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Project Listing

The following examples illustrate the services we have provided to clients.

Anisotropy of 3D-Printed Polymers

Technical Challenge: The additive manufacturing (AM) industry is maturing at an exciting pace, and a wide variety of 3D-printing techniques, raw materials, and design tools are now available. To date, engineers have employed AM primarily for rapid prototyping. However, for those industries that can derive value from highly complex part geometries, the true goal remains to employ AM for the production of reliable end-use parts.

Bioabsorbable Coronary Stent Design

Technical Challenge: Bioabsorbable materials, such as polylactic acid (PLA), are finding increasing applications in medical devices. These polymers exhibit a nonlinear anisotropic viscoplastic response when deformed, which requires a sophisticated material model for accurate finite element predictions. Veryst was asked to provide a material model to improve predications of PLA stent stresses and strains.

Broken Rail Train Derailment

Technical Challenge: A train derails with an ensuing fire and evacuation of neighborhood. What was the root cause of the derailment?

Bubble Entrapment in Microchannels

Technical Challenge: Entrapment of bubbles in microfluidic devices can distort the fluid flow and negatively impact device performance. For example, bubbles can obstruct the formation of jets in inkjet printers and can cause faulty reporting for sensors embedded in microchannels. In some cases, the presence of bubbles cannot be completely avoided. In these cases the bubbles ideally should flow through the channel without entrapment. The likelihood of bubble entrapment depends on the geometry of the channel, the flow characteristics, and the surface properties of the microchannel walls.

Calrod Thermal Analysis

Technical Challenge: Calrods are tubular heating elements that convert electricity into heat via Joule heating. They are used in appliances because of their high power density. They are frequently modeled as uniform heating elements. This modeling approach cannot capture the temperature variations and the thermal stresses in the Calrod, which is necessary for predicting actual performance.

Cell phone drop test

Technical Challenge: Biodegradable polymers are becoming increasingly attractive for consumer product applications such as electronic devices and disposable packaging. Modeling these materials during impact is challenging due to the complexity of the physical event and the scarcity of appropriate material models for biodegradable polymers.

CFD Ventilation of a Hospital Room

Technical Challenge: Efficient ventilation can contribute to reducing the energy consumption of buildings and minimize the risk of airborne infection in hospital rooms. In this problem we investigate ventilation in a hospital room containing a patient, a doctor, a bed, a wardrobe, a lamp, medical equipment, an inlet and exhaust. We account for both forced and natural ventilation as well as the flow of bacteria particles originating from a sick patient. Layout of the room is shown in figure 1. Ventilation rate is 6 ACH (Air Change per Hour) for health care facilities, per ASHRAE Standard 170.

Cohesive Zone Model Calibration

Technical Challenge: Cohesive zone modeling (CZM) is a powerful tool for predicting delamination in adhesively bonded structures and is widely implemented in commercial finite element codes. In the CZM approach (Figure 1), fracture is assumed to occur by progressive separation of the crack surfaces ahead of the crack tip. The crack grows when the crack separation reaches a critical value, δC. The key input into any cohesive zone model is the traction-separation law, σ(δ). The successful use of cohesive zone modeling relies upon this traction-separation law to accurately represent the fracture of the material or interface being modeled. The traction-separation law therefore must be calibrated experimentally.

Composite High Strain Rate Testing

Technical Challenge: There is a shortage of high strain rate, or impact, mechanical test data for fiber reinforced thermoplastics, whether the reinforced polymer is continuously formed as in pultrusion or is formed as discrete injection molded components. Understanding these materials’ impact response as a function of fiber direction is important in automotive applications for crashworthiness and in consumer product uses for drop and impact resistance.

Cranial Perforators

Technical Challenge: Surgeons were returning perforators because of surface imperfections. Veryst was retained to identify the source of the surface features.

Delamination in Microfluidic Valves

Technical Challenge: A commonly encountered failure mode in microfluidic devices is delamination between adjacent device layers. Thus the design of robust microfluidic structures requires not only an analysis of the operating pressures required for device function, but the pressures at which delamination will occur. One class of components susceptible to delamination is pneumatic valves, which consist of control and flow channels separated by a thin elastomeric membrane, illustrated in Figure 1. Pressurization of the control layer deflects the membrane into the flow channel, closing the valve. This pressurization also results in the development of tensile stress at the interface between the valve membrane and the control channel substrate which can lead to delamination.

Design of Reinforced Hoses

Technical Challenge: A high-strength reinforced hose failed in service under normal operating conditions well before its intended design life. Inspections of the subject hose revealed that failure was mainly due to delamination.

Elastomer Foam Vibration Damper

Technical Challenge: Many consumer applications need vibration damping components to protect electronics or other sensitive materials. Various foam materials are commonly used in these applications due to their low price and good vibration damping characteristics. Most foam components, however, have a highly nonlinear viscoelastic response that requires a suitable material model for accurate finite element predictions.

Fatigue Failure of a Plastic Lever

Technical Challenge: A plastic lever on a consumer product failed unexpectedly in service at the fulcrum pin. The lever was subjected to repeated loading in service.

FEA of Absorbable PLLA Bone Screw

Technical Challenge: Absorbable (Poly-L-lactic acid) bone screws are used commonly in Anterior cruciate ligament (ACL) reconstruction, where polymer screws attach the tendon graft to the tibia, absorbing back into the body as the tendon naturally attaches to the bone. Proper bone screw design includes analysis of the holding force of the screw and the stresses within the screw. Nonlinear deformation and relaxation within the polymer however makes prediction of these forces and stresses over time very difficult, complicating their design.

Golf Ball Impact Simulation

Technical Challenge: The United States Golf Association sets certification criteria of golf balls and club faces (i.e. groove geometries) based on measured characteristics of the ball’s impact response, such as velocity and spin rate. Ball and club designers attempt to “tune” these characteristics for improved performance within these guidelines. There is a need for accurate, predictive simulations to understand how changes in material response and geometry of the ball and/or club face can affect these variables.

Guidewire Entanglement

Technical Challenge: A guidewire became entangled in a coronary stent during a routine angioplasty/stenting procedure. There was a question as to whether the guidewire was appropriately designed.

High Rate Temperature Response of Polymers

Technical Challenge: Modern materials exhibit time- and temperature-dependent effects that must be taken into account during product development and design. Products may be over-designed leading to higher costs or may fail during normal use scenarios if only room temperature properties are considered. Materials also exhibit changes in initial modulus, failure stress and strain, and may undergo ductile to brittle transitions. Good design practice therefore includes determining high rate properties and calibrating material models at service temperatures.

High Strain Rate Testing of Polymers

Technical Challenge: Polymeric materials are frequently used in impact applications where strain rates can exceed 1000/s (i.e. helmets, protective eyewear, enclosures for electronics etc.). Many of the materials used for such applications (polycarbonate, ABS etc.) are known to be strain rate-dependent. However, there is frequently little to no information about the polymer behavior as a function of strain rate. Furthermore, there are few constitutive models available in commercial finite element codes that are capable of adequately capturing the nonlinear, viscoplastic flow behavior of these materials over several decades of strain rate.

High temperature polymer behavior

Technical Challenge: Polymeric materials are used increasingly in elevated temperature applications such as seals and biomedical implants. Many polymers’ mechanical behavior at elevated temperatures is not available or inadequate to make informed design decisions. To meet this need, design and simulation engineers require mechanical testing at a range of temperatures.

Immersed Beam Vibration

Technical Challenge: The natural frequencies of thin structures such as beams, plates or shells change when immersed in a fluid. The fluid also affects mode shapes and provides additional damping. This phenomenon affects structures across a wide range of industries and sizes, from micro-scale structures such as MEMS actuators to larger structures such as ships.

Impact Fracture of Adhesives

Technical Challenge: Measuring the fracture toughness of adhesive joints under impact is important for understanding the performance of adhesively bonded structures in numerous industries. Predicting the crashworthiness of bonded automotive structures and the drop-resistance of hand held electronics are just two examples. However, getting a good measure of toughness at impact rates can be difficult due to the dynamic nature of the experiments.

Infant incubator

Technical Challenge: Prematurely born babies (neonates) are kept in an infant incubator until they can maintain their temperature on their own. The main environmental factor affecting a premature neonate is thermo-neutrality, as the baby is incapable of regulating and maintaining his/her body temperature at a constant level. Significant temperature differences inside an infant incubator therefore may cause hypothermia. The technical challenge is to optimize infant incubator design in order to minimize internal temperature variations.

Insufflation Analysis

Technical Challenge: Veryst was retained to compare two gas humidification devices used with insufflation equipment.

Laminar Static Mixer Analysis

Technical Challenge: Laminar static mixers work by periodically dividing and recombining fluids until they are well mixed. The performance of these mixers is impossible to analyze with a pure CFD approach due to the limited molecular diffusion between the mixed fluids.

LED Light Bulb Heat Transfer Simulation

Technical Challenge:
Light-emitting diode (LED) bulbs offer higher energy efficiency and longer service life than fluorescent and incandescent lamps. However, both the efficiency and life of an LED will drop when operated at high temperature. Manufacturers design heat sinks with cooling fins into the body of the bulb to reduce the operating temperature. Given the wide range of possible shapes and sizes of heat sinks, a rapid and effective tool is needed to compare design alternatives and estimate LED temperatures.

Microfluidic Mixer Concentration Profile

Technical Challenge: Microfluidic mixers produce highly accurate solute mixing between fluid channels by cross-stream diffusion in laminar viscous dominated flow. What is the appropriate mixer configuration to achieve a desired mixing between pure and salt water channels?

Multiphysics Analysis of MEMS Switch

Technical Challenge: The responses of MEMS actuators and switches immersed in fluids differ from those in a vacuum. Fluid inertia and viscosity delay the switch response in opening and closing, and fluid viscosity causes energy losses (squeeze film damping).

Osteotome Fracture

Technical Challenge: An osteotome unexpectedly failed during a plastic surgery operation. Veryst was hired to explain the failure.

PEEK Temperature Dependence

Technical Challenge: Polyether ether ketone (PEEK) materials are increasingly used in industry, including seals in oil and gas equipment and as a bearing surface for orthopedic implants such as knee and hip joints. In many of these applications, the polymer is subjected to loading cycles at elevated temperatures. Thus, accurate simulations of PEEK behavior require the constitutive model used for the material to capture time- and temperature-dependent behavior. Despite this need, there are few material models available in commercial software codes capable of capturing the combined effects of temperature, strain rate and time.

Peeling of a Soft Polymer Film

Technical Challenge: The peel test is widely used to measure the adhesion of thin, compliant films to rigid substrates. An accurate model of the peeling mechanics for the material being tested is required to extract the interface adhesion energy.

Peristaltic Pump Fluid - Structure Interaction

Technical Challenge: Peristaltic pumps move fluid by squeezing an elastomeric tube causing the fluid inside the tube to follow the motion of the roller. They are valuable for pumping aggressive fluids that could damage or contaminate rotors or gears and for pumping delicate fluids such as blood. The performance of peristaltic pumps is influenced by tube dimensions, tube material, rotary mechanism, and fluid properties, but the interaction of these factors is not well understood.

Phononic Band Gap Analysis

Technical Challenge: There is a growing demand for applications utilizing periodic band gaps structures. Optimizing the location and width of the band gap is most efficiently performed using an eigenfrequency analysis of the unit periodic cell with Floquet boundary conditions. This analysis requires a complex solver due to the nature of the Floquet boundary conditions (not due to damping). This capability was not readily available in commercial FEA software.

Plastic Clip Failure

Technical Challenge: A plastic clip used to retain a patient support failed, resulting in an occupant death. Veryst was asked to determine the cause of failure.

Polymer Foam Testing and Modeling

Technical Challenge: Polymer foams are complex materials that exhibit drastic sensitivity to applied loading and strain rates. As applied strain rate increases, polymer foam materials stiffen more than bulk polymers, presenting challenges in both testing and modeling. Additionally, foams can exhibit large differences in stress relaxation at different strain rates. Accurately capturing the response of foams is critical to modeling the material for use in Finite Element (FE) simulations, enabling design engineers to optimize foam components.

Polymer Material Models in Different FE Packages

Technical Challenge: Finite Element (FE) simulations play a crucial role in modern engineering design and analysis, enabling engineers to predict and optimize the mechanical response of designed parts prior to creating a prototype. There are three critical inputs to all FE simulations: geometry, defined by the design engineer; loading, dictated by the designed use of the part; and the material model.

RF Tissue Ablation Simulation

Technical Challenge: Radiofrequency (RF) tissue ablation is a minimally invasive treatment commonly used to destroy tumors or alleviate tissue blockages. The simulation of RF tissue ablation helps device designers predict the thermal and electric fields in the affected tissue. There are, however, challenges in properly setting up the coupled multiphysics analysis and in determining realistic inputs to the model.

Sea Floor Energy Harvesting

Technical Challenge: Veryst Engineering provides energy harvesting design solutions for a variety of industries. One example is harvesting energy from constant, low speed ocean floor currents to power ocean floor sensors. Such sensors are used in naval applications, environmental monitoring, earthquake monitoring and oil exploration.

Small Sample Size Lifetime Prediction

Technical Challenge: How long will a product last? Virtually all reliability engineers must address this question during product development. Yet prediction of accurate product end of life can be hampered by limited data.

Tank Sloshing Simulation

Technical challenge: Sloshing is the motion of a free-surface liquid in a partially filled vessel, experienced in marine, automotive, rail and aerospace industries. During sloshing, the liquid exerts a dynamic force on the surrounding vessel, which may cause leakage, or damage to the vessel or its supporting structure. The sloshing motion is a highly nonlinear and random process depending on vessel motion, liquid depth, liquid properties, and vessel geometry. Resonance also plays a role when the external forcing frequency is close to a natural frequency of the liquid volume. Existing analytical models for predicting the effects of sloshing sometimes offer a reasonable approximation, but their basic assumptions make them invalid for a wide range of applications.

Tempered and Plate Glass Fracture

Technical Challenge: Tempered and plate glass are manufactured to produce very different fracture patterns when they break. The particular mechanisms of fracture are difficult to visualize between the two glass types.

Tire Deformation

Technical Challenge: The behavior of elastomeric materials is controlled by the inherent nonlinear viscoelasticity. The nonlinear behavior makes the material strain-rate dependent and lose energy during cyclic loading (hysteresis). These behaviors are important for many applications, for example when determining the footprint of a tire.

Total Knee Replacement

Technical Challenge: New total joint replacement prostheses often use UHMWPE in load bearing components. Design engineers need to understand the stress and strain distributions in order to extend device life.

Transdermal Drug Delivery

Technical Challenge: Delivery of drugs through skin has become a popular mechanism for delivering long term, controlled dosages of various compounds. A drug is mixed with an adhesive and cast into a patch, which is then applied to the skin.

Transdermal Permeation Enhancers

Technical Challenge: Skin is a very effective barrier and provides resistance to drug delivery. Permeation enhancers are used to improve drug delivery through the skin by altering the structure and dynamics of the skin.
Simulation can be used to study transdermal drug delivery. However, the standard linear diffusion equation does not apply in the case of permeation enhancers, resulting in the need for a new approach to determining the drug delivery rate when enhancers are used.

Underfill Adhesive Flow and Cure

Technical Challenge: The microelectronics packaging industry relies heavily on adhesive bonding to assemble electronic components. The demand for higher manufacturing throughput and lower cost means there is a constant need for advances in adhesives and assembly process technology. One emerging adhesives technology is non-conductive film (NCF), which involves application of an underfill to an entire wafer prior to die singulation and thermocompression bonding. Among the challenges with NCF technology is the need to optimize the adhesive properties and process variables to realize the shortest possible bonding time while, among other factors, creating a properly shaped underfill fillet at the die edge (see Figure 1). A concave fillet shape is critical for device reliability. This optimization is a challenge due to the very short process times, rapid heating rates, and complex chemorheology of NCF materials.
 
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