (a control condition). Further, perceived brand creativeness will mediate this effect.Originality/valueThe findings of this research contribute to the literature on lay belief of creativity, cuteness, and product narrative, as well as managerial implications on how to promote new products.

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Perinatal Hypercholesterolemia Exacerbates Atherosclerosis Lesions in Offspring by Altering Metabolism of Trimethylamine-N-Oxide and Bile Acids

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvbaha.117.309923 ◽

2017 ◽

Vol 37 (11) ◽

pp. 2053-2063 ◽

Cited By ~ 21

Author(s):

Charlotte Trenteseaux ◽

Anh-thu Gaston ◽

Audrey Aguesse ◽

Guillaume Poupeau ◽

Pierre de Coppet ◽

...

Keyword(s):

Gene Expression ◽

Apolipoprotein E ◽

Bile Acids ◽

Experimental Studies ◽

Underlying Mechanism ◽

Female Offspring ◽

Promoter Regions ◽

Maternal Hypercholesterolemia ◽

Atherosclerosis Development ◽

Deficient Mice

Objective— Experimental studies suggest that maternal hypercholesterolemia may be relevant for the early onset of cardiovascular disease in offspring. We investigated the effect of perinatal hypercholesterolemia on the atherosclerosis development in the offspring of apolipoprotein E–deficient mice and the underlying mechanism. Approach and Results— Atherosclerosis and related parameters were studied in adult male or female apolipoprotein E–deficient mice offspring from either normocholesterolemic or hypercholesterolemic mothers and normocholesterolemic fathers. Female born to hypercholesterolemic mothers had more aortic root lesions than female born to normocholesterolemic mothers. Lesions in whole aorta did not differ between groups. Higher trimethylamine-N-oxide levels and Fmo3 hepatic gene expression were higher in female born to hypercholesterolemic mothers offspring compared with female born to normocholesterolemic mothers and male. Trimethylamine-N-oxide levels were correlated with the size of atherosclerotic root lesions. Levels of hepatic cholesterol and gallbladder bile acid were greater in male born to hypercholesterolemic mothers compared with male born to normocholesterolemic mothers. At 18 weeks of age, female born to hypercholesterolemic mothers showed lower hepatic Scarb1 and Cyp7a1 but higher Nr1h4 gene expression compared with female born to normocholesterolemic mothers. Male born to hypercholesterolemic mothers showed an increase in Scarb1 and Ldlr gene expression compared with male born to normocholesterolemic mothers. At 25 weeks of age, female born to hypercholesterolemic mothers had lower Cyp7a1 gene expression compared with female born to normocholesterolemic mothers. DNA methylation of Fmo3, Scarb1 , and Ldlr promoter regions was slightly modified and may explain the mRNA expression modulation. Conclusions— Our findings suggest that maternal hypercholesterolemia may exacerbate the development of atherosclerosis in female offspring by affecting metabolism of trimethylamine-N-oxide and bile acids. These data could be explained by epigenetic alterations.

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Ship Roll Motion Damping Using Bilge Keels – A Detailed CFD Investigation

10.5957/wmtc-2015-066 ◽

2015 ◽

Author(s):

Joshua Counsil ◽

Kevin McTaggart ◽

Dominic Groulx ◽

Kiari Boulama

Keyword(s):

Experimental Studies ◽

The Body ◽

Navier Stokes ◽

Roll Motion ◽

Empirical Methods ◽

Viscous Effects ◽

Vortex Interactions ◽

Ship Roll ◽

Semi Empirical ◽

Bilge Keel

A study has been undertaken to test the value of unsteady Reynolds-averaged Navier-Stokes (URANS) and traditional semi-empirical methods in the face of complex ship roll phenomena, and provide insight into the selection of bilge keel span for varying roll amplitudes. The computational fluid dynamics (CFD) code STAR-CCM+ is employed and two-dimensional submerged bodies undergoing forced roll motion are analyzed. The spatial resolution and timestepping scheme are validated by comparison with published numerical and experimental studies. The model is then applied to a fully-submerged circular cylinder with bilge keels of varying span and undergoing roll motion at varying angular amplitudes. Extracted hydrodynamic coefficients indicate that in general, increasing displacement amplitude and bilge keel span yields increased added mass and increased damping. The relationship is complex and highly dependent upon vortex interactions with each other and the body. The semi-empirical methods used for comparison yield good predictions for simple vortex interactions but fail where viscous effects are strong. Hence, URANS methods are shown to be necessary for friction-dominated flows while semi-empirical methods remain useful for initial design considerations.

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Mixed emotional appeal enhances advertising effectiveness of pro-environmental luxury brands: the mediating role of cognitive flexibility

Asia Pacific Journal of Marketing and Logistics ◽

10.1108/apjml-10-2020-0719 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Kaushalya Nallaperuma ◽

Felix Septianto ◽

Argho Bandyopadhyay

Keyword(s):

Cognitive Flexibility ◽

Experimental Studies ◽

Underlying Mechanism ◽

Advertising Effectiveness ◽

Luxury Brands ◽

Content Type ◽

Mixed Emotions ◽

Mediating Role ◽

Emotional Appeal ◽

Emotional Appeals

PurposeThe concepts of luxury and pro-environment may be viewed as being in contradiction with each other. Consequently, it is unclear how to promote pro-environmental luxury brands. The present research seeks to develop effective advertising strategies for pro-environmental luxury brands by employing mixed emotional appeals.Design/methodology/approachTwo experimental studies were conducted to test two hypotheses. Study 1 examines the effects of mixed emotions (happiness and sadness vs. happiness alone) on intentions to purchase a pro-environmental luxury product. Study 2 replicates the findings of Study 1 using a different product and extends it by establishing the underlying mechanism.FindingsThe results reveal that an advertisement featuring mixed emotions of happiness and sadness (vs. happiness alone) enhances intentions to purchase a pro-environmental luxury product. Further, the effect is mediated by cognitive flexibility.Originality/valueThe present research tests a novel perspective on how mixed emotional appeals can leverage the advertising effectiveness of pro-environmental luxury brands.

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The matching effect of anthropomorphized brand roles and product messaging on product attitude

Asia Pacific Journal of Marketing and Logistics ◽

10.1108/apjml-12-2019-0725 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Yuanqiong He ◽

Qi Zhou ◽

Shuojia Guo ◽

Jie Xiong

Keyword(s):

Boundary Conditions ◽

Experimental Studies ◽

Underlying Mechanism ◽

Mediation Effect ◽

Processing Fluency ◽

Mechanism Study ◽

Matching Effect ◽

Content Type ◽

Construal Levels ◽

Peripheral Locus

PurposeThis study aims to investigate the construal congruence of anthropomorphized brand roles and product messaging and its underlying mechanism on consumers' product attitude.Design/methodology/approachFour experimental studies were conducted to test the hypotheses. Study 1 investigated the framing effect of anthropomorphized brand roles (servant vs partner) in consumers' minds. Study 2 examined the matching effect of anthropomorphized brand roles and product messaging on product attitude. 132 students were randomly assigned to a 2 (anthropomorphized roles: servant vs partner) × 2 (product messaging: higher-level construal vs lower-level construal) between-subject factorial design. Study 3 tested the mediation effect of processing fluency underlying the construal congruence mechanism. Study 4 replicated the results of study 3 and further examined the boundary conditions by introducing product innovation locus as a moderator. A total of 218 students were randomly assigned to a 2 (anthropomorphized role: servant vs partner) × 2 (product messaging: higher-level construal vs lower-level construal) × 2 (innovation locus: core innovation vs peripheral locus) between-subjects design experiment.FindingsThe results demonstrate that a construal match between product messaging and anthropomorphized brand roles –anthropomorphized “servant” with higher-level construal messaging and anthropomorphized “partner” with lower-level construal messaging – can positively influence consumers' attitude via enhanced processing fluency. Furthermore, this construal matching effect on product attitude is moderated by the innovation locus of the product.Practical implicationsThis study reveals that anthropomorphized brand roles with compatible product messaging in the associated construal levels lead to more favorable product attitudes. Furthermore, the matching effect of anthropomorphized brand roles and product messaging is stronger for products with peripheral innovation than with core innovation.Originality/valueOur study contributes to the literature in two ways. First, it provides new insights into the construal matching effect of anthropomorphized brand roles and product messaging. Second, it investigates the boundary conditions of the above-mentioned construal fit mechanism.

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