Frequency Control of Light-Activated Shape Memory Polymer Laminated Beams: Characterization and Experiments

2016 ◽  
Author(s):  
Huiyu Li ◽  
Xufang Zhang ◽  
Hornsen Tzou
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Young's Modulus ◽  
Frequency Control ◽  
Reverse Reaction ◽  
Flexible Beam

Light-activated shape memory polymers (LaSMPs) exhibit stiffness variations when exposed to ultraviolet (UV) lights. Thus, LaSMP could manipulate structural natural frequencies with UV light exposures when laminated on structures. This study aims to experimentally demonstrate the effectiveness of LaSMP frequency control of a flexible beam. The natural frequency of a three-layered Euler-Bernoulli beam composed of LaSMP, adhesive tape and the flexible beam is analyzed and its frequency formulation exhibits the LaSMP stiffness influence. As the LaSMP adopted in this study is a new spiropyran based composition, a generic Young’s modulus model is proposed and then simplified to model the present LaSMP composition. To make sure the experiment is carried out in a homogenous light field, the light intensities of the UV surface light source at different positions are tested. The temperature change of the LaSMP sample under UV exposures is also measured. The time constant of the reverse reaction and the threshold intensity of the reverse reaction are measured. LaSMP Young’s modulus variation is tested with a uniaxial tension experiment. The constitutive model of LaSMP’s Young’s modulus is validated by experimental data. With these preparations, the LaSMP laminated flexible beam model is exposed to the UV lights and its natural frequencies are identified with a data acquisition and analysis system. The maximum natural frequency variation ratio achieves 5.67%. Comparing both theoretical and experimental data of natural frequency control, this study also validates the LaSMP Young’s modulus constitutive model.

scholarly journals Effect of Nanopores on Mechanical Properties of the Shape Memory Alloy

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 529
Author(s):  
Chunzhi Du ◽  
Zhifan Li ◽  
Bingfei Liu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Residual Strain ◽  
Surface Effect ◽  
Young's Modulus ◽  
Strain Curve ◽  
Stress Strain ◽  
Strength Limit

Nanoporous Shape Memory Alloys (SMA) are widely used in aerospace, military industry, medical and health and other fields. More and more attention has been paid to its mechanical properties. In particular, when the size of the pores is reduced to the nanometer level, the effect of the surface effect of the nanoporous material on the mechanical properties of the SMA will increase sharply, and the residual strain of the SMA material will change with the nanoporosity. In this work, the expression of Young’s modulus of nanopore SMA considering surface effects is first derived, which is a function of nanoporosity and nanopore size. Based on the obtained Young’s modulus, a constitutive model of nanoporous SMA considering residual strain is established. Then, the stress–strain curve of dense SMA based on the new constitutive model is drawn by numerical method. The results are in good agreement with the simulation results in the published literature. Finally, the stress-strain curves of SMA with different nanoporosities are drawn, and it is concluded that the Young’s modulus and strength limit decrease with the increase of nanoporosity.

scholarly journals Pengukuran Modulus Young dengan Analisis Keadaan Resonansi Batang Aluminium yang Bergetar Menggunakan ImageMeter

2017 ◽  
Vol 2 ◽  
pp. 346
Author(s):  
Maria Tefa ◽  
Ign Edi Santosa
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Young’S Modulus ◽  
Natural Frequency ◽  
Measurement Method ◽  
Young's Modulus ◽  
Resonance Condition ◽  
Alternating Current ◽  
Resonance Frequencies ◽  
The Magnetic Field

<p class="AbstractEnglish"><strong>Abstract:</strong> An experiment to determine Young’s Modulus by analyzing the vibrations of an aluminum bar has been conducted. The aluminium bar is vibrated by the magnetic field. A tiny magnet is glued at the free end of the bar. A coil carrying an alternating current generates an alternating magnetic field. The resonance condition is investigated by the measurement of its wavelength using the ImageMeter application. The natural frequency of the aluminum bar is determined from the measurement of its resonance frequencies. The natural frequency and the bar length are used to calculate Young’s Modulus. The experimental data shows the Young’s Modulus of aluminum is . This measurement method is used for learning purposes.</p><p class="KeywordsEngish"> </p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Telah dilakukan pengukuran nilai Modulus Young dengan analisis getaran dari sebuah batang aluminium. Batang aluminium digetarkan dengan medan magnet. Magnet kecil ditempelkan pada bagian ujung batang aluminium yang bebas. Sebuah kumparan yang berada di bawah ujung batang aluminium  diberi arus bolak balik yang dapat diatur frekuensinya. Pada frekuensi tertentu akan terjadi resonansi dengan mengikuti pola yang khas. Keadaan resonansi batang aluminium ini dibuktikan dari hasil pengukuran panjang λ menggunakan aplikasi <em>ImageMeter</em>. Selanjutnya frekuensi alami batang aluminium ditentukan dari pengukuran frekuensi resonansinya. Nilai Modulus Young aluminium dihitung dari nilai frekuensi alami dan panjang batang. Dari hasil pengukuran diperoleh nilai Modulus Young . Metoda pengukuran ini digunakan untuk keperluan pembelajaran.</p><p class="KataKunci"><strong></strong><em><br /></em></p>

Three Dimensional Finite Element Analysis of Transverse Free Vibration of Self-Pierce Riveting Beam

2007 ◽  
Vol 344 ◽  
pp. 647-654 ◽  
Author(s):  
Xiao Cong He ◽  
Ian Pearson ◽  
Ken W. Young
Keyword(s):  
Finite Element ◽  
Young’S Modulus ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Self-pierce riveting (SPR) is nowadays widely used in the car manufacturing industry where aluminium alloys are used for body construction. For the design of mechanical structures, formed by the joining of component parts, a knowledge of the vibration characteristics of different joint types (adhesive bonding, spot welding, SPR etc) is essential. The free transverse vibration characteristics of single lap-jointed encastre SPR beams are investigated theoretically in this paper using the three dimensional finite element method (FEM). Numerical examples are provided to show the influence on the natural frequencies, natural frequency ratios and mode shapes of these beams caused by variations in the material properties (E and υ) of the sheet material. It is shown that the transverse natural frequencies of single lap jointed encastre SPR beams increases significantly as the Young’s Modulus of the sheets increases, but only slight changes are encountered for variations of Poisson’s Ratio. It is found that an exponential curve gives an acceptable fit to the relationship between natural frequency and Young’s Modulus. As expected, odd modes shapes were found to be symmetrical about the mid-length position and even modes were anti-symmetrical.

Design of Shape Memory Alloy Springs With Applications in Vibration Control

1993 ◽  
Vol 115 (1) ◽  
pp. 129-135 ◽  
Author(s):  
C. Liang ◽  
C. A. Rogers
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vibration Control ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Design Method ◽  
Control Area ◽  
Spring Constant ◽  
Damping Capacity

Shape memory alloys (SMAs) have several unique characteristics, including their Young’s modulus-temperature relations, shape memory effects, and damping characteristics. The Young’s modulus of the high-temperature austenite of SMAs is about three to four times as large as that of low-temperature martensite. Therefore, a spring made of shape memory alloy can change its spring constant by a factor of three to four. Since a shape memory alloy spring can vary its spring constant, provide recovery stress (shape memory effect), or be designed with a high damping capacity, it may be useful in adaptive vibration control. Some vibration control concepts utilizing the unique characteristics of SMAs will be presented in this paper. Shape memory alloy springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some design approaches based upon linear theory have been proposed for shape memory alloy springs. A more accurate design method for SMA springs based on a new nonlinear thermomechanical constitutive relation of SMA is also presented in this paper.

Frequency manipulation of a light-activated shape-memory polymer-laminated cylindrical shell

2021 ◽  
pp. 095440892110632
Author(s):  
Tao He ◽  
Pengpeng Zhu ◽  
Xiangmin Zhang
Keyword(s):  
Cylindrical Shell ◽  
Shape Memory ◽  
Natural Frequency ◽  
Frequency Control ◽  
Shape Memory Polymer ◽  
Control Effect ◽  
Optimal Scheme ◽  
Simply Supported ◽  
Control Capability ◽  
Laminated Cylindrical Shell

A light-activated shape-memory polymer is a novel smart material that exhibits a dynamic Young's modulus when exposed to light. The non-contact actuation feature facilitates the lamination of a light-activated shape-memory polymer on host structures for realising frequency control. In this study, we investigated the natural frequency of a simply supported cylindrical shell coupled with light-activated shape-memory polymer patches located arbitrarily on the shell. Initially, we compared the natural frequency of a completely laminated cylindrical shell using two different approaches. Further, we analysed the effect of changes in the length and location of the light-activated shape-memory polymer patch pair on the natural frequency of the cylindrical shell. Based on the experimental results, we propose an optimal scheme, wherein several light-activated shape-memory polymer patch pairs are distributed on the surface of the shell, and the frequency control capability of the proposed scheme is evaluated comprehensively. The results verify that the optimal scheme has an adequate control effect on the natural frequency of the cylindrical shell.

Multiscale Modeling of Light Activated Shape Memory Polymer

2008 ◽  
Author(s):  
Richard Beblo ◽  
Lisa Mauck Weiland
Keyword(s):  
Shape Memory ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Shape Memory Polymer ◽  
Scale Model ◽  
Cross Link ◽  
Material Response ◽  
Rotational Isomeric State ◽  
Stress Strain Relation ◽  
Cross Links

Presented is the development of a multi-scale model predicting the material response of a light activated shape memory polymer. Rotational Isomeric State (RIS) theory is used to build a molecular scale model of the polymer chain backbone, tracking the distances between cross-links. Cross-link to cross-link distances are then used with Boltzmann statistical mechanics to predict material response, generating Young’s modulus and stress-strain relation predictions. Young’s modulus is predicted by the model to be 0.049 and 3.2 MPa for the soft and hard states of the polymer respectively. Experimentally determined properties are also presented with reported moduli of 2.0 and 11.4 MPa in the soft and hard states respectively.

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