笔者想承认DFG优先方案的支持，1599年"中铁性材料的热量作用:用于冷却新概念"（项目:EG101 / 23-1，SCHU2217 / 2-1，SE704 / 2-1，EG101 / 29 -2，SCH2217 / 3-2，SE704 / 2-2）。

1.样品制备<ol><li>测量在SMA丝带与卡钳和确定样品的横截面。 </li><li>通过用高发射率（ε= 0.96）的涂料薄层涂布色带准备IR测量样品。 注意:该涂料被分类为刺激物。手套，安全眼镜和嘴保护必须油漆的处理期间被磨损。 </li></ol> 2.材质稳定（训练） 注:初始机械循环导致了机械和热的材料稳定化。的稳定化效果的调查，以及训练过程本身，需要使用致动器的并装在试验台的上水平以及红外照相机的传感器。 <ol><li>启动马达控制器程序并检查加载的设置。将设置更改为位置模式和命令模式。验证电机处于活动模式。 </li><li>小号ET的电机控制器程序的目标位置为0微米，然后点击"运行使能"按钮 - 在这个位置夹具之间的距离为90毫米。 </li><li>放置实验装置的夹具之间的样品，并使用一个特殊设计的对准工具对齐样品。 </li><li>使用顺序安装援助，以避免对称重传感器和样品弯曲载荷拧紧夹子。使用扭矩扳手紧固的螺钉，以确保可重现夹紧力（扭矩:20牛顿米）。 </li><li>检查当前的电机位置，并确保电机处于起始位置（0微米）。 </li><li>启动IR照相机软件并装载校准对于50毫米镜头用特写镜头相结合。选择的1280×100像素的图像尺寸和-20℃至50℃的温度范围。照相机通过使用马达聚焦部及定位确认整个样本是在视摄像机的领域。 注:红外摄像机，在combina灰与所选透镜系统中，具有焦距为50mm，F / 2，并在200毫米的工作距离为60微米的最小像素大小的孔（F）。 </li><li>打开该控制程序用于培训和材料特性，并设置控制参数（位移，速度，保持时间，最大和最小力，循环数和相机帧速率）。 <ol><li>设置开始位置（0微米），并选择在目标位置（4,500微米），使得材料经历一个完整的相变。 </li><li>设置线性直接驱动速度（速度装载/卸载），以满足所需的应变速率。选择5×10 -4秒-1（45微米/秒的致动器速度）的冷却过程有关的训练的应变速率。 <ol><li> （五）的基础上选择的应变速率确定线性直接驱动速度（ <img alt="EPSILON" src="/files/ftp_upload/53626/epsilon.jpg" /> ）和90毫米（诉初始样品长度（L 0）= &lt;IMG ALT ="小量"SRC ="/文件/ ftp_upload / 53626 / epsilon.jpg"/&gt;∙L 0） </li></ol></li><li>设置的保持时间为0秒。 </li><li>设定周期数为1与新的样品的第一个周期。 </li><li>设置样品特定的最小和最大的力的水平，以避免压缩载荷和拉伸过载（最小负载1MPa时，最大负载800兆帕）。 </li><li>选择50毫秒/帧的IR照相机采集速率（每秒20帧）。 </li><li>点击开始按钮加载设置。 </li></ol></li><li>打开红外摄像机的软件，选择文件名并分配5000帧。 <ol><li>从内部切换到外部触发源，并开始数据采集模式。 </li></ol></li><li>打开控制程序，并按下启动按钮实验。 </li><li>数据可视化<ol><li>一旦试验完成后，将数据加载到数据处理软件，并在力/位移，ST而言它形象化RESS /应变，力/时间和位置/时间图。 </li><li>加载IR数据进入IR照相机软件和评估时间分辨温度曲线。限定覆盖SMA色带的表面上的测量区和绘制样品相对于时间的平均最高和最低温度。 </li></ol></li><li>重复步骤2.6至2.9，直到材料显示稳定的机械性能和适应的开始位置，以补偿残余应变。 <ol><li>在前10个周期后，增加每个实验的周期数为10，与实验进行直到达到稳定的材料的行为。 </li></ol></li></ol> 3.材料表征注意:材料特性鉴定需要使用致动器的并装在试验台的上水平以及红外照相机的传感器。在表征过程的样品被加载并在执行以不同的速率卸载装卸后持有期。 <ol><li>如果在SMA色带已被松开和测试装备的控制系统中的训练后已关闭，重复步骤2.1至2.6，并再次夹住样品。如果不是这种情况下，操作流程如下: </li><li>打开控制程序的培训和材料特性，并设置控制参数（位移，速度，保温时间和摄像头帧周期数率）。 <ol><li>设置开始位置，以使所述样品是零负载下和设置目标位置等同于训练（4,500微米）的目标位置。 </li><li>设置线性直接驱动速度（速度装载/卸载），以满足所需的应变速率。选1×10 -1秒-1这导致绝热相变与为0.75mm×1.4毫米或更大的横截面样本（9000微米/秒的致动器速度）的应变速率。 </li><li>设定保温时间为180 SEC，这是足以使样品达到初始温度水平。 注意:保持时间具有由计算的热平衡时间常数（τ）和一个保持时间小于4×τ具有下一个表征实验开始前将增加实验后进行验证。 </li><li>设定周期数为1。 </li><li>设置样品特定的最小和最大的力的水平，以避免压缩载荷和拉伸过载（最小负载1MPa时，最大负载800兆帕）。 </li><li>选5毫秒/帧的IR照相机采集速率（每秒200帧）。 </li><li>点击开始按钮加载设置。 </li></ol></li><li>打开红外摄像机的软件，选择文件名并分配80000帧。 <ol><li>从内部切换到外部触发源，并开始数据采集模式。 </li></ol></li><li>打开控制程序，并按下启动按钮实验。 </li><li>加载IR数据进红外摄像机的软件。情节平均最高和最低样品温度与时间。导出的数据并计算热平衡的时间与数据处理软件10,11恒定。 </li><li>适应的保持时间，如果需要，基于所计算出的热平衡时间常数。 </li><li>重复步骤3.2至3.5，并改变从5×10 -5秒-1至1×10 -1秒-1的变形速度，以及从2％应变为5％的最大应变（最大应变相当于在训练期间的最大应变）。 </li><li>局部温度峰值的调查: 注意:该材料示出的elastocaloric作用的速率依赖性定位效果。这些效应仔细研究需要在SMA的温度分布的高特的分辨率。为了这个目的，所述红外线摄像机的透镜具有对通过显微镜透镜代替。显微镜透镜具有3.0的孔，1X的倍率为15的像素大小微米在195毫米的工作距离。 <ol><li>开关灯了，从红外摄像机领域中删除所有热源和更换镜头。 </li><li>改变相机校准设置，温度范围为20℃至50℃，并在500×250像素的图像尺寸内加载的显微镜透镜校准。使用电机聚焦部聚焦样品。 </li><li>在1×10 -1秒-1（9,000微米/秒）的应变速率进行拉伸试验，按照第2节所述的步骤:材质稳定。 </li></ol></li><li>数据可视化<ol><li>装载机械数据到数据处理软件并在力/位移，应力/应变，力/时间和位置/时间图而言​​可视它。 </li><li>加载IR数据进入IR照相机软件和评估时间分辨温度曲线。限定覆盖SMA色带的表面上的测量区和绘制平均值最大imum和样品相对于时间的最低温度。 </li></ol></li></ol> 4. Elastocaloric冷工艺注意:elastocaloric冷却过程的调查，需要在设置的上部和下部水平以及红外照相机的使用致动器和传感器。这些实验包括，以优化其工艺性能的控制参数的变化。 <ol><li>如果在SMA色带已被松开并且材料特性鉴定后测试装备已被关闭，重复步骤2.1至2.5，并再次夹住样品。如果不是这种情况下，操作流程如下: </li><li>启动红外摄像机软件和加载在50毫米镜头与特写镜头校准。选择的1280×1024像素的图像尺寸和-20℃至50℃的温度范围。照相机通过使用马达聚焦部及定位确保整个样品是在视摄像机的领域。 注:IR照相机在与所选择的透镜系统组合具有焦距50毫米，F / 2，并在200毫米的工作距离为60微米的最小像素大小的孔（F）。 </li><li>打开elastocaloric冷却过程中的控制程序和设定控制参数的线性直接驱动一（上层），线性直接驱动一和二，接触时间，最大值和最小值力，接触阶段，周期数和相机的速度（位移帧速率）。 <ol><li>设置的SMA装卸线性直接驱动的开始位置，从而使所述样品是零负载下和设置目标位置等同于训练（4,500微米）的目标位置。 </li><li>设置用于装载和在SMA卸线性直接驱动的速度（速度装载/卸载），以满足1×10 -1秒-1（9,000微米/秒）的应变速率。设置线性直接驱动的速度在设定至100的下水平毫米/秒。 </li><li>设置的接触时间为6秒。 注意:接触时间决定传热的持续时间和可设置为大于10毫秒的任何值。 </li><li>选择后装载/卸载方式的接触。 注:接触阶段影响装卸是绝热（装货/卸货后接触）或（装载/卸载过程中接触）热传递到散热器/源相结合。 </li><li>设定周期数到40。 </li><li>设置样品特定的最小和最大的力的水平，以避免压缩载荷和拉伸过载（最小负载1MPa时，最大负载800兆帕）。 </li><li>选择20毫秒/帧的IR照相机采集速率（每秒50帧）。点击开始按钮加载设置。 </li></ol></li><li>打开红外摄像机的软件，选择文件名并分配50000帧。从内部切换到外部触发源，并开始数据采集模式。 </li><li>打开控制程序控制我，然后按开始试验按钮。 </li><li>数据可视化<ol><li>一旦试验完成加载数据到数据处理软件和可视化以下数据:力/位移，应力/应变，温度/时间（散热片/源的温度），力/次，接触力/时间和位置线性执行器/时间。 </li><li>加载IR数据进入IR照相机软件和评估时间分辨温度曲线。限定覆盖在SMA样品表面以及散热器的表面与热源三个测量领域。导出的时间定义测量领域的解决平均值，最高和最低温度的数据，并将它们加载到数据处理软件。 </li><li>在温度/时间图可视化IR数据。 </li></ol></li><li>重复实验下的参数变化:应变，接触时间和接触阶段。 </li></ol> 5.模型验证<p类="jove_content"&gt;注意:热机械耦合材料模型的验证需要实验秉承材料稳定或材料特性。使用镍钛金属丝具有0.6毫米的横截面来执行实验研究。 <ol><li>以5×10 -5秒的应变速率-1和5％的应变进行的等温拉伸试验，通过执行在第2节中描述的步骤进行。 </li><li>一旦实验结束时，将数据加载到数据处理软件和可视化的应力/应变的测量。计算奥氏体的弹性模量和马氏体相，以变应变，以及滞后的宽度。上述数据功能为模型7机械输入数据。 </li><li>以1×10 -4秒-1，5×10 -4秒-1，1×10 -3秒-1，5×10 -3的应变率进行进一步的拉伸试验</s向上&gt;秒-1，1×10 -2秒-1，5×10 -2秒-1，1×10 -1秒-1来生成用于模型验证数据。 </li><li>如果完成了实验取样品从测试系统，并执行差示扫描量热测量（DSC）18，以确定热材料性质稳定的材料（相变和材料的比热容量的潜热）。 注:DSC测量提供了热机械耦合模型热量输入数据。 </li><li>启动步骤5.3中所述的拉伸试验的模拟。 <ol><li>实施形状记忆合金定制机型为商用有限元软件: <ol><li>选择几何节点，然后选择时间间隔来绘制1D线的几何形状。 </li><li>选择参数节点定义从STE机械试验鉴定模型参数p 5.2。 </li><li>右键单击定义节点，选择变量创建一个变量节点。选择变量节点，并确定从统计热力学19得到的转移概率定义算法。 </li><li>选择添加物理 ，并添加系数表PDE或一般形式的PDE来定义集描述超弹性形状记忆合金的行为的一维偏微分方程，由固定的动量平衡，内能和相变20的动力学方程的平衡。 </li></ol></li><li>选择初始值的子节点到电线的初始温度设定为环境温度。 <ol><li>选择狄利克雷边界条件来规定机械的边界条件用于施加以下第2节中所述的实验程序的菌株，在圣应变速率EP 5.3，约束线的一端的位移和处方的另一端的位移。 </li><li>选择狄氏边界条件设置，因为相比于细线大量夹具的热边界条件，恒定的温度。 注意:有限元软件的标准设置不导致会聚溶液。 </li><li> 求解配置的选择子节点修改标准设置（ 例如 ，绝对和相对容差和非线性的阻尼系数，迭代牛顿迭代求解器），然后点击"计算"来解算器运行。 </li></ol></li></ol></li><li>数据分析<ol><li>装载的实验和模拟的结果到数据分析软件和可视化的机械和热的数据。 </li><li>比较实验和仿真结果，相应的机械（应力/应变响应）和热（特别解决了温度的变化样品）材料的行为。 </li></ol></li></ol>

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The authors have nothing to disclose.

所提出的科学试验台能够通过执行该协议部分中描述的实验elastocaloric材料和冷却过程的全面调查。夹紧前的样品的精确对准是对于所有的实验是至关重要的。不良对准有可能导致早期材料失效。此外，最大施加应变对材料寿命显著影响，而所需的应变达到一个完整的相变取决于合金组合物。被调查NiTiCuV合金的转化菌株（参见图10）是显著比图9和图13中所示的...

基于铁性材料的固态冷却过程有潜力成为环境友好型替代传统的蒸汽压缩化进程。铁性材料可显示出磁，electrocaloric和elastocaloric效果1，2，以及这些影响，它们被描述为multicaloric材料行为3组合。中铁性材料的不同热量的影响目前正在调查作为德国科学基金会（DFG）优先计划SPP 1599的一部分"的铁性材料热量影响:对冷却新概念"4。形状记忆合金（SMA），这是该计划中调查，由于其较大的潜热5大展示效果elastocaloric，尤其是镍钛基合金。在高应变率下的应变诱发相变导致的SMA显著的温度变化，如在图1中所示。在从奥氏体绝热，放热相转变为马氏体增加SMA温度。从马氏体吸热转变为奥氏体导致一个显著温度下降。这些elastocaloric材料特性可用于固态通过施加合适的机械装卸循环冷却过程; 图2显示了一个典型elastocaloric冷却循环中，Brayton循环以下。在热源和冷之间的热传递，卸SMA发生在较低的温度水平。在下一阶段，将SMA处于无接触状态和快速，绝热加载导致SMA的显著温度上升。在SMA的恒应变热SMA和散热器之间发生后续的热传递。在传热完成后，快速，绝热卸载导致下面的热源的温度在SMA的显著温度下降，于是下一个冷却Çycle和与热源可以开始传热。该elastocaloric冷却过程的效率取决于所要求的机械加工和吸收的热量。 首先，实验期间拉伸试验监测温度场通过Shaw 等人6,7进行，目的是调查的局部温度峰值期间以不同的速率的SMA条和电线的拉伸试验的形成。应用实验方法，通过热成像测量手段相结合的机械参数（应力，应变和应变率）与同时采集温度场的测量。期间的SMA样品用拉力试验机的装卸，红外（IR）照相机被用来获取在SMA样品的红外图像。这种方法使应变率相关地层温度峰的调查。上的温度分布的测量样品为的elastocaloric影响调查和材料的冷却性能的测定非常重要的。当地温度测量 - 通过施加接触温度测量 - 是不是为了表征材料的冷却性能就足够了。温度场的测量也使用了崔等人 8的镍钛丝elastocaloric影响的研究。此外，Ossmer 等 9,10表明热成像的温度测量也适用于基于薄膜在镍-钛elastocaloric影响进行调查，其所需的IR照相机的高帧率绝热相变的在高应变的调查率。这个技术允许elastocaloric量的调查和温度分布的均匀性，这对基于固态传热和一个显著影响elastocaloric流程效率。 该材料的冷却效率可以通过计算基于所述应力/应变测量以及热（它可被确定考虑到温度变化和材料的热容量）所需的工作来确定。然而，实验方法无法使elastocaloric材料的工艺条件下进行调查。这包括SMA和一个热源，它具有上的冷却效果的效率一显著影响之间的热传递。 的冷却过程中的条件的材料特性和elastocaloric冷却过程的调查需要测试装备使基于固态的热传递，这是不能由任何现有的商用系统进行调查。为此，一种新的测试平台已经研制成功。测试装备设置在两个级别， 如图3的UPPEr级别允许基本elastocaloric材料特性和初始训练程序，类似于先前描述的方法（参见图4）。设置装有能够装载的线性直接驱动，并在应变速率卸SMA高达1秒-1（参见图5）。线性直接驱动使样品与最多至1.8mm 2的横截面的调查，而典型的样品长度为90毫米。线性直接驱动的优点是高的速度和高的加速度 - 相反其通常用于拉伸试验滚珠丝杠驱动器。另外，一个负载传感器，以及所述线性驱动器的集成的位置测量系统，提供机械测量数据。高分辨率红外照相机（1280×1024个像素）被用于测量的SMA高达400赫兹的温度分布（在所要求的温度范围内）。显微镜透镜的与资源的使用15微米/像素的olution使局部温度影响的调查。测试装备的较低级别包含一种机制，允许对交替SMA和热源/散热器之间的热传导（ 见图6和7）。在较低的水平线性直接驱动热源向SMA之间，并从SMA到散热器开关，而气压缸升降机和降低热源/散热器（请参阅图8）。每个致动器可以独立控制允许​​不同的冷却过程变化的调查。综合测量系统使力学参数测量:执行器的位置，致动器速度，SMA装逼，SMA和热源/热传递过程中片之间的接触力以及热参数（ 即温度热源/汇，温度分布内在SMA的表面与热源/罪上K）。科学检测平台的更详细的描述在Schmidt 等 11中给出。 <img alt="图5" src="/files/ftp_upload/53626/53626fig5.jpg" /> 图5.方案的试验台的上水平的用于装载和具有集成位置测量系统在SMA样品卸线性直接驱动。对于拉伸力测量的测力传感器，以及用于温度分布收购高分辨率红外照相机（1280×1024像素）。 <img alt="图7" src="/files/ftp_upload/53626/53626fig7.jpg" /> 图7.方案测试装备的较低级别的线性直接驱动为散热器和热源之间切换。气压缸使SMA样品和热源/散热器之间的接触;温度传感器已经被集成在散热片/苏RCE测量块的核心温度。用于测量SMA和热源之间的接触力的压缩负载单元/汇集成在传热机理和在该方案中不可见。 该试验台允许不同的合金成分和样本的大小以及几何形状（薄带，电线）的调查。此外，设置使elastocaloric材料和冷却过程的全面调查。先前描述的实验可以进行和执行将要描述的一步一步在该手稿的协议部分。 材质稳定: 稳定的物质的行为是在冷却系统中使用elastocaloric材料是重要的。为此，一个机械稳定过程被应用。在此过程中的材料通过机械装卸周期，并执行相从奥氏体转变为马氏体。该材料的稳定表现出强烈的率相关。高负荷率导致材料，这是由相变的潜热引起的温度变化。此温度变化对材料稳定化的类似的影响，如在各种温度下12-15做机械训练周期。除了 ​​众所周知的机械13和热量16稳定，热材料稳定化，可以与设计的设置通过施加热成像17观察到。 材料特性: 初始机械训练过程后，该材料示出了稳定的机械，热和热行为允许elastocaloric材料性质来表征。因此，而进行以不同的速率机械循环，与此相反的训练过程中，elastocaloric表征包括装卸后持有阶段。为保持阶段的持续时间，直到再次达到环境温度水平将SMA应变保持恒定。这种类型的实验是必需的，以便确定卸，从环境温度的水平，以及所述材料的效率开始后的最低达到温度。的局部温度峰值速率依赖性形成可观察到的，具有较高的速率，导致了越来越均匀的温度分布。此外，通过增加变形速度，温度变化同样会增加，直至绝热条件得以实现。该材料的效率可以通过计算卸货时所需的机械功，基于绝热试验的力 - 位移图中，以及在可吸收的热的，基于所述材料的平均温度的变化和样品的热容量来确定。 Elastocaloric冷却过程: 形状记忆合金的工艺条件下的冷却效率进行调查，需要在SMA冷却介质和热源，以及一个热沉之间的热传递。为了这个目的，在SMA处于与固态热源（以下绝热卸载）和散热器（以下绝热装载）接触。该过程的效率强烈地依赖于过程控制和热边界条件。冷却过程的全面调查要求控制参数的变化，以确定最有效的过程控制。的参数对工艺性能的各个影响（接触时间，SMA应变，SMA应变率，接触相（装载/卸载阶段或以下）和接触力期间接触）具有可查。此外，改变热边界条件，通过增加冷却循环的数目的影响有加以考虑。 模型验证: 一个热机械耦合材料模型，能够再现冷却循环过程中的机械和热材料行为的发展，是一种新型的冷却技术的发展至关重要。该模型允许通过减少实验和材料的开发工作，材料和工艺优化。验证需要一个稳定的材料，以产生所需的机械材料的输入数据（奥氏体的弹性模量和马氏体相，所述机械滞后的宽度以及转化株）的初始温拉伸试验。模型的验证需要的以不同的速率拉伸试验的基础上进行。该模型所需要的热量输入的数据可以通过以下的机械实验差示扫描量热法（DSC）来测定。在DSC测量必须AF执行之三为了测量稳定样品的热量的材料特性的机械测试。

<table border="0" cellpadding="0" cellspacing="0" width="1134">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:273px;">Linear direct drives</td>
			<td style="width:116px;">ESR-Pollmeier</td>
			<td style="width:179px;">ML 1418-U5-W1</td>
			<td style="width:567px;">SMA loading/unloading; heat transfer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pneumatic cylinder&#160;</td>
			<td>Festo</td>
			<td>ADNGF-40 574031</td>
			<td>Contact between heat source/sink and SMA</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Inductive position measurement system&#160;</td>
			<td>AMO</td>
			<td>LMKA-1101.1NN-1.0-0</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:273px;">Tension and compression load cell</td>
			<td style="width:116px;">Futek</td>
			<td>LCF451; FSH02241</td>
			<td>SMA force</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:273px;">Compression load cell</td>
			<td style="width:116px;">Futek</td>
			<td>LTH300; FSH00297</td>
			<td>Contact force</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:273px;">IR camera</td>
			<td style="width:116px;">Infra Tec</td>
			<td>Image IR 9360; M91129</td>
			<td>1280x1024 pixels; Maximum frame rate 3200 Hz&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:273px;">Real-Time Controller&#160;</td>
			<td style="width:116px;">National Instruments</td>
			<td style="width:179px;">NI CompactRIO-9074</td>
			<td>Data acquisiton and control system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:273px;">Camera varnish</td>
			<td style="width:116px;">Tetenal</td>
			<td align="right" style="width:179px;">105202</td>
			<td></td>
		</tr>
	</tbody>
</table>

experimental methods for investigation of shape memory based elastocaloric cooling processes and model validation

使用elastocaloric冷却过程必须是环境友好的替代传统的蒸汽压缩基于冷却过程中的潜在的形状记忆合金（SMA）。基于镍钛（镍钛）合金体系，特别是显示大elastocaloric影响。此外，表现出大的潜热是一种有效的基于固态的冷却过程的发展的必要的材料特性。一个科学试验装置已被设计为调查这些进程和形状记忆合金的elastocaloric影响。实现的测试​​装备使一个SMA的机械装卸循环的独立控制，以及SMA冷却元件和热源/散热器之间的热传导。该试验台配有能够机械和热工参数同步测量的综合监测体系。除了确定从属进程机械工作中，该系统还可以使measuremen的通过使用一个高性能的红外照相机的elastocaloric冷却效果热热量方面吨。这个组合是特别感兴趣的，因为它允许的定位和速度的影响的插图 - 待冷却用于从介质高效的热传递都重要。 提出的工作描述的实验方法，以确定在不同的材料和样品的几何形状elastocaloric材料特性。此外，试验台被用于研究不同的冷却过程的变化。引进的分析方法使材料，工艺的差异化的考虑和相关的边界条件影响的处理效率。与模拟结果（一热机械耦合有限元模型的）实验数据的比较可以更好地了解elastocaloric效果的基本物理学。此外，实验结果，以及在发现巴sed的模拟结果，被用来改善材料性能。

材质稳定（训练）: 图9示出的50训练周期的应力/应变图。所调查的样品是镍钛丝带与A =1.45毫米2的横截面。 1×10 -3秒的施加应变速率-1导致的ΔT= 12.2 K的温度上升的平均温度上升对稳定化效果的显著影响12- 14;除了 ​​机械稳定，热稳定化可以观察为好。 ...

Watch this Scientific Journal Video about Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation at JoVE.com

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

基于形状记忆调查Elastocaloric冷却过程和模型验证实验方法

Experimental methods for investigation of solid state cooling processes and characterization of elastocaloric material properties of Shape Memory Alloys (SMA) are presented. A custom-built test rig has been designed for controlling and comprehensive monitoring of elastocaloric cooling processes. Furthermore, it provides a validation platform for thermomechanically coupled modeling approaches.

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor ...

experimental-methods-for-investigation-shape-memory-based

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

11.0K 次观看.  Saarland University. Experimental methods for investigation of solid state cooling processes and characterization of elastocaloric material properties of Shape Memory Alloys (SMA) are presented. A custom-built test rig has been designed for controlling and comprehensive monitoring of elastocaloric cooling processes. Furthermore, it provides a validation platform for thermomechanically coupled modeling approaches. 

视频: Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

控制的大小，形状和稳定性超分子聚合物在水

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

科研

工程学

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

梯度回波量子存储在温暖的原子蒸气

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

对于新材料的低温磁输运测量先进的实验方法

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

SSVEP-based Experimental Procedure for Brain-Robot Interaction with Humanoid Robots

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives. The overall goal of our method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, and Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots.
This is achieved by first placing EEG electrodes on a human subject to measure the brain responses through an EEG data acquisition system. A user interface is used to elicit SSVEP responses and to display video feedback in the closed-loop control experiments. The second step is to record the EEG signals of first-time subjects, to analyze their SSVEP features offline, and to train the classifier for each subject. Next, the Online Signal Processor and the Robot Controller are configured for the online control of a humanoid robot. As the final step, the subject completes three specific closed-loop control experiments within different environments to evaluate the brain-robot interaction performance.
The advantage of this approach is its reliability and flexibility because it is developed by integrating multiple software programs. The results show that using this approach, the subject is capable of interacting with the humanoid robot via brain signals. This allows the mind-controlled humanoid robot to perform typical tasks that are popular in robotic research and are helpful in assisting the disabled.

The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs to enable the study of brain-robot interaction with humanoid robots, which is prospective in assisting the sick and elderly as well as performing unsanitary or dangerous jobs.

SSVEP基础实验步骤与人形机器人脑机器人互动

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

板料成形过程的知识基于云的有限元模拟

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the ...

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

This protocol describes the operation of a liquid flow specimen holder for scanning transmission electron microscopy of AuNPs in water, as used for the observation of nanoscale dynamic processes.

使用扫描透射电子显微镜研究纳米大小的物体的动态过程中的液体

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a ...

Experimental Procedure for Warm Spinning of Cast Aluminum Components

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to improve material properties. With a wide array of processing parameters which can affect both the shape attained and resulting material properties, this type of processing is notoriously difficult to commission. A simplified, light-duty version of the process has been designed and implemented for full-size automotive wheels. The apparatus is intended to assist in understanding the deformation mechanisms and the material response to this type of processing. An experimental protocol has been developed to prepare for, and subsequently perform forming trials and is described for as-cast A356 wheel blanks. The thermal profile attained, along with instrumentation details are provided. Similitude with full-scale forming operations which impart significantly more deformation at faster rates is discussed.

An experimental protocol for instrumented warm rotary forming of cast aluminum alloys employing a bespoke industrially scaled apparatus is presented. Experimental considerations including thermal and mechanical effects are discussed, as well as similitude with full-scale processing of automotive wheels.

铸铝零部件的暖纺纱实验程序

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

使用激光投射光热法构造加热的地下缺陷定位

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...