Target Shape Optimization of 3D Compliant Mechanism With Superelastic Joints and Shape Memory Actuation

2019 ◽  
Author(s):  
Jovana Jovanova ◽  
Angela Nastevska ◽  
Mary Frecker
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Nickel Titanium ◽  
Different Temperatures ◽  
Superelastic Behavior ◽  
Over Time

Abstract The shape memory effect and the superelasticity of nickel titanium (NiTi) alloys are beneficial for design of compliant mechanisms. The superelastic behavior of NiTi can be tailored for optimal flexure design in the compliant mechanism, allowing large deformation and shape change. The shape memory effect can also be utilized to actuate the compliant mechanism flexures enabling programing of the material to take on variety of shapes at different temperatures over time. The compliant mechanism analyzed in this work is inspired from 3D multi leg spider-like locomotion, enabling movement in all directions by triggering different target shapes in time. The control of the material spatial distribution facilitated by additive manufacturing will enable tailored superelastic and shape memory behavior in the flexures of the multifunctional 3D compliant mechanism. Design optimization and analyses as well as overall shape change are explored in this work. Superelastic joints are introduced as flexures to enable segment flexibility. The temperature change is used for actuation taking in consideration different initial strain conditions.

Thermoelastic Martensitic Transformations and the Nature of the Shape Memory Effect

1983 ◽  
Vol 21 ◽  
Author(s):  
C. M. Wayman
Keyword(s):  
Single Crystal ◽  
Shape Memory ◽  
Crystal Structures ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Change ◽  
Parent Phase ◽  
Shape Deformation ◽  
Initial Shape ◽  
Plate Group

ABSTRACTInvestigations of the shape memory effect in alloys forming thermoelastic martensites with various crystal structures (2H, 3R, 9R and 18R) reveal that universal behavior exists. A unified explanation of the martensite deformation processes and subsequent shape recovery is now in hand, even though the various martensites are both internally twinned and internally faulted and, in addition, have different crystal structures. In cases studied to date, an initial parent phase single crystal transforms into self-accommodating arrangements of martensite variants (plates) which are characterized by “plate groups.” Each group consists of four variants. The average shape deformation in a plate group is essentially zero.Upon stressing below the Mf temperature the martensite undergoes deformation by detwinning (2H and 3R only), variant-variant coalescence and twinning processes, and further group-to-group coalescence. The deformed specimen eventually becomes a single crystal of martensite consisting of that particular habit plane variant whose shape deformation permits maximum extension in the direction of the applied stress. The deformed martensite persists after unloading has occurred; reverse rearrangements of twins and variants do not occur. Specimens deformed below Mf regain their initial shape characteristic of the initial parent phase upon heating from As to Af, during which the single crystal of martensite obtained by stressing the 24-variant configuration transforms back to the original parent phase single crystal in a unique manner, which is basically a simple “unshearing” process. The unshearing is the essence of the memory.The two-way shape memory effect results after the initial martensitic transformation upon cooling is preprogrammed by the introduction of stresses which preferentially bias the transformation so that only a single variant of martensite forms upon cooling. The shape change of this single variant causes the characteristic spontaneous “bending” upon cooling. The characteristic “unbending upon heating is as with the conventional “one-way” shape memory effect.

Orthopaedic Aspects and Peculiarities of Operative Treatment for Funnel Breast in Children and Adolescents

2011 ◽  
Vol 18 (3) ◽  
pp. 3-9
Author(s):  
Oleg Alekseevich Malakhov ◽  
K V Zherdev ◽  
O B Chelpachenko ◽  
O A Malakhov ◽  
K V Zherdev ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Operative Treatment ◽  
Age Groups ◽  
Nickel Titanium ◽  
Spine Deformity ◽  
Funnel Chest ◽  
Cosmetic Effect ◽  
Full Correction

Results of operative treatment using radical thoracoplasty in 31 patients with funnel breast were analyzed. Mean age of patients was 14.98±4.36 years. All patients had concomitant spine deformity. For purpose of cosmetic effect improvement the mini-invasive submammary accesses were used. Fixatives of sternocostal complex from nickel-titanium with shape-memory were worked out. The shape memory effect was achieved by cooling of the implant that resulted in implant plasticity. After being inserted the implant restored its original shape. That technique allowed achieving full correction of the deformity and positive cosmetic effect in all patients. No complications associated with plate migration were revealed. Radical thoracoplasty with thoracocostal complex stabilization by plate with shape-memory effect is pathogenetically justified and allows correcting the funnel chest of any degree and form and is indicated to patients of any age groups.

scholarly journals Two-Way Shape Memory Effect Induced by Tensile Deformation in Columnar-Grained Cu71.7Al18.1Mn10.2 Alloy

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2109 ◽  
Author(s):  
Pei-Sheng Yao ◽  
Hai-You Huang ◽  
Yan-Jing Su ◽  
Jian-Xin Xie
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Tensile Deformation ◽  
Shape Change ◽  
Uniaxial Tensile ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Deformation Strain ◽  
The Relationship

Columnar-grained Cu71.7Al18.1Mn10.2 shape memory alloy (SMA) was prepared by a directional solidification method and exhibited a high superelasticity of 8.18% and excellent ductility at room temperature, which provided the possibility of obtaining high shape memory. However, proper pre-deformation is an essential part of repeatedly obtaining large and stable shape change. In this paper, one-time uniaxial tensile pre-deformation was carried out at the temperature range −70–−80 °C. Then, the two-way shape memory effect (TWSME) of the alloy was evaluated by the martensitic transformation strain (εM) which was measured by a thermal expansion test to investigate the relationship between the pre-deformation strain (εT) and the TWSME. The results showed that εM of the columnar-grained Cu71.7Al18.1Mn10.2 alloy increased at first and then decreased with the increase of εT. The maximum value 2.91% of the εM could be reached when εT was 6%. The effects of the εT on transformation temperatures were also measured by differential scanning calorimetry. Based on the variations of transformation temperatures, the relationship between the internal stress induced by the pre-deformation process and the εM, and the influence mechanism of the pre-deformation strain on the TWSME in columnar-grained Cu71.7Al18.1Mn10.2 alloy, were discussed. The results obtained from this work may provide reference for potential applications of Cu-based SMAs, such as self-control components, fasteners, etc.

Behavior of the nickel-titanium alloys with the shape memory effect under conditions of shock wave loading

2011 ◽  
Vol 53 (4) ◽  
pp. 824-829 ◽  
Author(s):  
S. V. Razorenov ◽  
G. V. Garkushin ◽  
G. I. Kanel’ ◽  
O. A. Kashin ◽  
I. V. Ratochka
Keyword(s):  
Shock Wave ◽  
Shape Memory ◽  
Titanium Alloys ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Nickel Titanium ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Nickel Titanium Alloys

Hysteretic Behavior of Concrete Cylinders Confined by Active Confining SMA Wire Jackets

2010 ◽  
Vol 654-656 ◽  
pp. 2099-2102
Author(s):  
Eun Soo Choi ◽  
Hack Soo Lee ◽  
Joo Nam Park ◽  
Bak Soon Cho
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Hysteretic Behavior ◽  
Confined Concrete ◽  
Concrete Cylinders ◽  
Superelastic Behavior ◽  
Active Confinement ◽  
Compressive Tests

Shape memory alloy (SMA) wire jackets are distinct from conventional jackets for concrete members since they can provide active confinement easily. The applications of SMAs in civil engineering are on the increase since SMAs show unique properties of shape memory effect and superelastic behavior. Especially, the seismic application of SMAs for confining concrete becomes a hot issues in recent. Thus, this study conducts cyclic compressive tests of concrete cylinders jacketed by shape memory alloy (SMA) wires which can provide active confinement due to shape memory effect. Monotonic compressive tests provide only the peak strength and the ultimate strain for confined concrete. However, confined concrete is exposed to the repeating of loading and unloading during an earthquake. Also, this study performs the same tests for concrete cylinders jacketed by steel jackets which provide only passive confinement and the results are compared to those of SMA wire jackets. This study provides the basic information of concrete behavior confined by active or passive external jackets.

scholarly journals Shape memory effect in nanoindentation of nickel–titanium thin films

2003 ◽  
Vol 83 (2) ◽  
pp. 257-259 ◽  
Author(s):  
G. A. Shaw ◽  
D. S. Stone ◽  
A. D. Johnson ◽  
A. B. Ellis ◽  
W. C. Crone
Keyword(s):  
Thin Films ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Nickel Titanium ◽  
Titanium Thin Films
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