- [客户回访]蒸蒸日上的国产晶振市场里陶振是那样的泰然处之2018年03月01日 14:07
对很多接触晶振的朋友来说肯能很少听到陶瓷晶振这个名词,一些朋友可能早就开始不再需要接触陶瓷晶振了,现在的晶振市场可以说充斥着大多数名词都是石英晶振,石英晶体,无源晶振,有源晶振,石英晶体谐振器,石英晶体振荡器,</span>32.768K</span>晶体,贴片晶振,温补晶振,压控晶振,压控温补晶振,恒温晶体振荡器,差分晶振,可编程振荡器,</span>32.768K</span>有源晶振等等,这些词汇相信每个与晶振行业先接触的朋友都已耳熟能详了。</span> </p>
- 阅读(91)
- [技术支持]石英晶振的弹性性质以及应变分析讲解2018年03月01日 08:48
在外力作用下</span>,</span>物体的大小和形状都要发生变化</span>,</span>通常称之为形变。如果外力撤消后</span>,</span>物体能恢复原状</span>,</span>则这种性质称为物体的弹性</span>;</span>如果外力撤消后</span>,</span>物体不能恢复原状</span>,</span>则这种性质就称为物体的塑性。自然界既不存在完全弹性的物体</span>,</span>也不存在完全塑性的物体。对于任何物体</span>,</span>当外力小时</span>,</span>形变也小</span>,</span>外力撤消后</span>,</span>物体可完全复原</span>;</span>当外力大时</span>,</span>形变也大。若外力过大</span>,</span>形变超过一定限度</span>,</span>物体就不会复原了。这就说明</span>,</span>物体有一定的弹性限度</span>,</span>超过这个限度就变成塑性。与压电有关的问题</span>,</span>都属于弹性限度范围内的问题。因此</span>,</span>这里仅讨论石英晶振</a></b>晶体的弹性性质。</span> </p>
一、应力</span></b> </p>
选两根长度相等</span>,</span>粗细不同的橡皮绳</span>,</span>当这两根橡皮绳受到相同的拉力作用时</span>,</span>显然</span>,</span>细橡皮绳比粗橡皮绳拉得长一些。为什么在相同的外力作用下</span>,</span>它们的伸长量不一样呢</span>?</span>这是因为两根橡皮绳的粗细不一样</span>,</span>也就是横截面的大小不样。由此可见</span>,</span>在拉力的作用下</span>,</span>物体的伸长量不仅与力的大小有关</span>,</span>而且还与石英晶振,贴片晶振</a></b>等物体的横截面的大小有关。为了计入横截面大小的影响</span>,</span>引入单位面积的作用力</span>(</span>即应力</span>)</span>这个概念</span>,</span>它的数学表达式为</span>:</span> </p>
/></span> </p>
式中</span>,T</span>为应力</span>,F</span>为作用力</span>,A</span>为横截面</span>(</span>即力的作用面积</span>)</span>。通常规定作用力为拉力时</span>,T>0,</span>作用力为压力时</span>,T<0</span>。</span> </p>
二、应变</span> </p>
选择两根长度不等</span>,</span>但粗细相同的橡皮绳</span>,</span>当这两根橡皮绳受到相同的拉力作用时</span>,</span>它们的应力相同</span>,</span>而伸长量不同</span>,</span>即长橡皮绳比短橡皮绳拉得长一些。由此可见</span>,石英晶体振荡器,石英晶振</a>,</span>物体的伸长量不仅与应力有关</span>,</span>而且还与原来的长度有关。为了计入长度的影响</span>,</span>引入单位长度的伸长量</span>(</span>即应变</span>)</span>这个概念。它的数学表达式为</span> </p>
/></span> </p>
式中</span>,S</span>为应变</span>,l</span>为原长</span>,</span>△</span>l</span>为伸长量</span>,</span>△</span>l</span>为单位长度的伸长量</span>(</span>或相对伸长量</span>)</span>。</span> </p>
三、正应力与正应变</span> </p>
如图</span>2.2.1(a)</span>所示的小方片</span>,</span>当它受到</span>x</span>方向的应力作用时</span>,</span>除在</span>x</span>方向产生伸长外</span>,</span>同时在</span>y</span>方向也产生收缩</span>,</span>如图</span>2.2.1(b)</span>所示。同样</span>,</span>当小方片受到</span>y</span>方向的应力作用时</span>,</span>除了在</span>y</span>方向产生伸长外</span>,</span>同时在</span>x</span>方向也产生收缩</span>.如图</span>2.2.1(c)</span>所示。上述</span> </p>