What you’ll learn:
- The wide application of piezoelectric technology.
- 为什么趋势使小型化设备,同时保留precision present challenges for design engineers.
- 多物理软件工具如何解决设计压电声传感器的固有多物理挑战。
The increasing miniaturization and sophistication of electronic products, ranging from consumer media devices to medical diagnostic tools to defense-related sonar applications, presents a bounty of utility and ease for consumers—and an ongoing challenge for design engineers. These seemingly disparate products (audio/mobile device speakers, certain non-invasive medical devices, and sonar arrays) share in common a reliance on piezoelectric transducers to both generate and receive acoustic signals.
Piezoelectric materials have been valued since the first half of the 20th century for their ability to convert mechanical energy into electrical energy and vice versa. However, 21st century technology demands that these same materials produce more sound or more precise frequencies within smaller and smaller packages, all while utilizing as little energy as possible.
设计包含压电设备的挑战是由于电力，振动和声学的汇合而在自然界内固有的多物理学。因此，设计师必须拥有可以计算其产品中多种物理的工具。
Piezoelectric Material Overview
Piezoelectric materials are materials that can produce electricity due to mechanical stress, such as compression. These materials also can deform when voltage (electricity) is applied. Typical piezoceramic materials, whether non-conductive ceramic or crystal, are placed between two metal plates.
为了产生压电，必须压缩或挤压材料。应用于压电陶瓷材料的机械应力会产生电力。压电效应可以逆转，称为反压电效应。这是通过施加电压来制造压电晶体收缩或扩展的。反压电效应将电能转换为机械能。
在各种各样的日常产品中发现了压电材料。当您按下“咔嗒声”打火机的按钮时，飞跃的火焰通过压电材料的压缩得以实现，从而产生火花。
现在，让我们看一些其他产品，这些产品对设计工程师的挑战更加挑战，因为需要增加较小设备内的产出。
Mics and Speakers
Piezoelectric materials are used extensively in acoustics. Microphones contain piezoelectric crystals that convert the incoming sound waves into signals that are then processed to create outgoing amplified sound. Small speakers, such as those within cell phones and other mobile devices, also are driven by piezoelectric crystals. The device’s battery vibrates the crystal at a frequency that produces sound.
The challenge here is in designing piezoelectric transducers that can produce very-high-quality sound within a small package, and without draining too much of the device’s battery.
Medical Devices
Non-invasive medical devices such as hearing aids also rely on piezoelectrics for a portion of their operation. So, too, does ultrasound technology, which is a major application of piezoelectric material.
In ultrasonics, piezoelectric materials are electrified to create high-frequency sound waves (between 1.5 and 8 MHz) which are able to penetrate bodily tissues. As the waves bounce back, piezoelectric crystals convert the received mechanical energy into electrical energy, sending it back to the ultrasound machine for conversion into an image.
其他医疗设备（例如谐波手术刀）利用压电材料的振动特性在手术过程中削减和捕捉组织。设备内的压电晶体同时产生了同时切割和烧灼所需的动能和热能。
超声设计的挑战集中在确定压电组件的正确形状和材料组成的需求上，以创建超声中使用的非常精确的频率。而且，在谐波手术刀的示例中，设计必须说明加热对设备振动响应的影响。
Sonar
也许可以在声纳应用中找到对压电技术的最广泛，最长期的用途。在第一次世界大战期间，Sonar是压电的第一个商业应用，在两次世界大战之间的时期中，其使用猛增。
如今，所有基于Sonar的系统，包括军事，商业渔民以及许多其他海洋应用程序的系统，都利用含压电的传感器来产生和接收声波。
这似乎很简单，但是设计换能器来通过水而不是空气传播声音可以提出自己的复杂工程挑战。这些应用通常需要压电设备来生成高功率信号以传播长距离，而不会衰减低于可检测的水平。
New Uses
An emerging application of piezoelectric materials is within energy-harvesting technology. Because of the unique properties of piezo materials, they can be successfully used in any application that requires or produces vibration.
In energy harvesting, exogenous vibration produces a mechanical strain to the piezoelectric material that’s converted to electrical energy. That piezo-created energy can then be used to power other components of the device or system.
独立于电池的轮胎压力监测系统（TPM）代表了一个这样的示例。随着车辆的轮胎旋转，会产生机械能。含压电的传感器会收获能量，将其存储并向驾驶员的显示面板发送信号。历史上，TPMS一直是电池供电的，但是对环保电池替代方案的兴趣日益增加，这导致了对压电材料的能源收获潜力的新关注。
Old Discovery, Modern Challenges
Although piezoelectric materials have been utilized for over a century, the current need for their application within smaller and more complex products presents a challenge for design engineers. Choosing the correct materials and designing the right crystal shape are critically important to the functionality of a prototype.
压电材料特性十分复杂are highly intertwined, and material composition matters. Similarly, if the shape of a piezoelectric crystal doesn’t produce the correct resonant frequency, the device won’t work. And, in elegant lockstep with the “Observer Effect,” the very electrification of a piezoelectric crystal deforms its shape while also producing more electricity.
It’s an incredibly complicated feedback loop crying out for a design solution that eliminates the guesswork involved in lengthy build-test prototype processes.
Why Simulation Matters
在处理非线性时，模拟总是有帮助的。它阻止了设计师在太多未知数中建立和测试的无用（通常是预算不可行的）任务。在考虑电声传感器时，电能，机械能和声学的独特组合绝对是非线性的，并且本质上是固有的多物质。
Multiphysics simulation can provide design engineers with the tools to develop products more effectively by enabling them to simulate their device designs within operating conditions. In addition, these simulations may include the entire ecosystem from control circuit to piezoelectric transducer to surrounding acoustic environment. Multiphysics simulations will take into account factors such as:
- The constitutive equations of mechanical and electrical response
- 压电材料特性的极点方向
- Boundary conditions
- Structural mechanics/vibrational heating
As piezoelectric-dependent devices become smaller and more complex to meet the demands of sophisticated consumers (be those individuals or industries), design engineers must have tools that calculate the multiple physics within their products. Multiphysics simulation tools can provide clarity and direction to complicated design challenges.
通过观看使用模拟设计压电声音传感器网络研讨会。
