On the design of porous structures with enhanced fatigue life

Javid, Farhad; Liu, Jia; Rafsanjani, Ahmad; Schaenzer, Megan; Pham, Minh Quan; Bäckman, David; Yandt, Scott; Innes, Matthew; Booth-Morrison, Christopher; Gerendás, Miklós; Scarinci, Thomas; Shanian, Ali; Bertoldi, Katia

doi:10.1016/j.eml.2017.08.002

Cited by 31 publications

(20 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a concept that merits further study to advance understanding of the effect of such tailored microstructures. In steels-materials that deform by plasticity-change in pore shape from a circle to an ''S'' shape increased the fatigue life due to reduction of local stresses [25]. In SMAs, however, the promotion of local transformation to relieve stresses as demonstrated in this section may also lead to local transformation-induced slip, leading to an accumulation of defect content over many cycles, which can lead to functional fatigue.…”

Section: Simulation: Local Orientations Can Be Tailored To Relieve Stmentioning

confidence: 81%

Influence of Structure and Microstructure on Deformation Localization and Crack Growth in NiTi Shape Memory Alloys

Paul

Fortman

Paranjape

et al. 2018

Shap. Mem. Superelasticity

View full text Add to dashboard Cite

Porous NiTi shape memory alloys have applications in the biomedical and aerospace fields. Recent developments in metal additive manufacturing have made fabrication of near-net-shape porous products with complicated geometries feasible. There have also been developments in tailoring site-specific microstructures in metals using additive manufacturing. Inspired by these developments, we explore two related mechanistic phenomena in a simplified representation of porous shape memory alloys. First, we computationally elucidate the connection between pore geometry, stress concentration around pores, grain orientation, and strain-band formation during tensile loading of NiTi. Using this, we present a method to engineer local crystal orientations to mitigate the stress concentrations around the pores. Second, we experimentally document the growth of cracks around pores in a cyclically loaded superelastic NiTi specimen. In the areas of stress concentration around holes, cracks are seen to grow in large grains with [1 1 0] oriented along the tensile axis. This combined work shows the potential of local microstructural engineering in reducing stress concentration and increasing resistance to propagation of cracks in porous SMAs, potentially increasing the fatigue life of porous SMA components.

show abstract

Section: Simulation: Local Orientations Can Be Tailored To Relieve Stmentioning

confidence: 81%

Influence of Structure and Microstructure on Deformation Localization and Crack Growth in NiTi Shape Memory Alloys

Paul

Fortman

Paranjape

et al. 2018

Shap. Mem. Superelasticity

View full text Add to dashboard Cite

show abstract

“…Low porosity applications, i.e. below 5%, however, also exist, and are often employed in extreme environments subjected to severe service conditions [40–45]. Recent work on low-porosity metamaterials has shown the achievement of high tunability in both Poisson’s ratio and band gaps through the use of staggered elliptical voids in orthogonal tessellations of ultralow porosity (less than 2%) [41,45].…”

Section: Introductionmentioning

confidence: 99%

“…Recent work on low-porosity metamaterials has shown the achievement of high tunability in both Poisson’s ratio and band gaps through the use of staggered elliptical voids in orthogonal tessellations of ultralow porosity (less than 2%) [41,45]. Other works focused on non-elliptical slots with ‘S’ shape, and reported enhanced fatigue life [40], more broadband absorption for high-frequency acoustic noise [42], and improved cooling effectiveness than traditional circular voids [44]. Shifted and rotated straight slots in orthogonal tessellations have been also used in auxetic metamaterials with low-frequency band gaps [46,47].…”

Section: Introductionmentioning

confidence: 99%

Generalized tessellations of superellipitcal voids in low porosity architected materials for stress mitigation

Leng

Schaenzer

et al. 2021

Proc. R. Soc. A.

Self Cite

View full text Add to dashboard Cite

Stress concentration is a crucial source of mechanical failure in structural elements, especially those embedding voids. This paper examines periodic porous materials with porosity lower than 5%. We investigate their stress distribution under planar multiaxial loading, and presents a family of geometrically optimized void shapes for stress mitigation. We adopt a generalized description for both void geometry and planar tessellation patterns that can handle single and multiple voids of arbitrary void shape at a generic angle. The role of void shape evolution from diamond to rectellipse on the stress-distribution is captured at the edge of voids in a representative volume element (RVE) made of non-equal length periodic vectors. Theoretical derivations, numerical simulations along with experimental validation of the strain field in thermoplastic polymer samples fabricated by laser cutting unveil the role of geometric parameters, e.g. superellipse order, aspect ratio and rotation angle, that minimize stress peak and ameliorate stress distribution around voids. This work extends and complements classical theory by providing fundamental insights into the role that tessellation, void shape and inclination play in the stress distribution of low-porosity architected materials, thus introducing essential guidelines of broad application for stress-minimization and failure mitigation in diverse sectors.

show abstract

“…Some of the most popular geometries are: chiral and antichiral [ 7 , 8 , 9 ], re-entrant [ 10 , 11 ], double arrowhead [ 12 , 13 ] and rotating polygons [ 14 ]. Auxetic behavior could be also the result of precisely designed cuts, which have been shown by Francesconi et al [ 15 ] and Javid et al [ 16 ] All these geometries are usually used to build cellular structure of materials. Studies of these structures have been performed both experimentally and theoretically, using numerical methods, e.g., a review of the manufacture, mechanical properties of auxetic foams was published by Critchley et al [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Thermoauxetic Behavior of Composite Structures

Jopek

Stręk

2018

Materials

View full text Add to dashboard Cite

This paper presents a study of new two-dimensional composite structures with respect to their thermomechanical properties. The investigated structures are based on very well-known auxetic geometries—i.e., the anti-tetrachiral and re-entrant honeycomb—modified by additional linking elements, material which is highly sensitive to changes of temperature. The study shows that temperature can be used as a control parameter to tune the value of the effective Poisson’s ratio, which allows, in turn, changing its value from positive to negative, according to the temperature applied. The study shows that such thermoauxetic behavior applies both to composites with voids and those completely filled with material.

show abstract

On the design of porous structures with enhanced fatigue life

Cited by 31 publications

References 17 publications

Influence of Structure and Microstructure on Deformation Localization and Crack Growth in NiTi Shape Memory Alloys

Influence of Structure and Microstructure on Deformation Localization and Crack Growth in NiTi Shape Memory Alloys

Generalized tessellations of superellipitcal voids in low porosity architected materials for stress mitigation

Thermoauxetic Behavior of Composite Structures

Contact Info

Product

Resources

About