PZFlex is Sophisticated Modeling for Complexity

By Jim Romeo

Paul Reynolds of Weidlinger Associates, Inc.

PZFlex—developed by Weidlinger Associates of Mountain View,  CA—uses finite element analysis (FEA) to quickly solve complex problems in everything from the design of sensors and medical ultrasound components to aerospace and the oil and gas industry. We spoke to Paul Reynolds, Ph.D., who works at Wiedlinger and collaborates on piezoelectric and electromagnetic projects with leading industry and academic researchers worldwide in a variety of fields, about PZFlex and its use as a simulation tool for design applications.

  Reynolds received his advanced and undergraduate degrees from the University of Strathclyde, Scotland, UK, in ultrasonics and mechanical/electrical engineering. As an associate of Weidlinger’s Northern California office, he is responsible for PZFlex development, consulting, and sales.

Can you give us an overview of PZFlex, what it is, and how it has developed?
Reynolds: PZFlex was specifically written to handle wave-propagation problems. In the early 1980s, when FLEX was first started, the typical FEA approaches of the day could not solve some of the problems the Department of Defense wanted to look into, such as blast and impact (both of which involve highly nonlinear waves). Weidlinger Associates staff therefore used alternative solution methods termed “explicit,” which allowed models hundreds of times larger and faster than before, for the class of problem investigated. This is how FLEX was born.

  Throughout the 1980s, Weidlinger used FLEX to analyze a wide range of DoD problems, then in 1991 realized that the ultrasound medical imaging and the naval SONAR communities both used wave propagation heavily in their applications and depended on piezoelectric devices. So we added piezoelectric solvers to FLEX, and PZFlex was born.

  Since then, PZFlex has been adopted by all the major ultrasound imaging manufacturers in the world and has expanded into a wide range of markets—actuators, sensors, telecommunications, and nondestructive testing, to name a few. The common link among these markets being piezoelectric and ultrasound wave propagation.

What are some of the specific applications of the product,  and how is it unique among Similar solutions?
Reynolds: The largest markets for PZFlex are the medical ultrasound community and the SONAR community. The devices used to generate ultrasound images of babies in the womb are designed with PZFlex. One common application today is high-intensity focused ultrasound (HIFU), where ultrasound energy is intensely focused to a point inside the human body, and as with a magnifying glass in the sun, tremendous heat is generated at that focus and tissue is destroyed. This allows for noninvasive surgery, such as for removal of tumors, and is a heavily investigated field today. Prostate cancer is the cancer most commonly treated in this manner, but it is expanding to more complex and difficult cancers.

  PZFlex is used in the study of this field, as well as the development of the devices to perform the surgery. PZFlex alone has the capability to simulate the therapy device with its piezoelectric drive section,  the nonlinear ultrasound wave propagation through the layers of tissue, and the heat generation based on that propagation. The scale of models that PZFlex can solve, combined with the fact it has been specifically written for piezoelectric and ultrasound problems, mean we can tackle problems other software has to move out of its “sweet spot” to an arena where it does not excel.

What should design engineers and teams know about virtual prototyping software that they might not already?
Reynolds: Advancements in the accuracy and efficiency of virtual prototyping that PZFlex brings, combined with the advanced and low-cost hardware, not only drastically reduce time to market for any piezoelectric or ultrasound product, but improve the understanding of devices that would be too complex to simulate by any other method. The virtual prototyping method is so powerful and accurate these days, that it can even show up flaws in the manufacturing process, such as weak bonds or a bad batch of material, in a way that was difficult to do even a few years ago.

How much has virtual prototyping changed over the past five years?
Reynolds: The last five years have seen personal computing hardware reach a point where affordable hardware and operating systems, when paired with an efficient tool like PZFlex, can tackle most of the problems designers want to look at. This affordable virtual prototyping—once something only the biggest players could do—puts world-class development and experimental facilities in the hands of a single-person company operating out of the home,  leveling the playing field and allowing everyone to compete and create the next big breakthrough.

  Engineers, researchers, and designers have understood the benefits of virtual prototyping for quite a while, but it has often proved difficult to persuade management of the benefits when an upfront investment in software, hardware, and training is needed. In recent years, as both competition and cost of raw materials have increased, and as the track record of simulation tools like PZFlex has lengthened and becomes more persuasive,  inviting additional competition from one-person shops, managers have begun to see the cost benefits of decreased cycle time and reduction in the manufacture of prototypes.

What distinct benefits does prototyping software bring to the design cycle?
Reynolds:  I would say that virtual prototyping allows you to “make more mistakes, faster.” Mistakes in any development cycle are not only good, they are essential. It’s how we learn, how we see what doesn’t work so we can make something that does. When each mistake costs weeks ... and tens or hundreds of thousands of dollars ... as in traditional prototyping approaches, it is easy to see why a conservative mindset and cautious development are warranted.

  Now imagine instead that the new design costs you nothing,  and you simply have to wait a few minutes to a few hours to see how the device performed. Virtual prototyping frees the designer from the old constraints and allows any concept imaginable to be built, tested, and quantified almost without regard to budget.

Based on your relationships with designers, what are they most interested in with regard to design software?
Reynolds:  In today’s rapidly moving and demanding markets, many engineers wear multiple hats and work on multiple projects. Often they are moved to new projects on which they are expected to be experts in days. They want the tools to design their devices quickly, and the support behind those tools so that they know the tool does what it is supposed to. Also, designers want something that is not only fast,  accurate, and reliable, they want to know that they have access to a wealth of knowledge both on the simulation and on the piezoelectric/ultrasound aspects of their project.

  Another critical aspect is in the building of the models and importation into the simulation package. Designers do not want to have to learn yet another package or to rebuild their existing models from scratch; rapid importation is key. This is why PZFlex now uses SolidWorks, the leading solid modeling tool, as our primary model-development interface.

What Are the greatest challenges for design engineers and how will software and technology meet them?
Reynolds:  The last few years have seen enormous changes in how businesses operate, and globalization means engineers in wealthy regions such as North America, Europe,  and Japan can no longer compete on price, either for their labor or for manufacturing. Attempts to maintain the old business models in the face of this cannot succeed, so we must look to new avenues of high-margin business. Like engineers of the past, when their market became saturated with low-cost competitors, today’s design engineer must move beyond the basic design requirements and offer a higher-value package. Faster turnarounds, more detailed analyses, colorful and effective data presentation, and an integrated design process from concept through to engineering drawing and product delivery are what customers are willing to pay extra for.

  Virtual prototyping tools like PZFlex enable the designer to produce a final design more quickly, understand the device’s features better,  explain benefits to a customer simply and quickly and both build models and generate engineering drawings.

How has your virtual prototyping software been used recently?
Reynolds:  One of the best examples is the Ultreo ultrasonic toothbrush. Unlike the normal electric toothbrush “vibrating head” method, the Ultreo design has a real ultrasound transducer in the head, which cleans teeth through ultrasound mechanical action, even in areas bristles can’t reach. The output requirements for power and frequency were very reasonable, but fitting them into the space of a toothbrush head was quite a challenge. The development team came to us early in the cycle,  which allowed the use of PZFlex almost from day one and the testing of a range of possibilities with virtual prototyping until the best option was found. They moved from concept to mass production and product delivery in an astonishingly short period of time, amazing even Weidlinger staff, and we are proud that PZFlex played a part in that.

More Info:
Weidlinger Associates, Inc.
Mountain View, CA

Jim Romeo is a freelance writer specializing in industrial technology topics and can be reached at jimromeo.net. To comment on this interview, send e-mail to [email protected].