Delrin Research Articles

Optimal shape selection of pseudo-rigid-body model compliant centrifugal clutch manufactured by thermoplastics using TOPSIS approach

This paper discusses and analyses a compliant centrifugal clutch with different materials. Compliant centrifugal clutch specimens required for investigation are prepared by an injection moulding process. Experiments are conducted based on the experiments designed as per Taguchi’s Design of Experiment (DoE); an L27 Orthogonal Array (OA) is formulated and a multi-response optimisation approach Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) is adopted for optimising torque carrying capacity, wear rate and, contact temperature. Experiments are conducted for three different polymer materials viz., polypropylene (PP), Delrin (DE) and polyurethane (PU) with three different profiles, circular (CR), elliptical (EL) and square fillet (SF), along with varying rotating speeds. The outcome shows that by changing the clutch material and flexure profiles, a substantial variation in torque carrying capacity, wear rate and contact temperature is observed.

Growth medium- and strain-dependent bactericidal efficacy of blue light against Shiga toxin-producing Escherichia coli on food-grade stainless steel and plastic

Shiga toxin-producing Escherichia coli (STEC) are a major group of human pathogens and may persist on both abiotic and biotic surfaces. In this report, two blue-light prototypes were used to evaluate the antimicrobial efficacy against STEC on food processing surfaces (stainless steel and polyoxymethylene plastic). Investigation using a light-bulb prototype (Prototype 1 at 405 nm, 26 mW/cm2) showed significant antimicrobial effects in nutrient deficient condition but not in nutrient rich condition, demonstrating that the presence of organic matters from rich nutrient medium was thought to be light-absorptive and reduce the bactericidal efficacy of blue light, as evident from the lack of bacterial reduction when suspended in cooked meat broth. An advanced (surface-mounted-diode) light panel, Prototype 2 with high light intensity (405 nm; 50 mW/cm2) was able to inactivate a cocktail of seven STEC strains (from seven major serotypes O26, O45, O103, O111, O121, O145 and O157) on type 304 stainless steel (1.66 log10 CFU) and polyoxymethylene plastic (4.25 log10 CFU) at light dosages of 720 and 45 J/cm2, respectively when cells were illuminated in a nutrient-deficient medium (M9 broth). Post-treatment, no STEC cells were recoverable from plastic, both when tested on plates (agar or petrifilms) and by polymerase chain reaction (PCR). In contrast, surviving colonies were identified on samples taken from stainless steel, albeit only four strains could be detected by PCR analysis – those belonging to serotypes O26, O45, O103 and O157 – which indicated that the susceptibility of STEC to blue light varied across the tested strains.

PENGARUH FRAKSI VOLUME PENGUAT 2, 2,5 DAN 3% SERAT BAMBU HAUR DAN FIBERGLASS TERHADAP KEKUATAN TARIK MATRIKS POLIESTER

Against the backdrop of the increasing need for quality composite materials and the development of increasingly advanced composite manufacturing technology in the machinery industry. The aim of this research is to develop composite materials with bamboo fiber reinforcement and glass fiber as an alternative to automotive raw materials to replace plastic. Preparation of composite specimens with each reinforcement with volume fractions of 2%, 2.5%, and 3% and specimens without reinforcement or 0% volume fraction as a comparison.
 The polymer material used is Yukalac 157-EX BQTN polyester as its matrix. With haur bamboo fiber and fiberglass as a reinforcement. Making specimens using the hand lay up method. Tests carried out are composite specimen tensile tests. Tensile testing was carried out using the ASTM D 638M-84 M-1 standard.
 Based on the test results, it was concluded that the effect of fiber volume fraction on the characteristics of composite samples for tensile tests. Composite strengthened by haur bamboo and fiberglass powder at 3% heavy volume fraction has the most ideal characteristics that have a tensile strength of 53.581 MPa, modulus of elasticity of 87.452 MPa and polymer composite material with a strength of haur bamboo and fiberglass powder with a length of 5 mm at 3% reinforcing volume fraction can be used as an alternative to automotive raw materials, namely replacing polyoxymethylene plastic materials for the front bumper.

Study on constancy of CT numbers of SIEMENS Sensation Open CT-simulator

Objective To evaluate the constancy of CT numbers of SIEMENS Sensation Open CT-simulator by analyzing the CT numbers of seven materials obtained from quality assurance (QA) tests. Methods QA tests for SIEMENS Sensation Open CT-simulator were performed with the Catphan504 phantom monthly. The CT images were obtained using three scan protocols (HeadSeq, RT_Head, and RT_Abdomen) for the CTP404 module in the phantom. The DoseLab software was used to analyze the 72 CT images acquired from January 2014 to December 2015, and the CT numbers (Y) of seven materials were obtained. Statistical analysis was performed on the Y data. The mean, standard deviation, maximum, minimum, and range values of Y for seven materials were calculated in three scan protocols. Results The standard deviation values of air, polymethylpentene, low-density polyethylene, polystyrene, acrylic acid, polyoxymethylene resin (Delrin), and polytetrafluoroethylene (Teflon) were as follows: (1) HeadSeq: 0.54, 0.60, 0.82, 0.58, 0.75, 0.66, and 1.83 HU; (2) RT_Head: 0.08, 0.69, 0.86, 0.66, 0.80, 0.89, and 2.49 HU; (3) RT_Abdomen: 0.11, 0.61, 0.76, 0.72, 0.78, 0.96, and 2.56 HU. According to the statistical data, the constancy of CT numbers of the SIEMENS Sensation Open CT-simulator was in good condition in two years. Conclusions The variation of CT numbers of Teflon is the biggest among the seven materials. The relative values of CT numbers between different scan protocols vary with the relative electron density of materials. Key words: Tomography, X-ray Computed; Quality control; Constancy; Catphan phantom

Co-Registration of Bioluminescence Tomography, Computed Tomography, and Magnetic Resonance Imaging for Multimodal In Vivo Stem Cell Tracking.

We present a practical approach for coregistration of bioluminescence tomography (BLT), computed tomography (CT), and magnetic resonance (MR) images. For this, we developed a customized animal shuttle composed of nonfluorescent, MR-compatible Delrin plastic that fits a commercially available MR surface coil. Mouse embryonic stem cells were transfected with the luciferase gene and labeled with superparamagnetic iron oxide nanoparticles. Cells were stereotaxically implanted in the mouse brain and imaged weekly for 4 weeks with bioluminescent imaging (IVIS Spectrum CT scanner) and magnetic resonance imaging (MRI; 11.7 T horizontal bore scanner). Without the use of software coregistration, in vitro phantom studies yielded root-mean-square errors of 7.6 × 10−3, 0.93 mm, and 0.78 mm along the medial–lateral (ML), dorsal–ventral (DV), and anterior–posterior (AP) axes, respectively. Rotation errors were negligible. Software coregistration by translation along the DV and AP axes resulted in consistent agreement between the CT and MR images, without the need for rotation or warping. In vivo coregistered BLT/MRI mouse brain data sets showed a single diffuse region of bioluminescent imaging photon signal and MRI hypointensity. Over time, the transplanted cells formed tumors as histopathologically validated. Disagreement between BLT and MRI tumor location was greatest along the DV axis (1.4 ± 0.2 mm) than along the ML (0.5 ± 0.3 mm) and the AP axes (0.6 mm) because of the uncertainty of the depth of origin of the BLT signal. Combining the high spatial anatomical information of MRI with the cell viability/proliferation data from BLT should facilitate preclinical evaluation of novel therapeutic candidate stem cells.

Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

An idealized biomechanical model. The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001). In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage. N/A.

Effect of air volume fraction and void size on the performance of acoustically thin underwater noise isolation panels

We present experimental measurements of the acoustic behavior of underwater sound absorbing and isolating panels composed of three deeply sub-wavelength layers. The panels were constructed with an inner layer of Delrin plastic containing through-thickness circular air-filled holes sandwiched between two rubber layers. Panel isolation efficacy was quanitifed by measuring insertion loss for non-dimensional panel thicknesses, kd, ranging from 7.2 x 10-3 to 8.5 x 10-2. Finite element numerical simulations will be discussed which indicate that the panel structure mimics a planar encapsulated bubble screen exactly one bubble thick but displays measured performance that is significantly more broadband. Experimental and numerical results indicate that panels with kd ranging from 2.8 x 10-2 to 7.2 x 10-2 can generate a frequency-averaged insertion loss ranging from 5 to 12 dB, dependent on air volume fraction in the panel. The effect of individual air pocket resonance frequency on insertion loss will also be discussed. [Work supported by ONR.]

Measurement of breast tissue composition with dual energy cone‐beam computed tomography: A postmortem study

To investigate the feasibility of a three-material compositional measurement of water, lipid, and protein content of breast tissue with dual kVp cone-beam computed tomography (CT) for diagnostic purposes. Simulations were performed on a flat panel-based computed tomography system with a dual kVp technique in order to guide the selection of experimental acquisition parameters. The expected errors induced by using the proposed calibration materials were also estimated by simulation. Twenty pairs of postmortem breast samples were imaged with a flat-panel based dual kVp cone-beam CT system, followed by image-based material decomposition using calibration data obtained from a three-material phantom consisting of water, vegetable oil, and polyoxymethylene plastic. The tissue samples were then chemically decomposed into their respective water, lipid, and protein contents after imaging to allow direct comparison with data from dual energy decomposition. Guided by results from simulation, the beam energies for the dual kVp cone-beam CT system were selected to be 50 and 120 kVp with the mean glandular dose divided equally between each exposure. The simulation also suggested that the use of polyoxymethylene as the calibration material for the measurement of pure protein may introduce an error of -11.0%. However, the tissue decomposition experiments, which employed a calibration phantom made out of water, oil, and polyoxymethylene, exhibited strong correlation with data from the chemical analysis. The average root-mean-square percentage error for water, lipid, and protein contents was 3.58% as compared with chemical analysis. The results of this study suggest that the water, lipid, and protein contents can be accurately measured using dual kVp cone-beam CT. The tissue compositional information may improve the sensitivity and specificity for breast cancer diagnosis.

Designing and building transducers for use in a molecular acoustics experiment

This work describes the design, construction, and testing of two capacitance transducers for use in a larger project investigating the molecular absorption of sound in certain gases. The transducers are based on designs presented in the literature, modified to work optimally in our system which consists of 4-inch diameter steel pipe. The experiments will be conducted at atmospheric pressure, eliminating design constraints involved when using high pressure gas. However, work done by Bass &amp; Shields shows that to work in these experiments at atmospheric pressure, transducers must have a frequency range of 1 kHz - 100 kHz. [J. Acoust. Soc. Am. Vol 62, p. 346-353, 1977] The basic concept of our transducer depends upon creating a parallel plate capacitor from metal that is flexible enough to move when a sound wave hits it. Our design utilizes 0.051 mm thickness alumninized Mylar film tensioned with a brass retaining ring over a brass backing plate with both secured to a Delrin plastic base for its electrically insulating properties. We will report on the transducer’s frequency response characteristics and initial testing in a send/receive configuration in a sound absorption experiment.

Breast composition measurement with a cadmium-zinc-telluride based spectral computed tomography system

To investigate the feasibility of breast tissue composition in terms of water, lipid, and protein with a cadmium-zinc-telluride (CZT) based computed tomography (CT) system to help better characterize suspicious lesions. Simulations and experimental studies were performed using a spectral CT system equipped with a CZT-based photon-counting detector with energy resolution. Simulations of the figure-of-merit (FOM), the signal-to-noise ratio (SNR) of the dual energy image with respect to the square root of mean glandular dose (MGD), were performed to find the optimal configuration of the experimental acquisition parameters. A calibration phantom 3.175 cm in diameter was constructed from polyoxymethylene plastic with cylindrical holes that were filled with water and oil. Similarly, sized samples of pure adipose and pure lean bovine tissues were used for the three-material decomposition. Tissue composition results computed from the images were compared to the chemical analysis data of the tissue samples. The beam energy was selected to be 100 kVp with a splitting energy of 40 keV. The tissue samples were successfully decomposed into water, lipid, and protein contents. The RMS error of the volumetric percentage for the three-material decomposition, as compared to data from the chemical analysis, was estimated to be approximately 5.7%. The results of this study suggest that the CZT-based photon-counting detector may be employed in the CT system to quantify the water, lipid, and protein mass densities in tissue with a relatively good agreement.

TU‐G‐110‐08: Feasibility of Tissue Composition Measurement with Dual Energy Computed Tomography

Purpose: To investigate the feasibility of tissue composition measurement with dual energy computed tomography as compositional information may help to better characterize suspicious lesions. Method and Materials: Simulations and experimental studies were performed for a flat panel dual energy dual kVp CT system. Simulations were performed to identify optimal beam energy combinations. A figure of merit (FOM) was used to determine the optimal dual energy signal to noise ratio with respect to mean glandular dose. Beam energies ranging from 40 to 140 kVp were simulated in 1 kVp increments. The distribution of dose between low and high energy images was simulated at intervals of 10%. An experimental calibration phantom of 3.175 cm in diameter was constructed from a polyoxymethylene plastic with cylindrical holes filled with water and oil. Similar size samples of pure adipose and lean bovine tissues were also prepared. The phantom and tissue samples were imaged with the dual energy CT system. The calibration phantom was used to estimate the water, lipid and protein contents of each tissue sample. Tissue composition results computed from images were compared to data from chemical analysis of prior tissue samples. Results: The predicted spectra from simulation which optimized the FOM were at beam energies of 40 kVp and 140 kVp with the mean glandular dose divided equally between each exposure. Given tube loading and system constraints, experimental beam energies for the dual kVp CT system were selected to be 50 kVp and 120 kVp. The percentage RMS errors of water, lipid and protein contents as compared to data from chemical analysis were 10.9% for the dual kVp technique. Conclusion: The results of this study suggest that the water, lipid, and protein content may be measured with dual energy CT with relatively good agreement. This might potentially be useful for characterizing suspicious lesions.

TU-A-301-04: Breast Composition Measurement with a Cadmium-Zinc-Telluride (CZT) Based Spectral Computed Tomography System

Purpose: To investigate the feasibility of breast tissue composition in terms of water, lipid and protein with a Cadmium‐Zinc‐Telluride (CZT) based computed tomographysystem, as that information may help to better characterize suspicious lesions. Methods: Simulations and experimental studies were performed with a spectral CTsystem equipped with a CZT‐ based photon countingdetector with energy resolution. Simulations of the figure‐of‐merit (FOM), which represents the signal‐to‐noise ratio (SNR) of the dual energy image with respect to mean glandular dose, were performed to find the optimal configuration of experimental acquisition parameters. A calibration phantom of 3.175 cm in diameter was constructed from a polyoxymethylene plastic with cylindrical holes and filled with water and oil. Similar size samples of pure adipose and lean bovine tissue were used for the three‐material decomposition. Tissue composition results computed from the images were compared to data from chemical analysis of prior tissue samples. Results: The beam energy was selected to be 100 kVp with a threshold energy of 40 keV. The tissue samples were successfully decomposed into water, lipid and protein contents. The RMS percentage errors of the mass density for the three‐material decomposition, as compared to data from chemical analysis, were estimated to be approximately 6.92%. Conclusion: The results of this study suggest that the CZT‐based photon countingdetector may be employed in the CTsystem to quantify the water, lipid, and protein mass densities in tissue with relatively good agreement.

MR thermometry characterization of a hyperthermia ultrasound array designed using the k-space computational method

BackgroundUltrasound induced hyperthermia is a useful adjuvant to radiation therapy in the treatment of prostate cancer. A uniform thermal dose (43°C for 30 minutes) is required within the targeted cancerous volume for effective therapy. This requires specific ultrasound phased array design and appropriate thermometry method. Inhomogeneous, acoustical, three-dimensional (3D) prostate models and economical computational methods provide necessary tools to predict the appropriate shape of hyperthermia phased arrays for better focusing. This research utilizes the k-space computational method and a 3D human prostate model to design an intracavitary ultrasound probe for hyperthermia treatment of prostate cancer. Evaluation of the probe includes ex vivo and in vivo controlled hyperthermia experiments using the noninvasive magnetic resonance imaging (MRI) thermometry.MethodsA 3D acoustical prostate model was created using photographic data from the Visible Human Project®. The k-space computational method was used on this coarse grid and inhomogeneous tissue model to simulate the steady state pressure wavefield of the designed phased array using the linear acoustic wave equation. To ensure the uniformity and spread of the pressure in the length of the array, and the focusing capability in the width of the array, the equally-sized elements of the 4 × 20 elements phased array were 1 × 14 mm. A probe was constructed according to the design in simulation using lead zerconate titanate (PZT-8) ceramic and a Delrin® plastic housing. Noninvasive MRI thermometry and a switching feedback controller were used to accomplish ex vivo and in vivo hyperthermia evaluations of the probe.ResultsBoth exposimetry and k-space simulation results demonstrated acceptable agreement within 9%. With a desired temperature plateau of 43.0°C, ex vivo and in vivo controlled hyperthermia experiments showed that the MRI temperature at the steady state was 42.9 ± 0.38°C and 43.1 ± 0.80°C, respectively, for 20 minutes of heating.ConclusionUnlike conventional computational methods, the k-space method provides a powerful tool to predict pressure wavefield in large scale, 3D, inhomogeneous and coarse grid tissue models. Noninvasive MRI thermometry supports the efficacy of this probe and the feedback controller in an in vivo hyperthermia treatment of canine prostate.

Performance of polyoxymethylene plastic (POM) as a component of a tissue engineering bioreactor

Polyoxymethylene (POM, acetal homopolymer, polyacetal), commercialized as Delrin by DuPont, is an engineering resin with mechanical properties that make it useful for the prototyping and manufacture of laboratory apparatus. These properties include excellent, "metal-like," machining characteristics and dimensional stability, as well as thermal stability, which allows steam sterilization. Historically, POM has been used widely, including as a surgical implant material. For these reasons, we have used this plastic as a media-wetted component in a tissue-engineering bioreactor, with good results. However, a study by LaIuppa et al.5 suggested that POM is unsuitable for use in a cell culture environment (LaIuppa et al. J Biomed Mater Res 1997;36:347-359). POM is based on the polymerization of formaldehyde, and, in addition, contains stabilizers and/or fillers. All of these could potentially be released into the medium, e.g., as formaldehyde or other thermal breakdown products, especially upon repeated autoclaving. The cited report thus appeared plausible, although contrary to our observations. In this study, we specifically assessed whether media conditioned by long-term exposure to machined white POM had a negative effect on the proliferation and chondrogenic differentiation of human mesenchymal stem cells (MSCs). We selected this cell system, as cartilage tissue engineering is the primary application of our bioreactor system. The POM samples were steam-autoclaved 1 to 20 times, to assess the possibility of any toxic thermal breakdown product release into the media. We found that MSCs did not attach directly to machined POM. Because cells that escape from the tissue construct cannot colonize the reactor and compete for nutrients, this is a desirable characteristic of a material used in a tissue-engineering bioreactor. Furthermore, the use of POM-conditioned media had no detectable impact on the proliferation rate of MSCs measured over a one-week period; nor was any effect on chondrogenic differentiation observed at up to 3 weeks in culture. In summary, the use of POM as a culture medium-wetted component appears to be innocuous, at least for human MSCs. The contrast of these findings to those of LaIuppa et al.5 may reflect a cell-type specific sensitivity, or may be due to different handling of the material.

Development of a multichannel fiber-to-fiber optical connector for the D0 upgrade tracker

A tracking detector using scintillating fibers is being developed for the D0 collaboration at Fermilab. The scintillating fibers will be coupled to clear fibers that will transport light to the photodetectors. We have developed connectors which couple the two types of fibers. The first 128-channel prototypes were machined using Delrin plastic to have v-shaped grooves. Fibers were glued into the grooves and their ends were finished with diamond fly-cut tools. Mating connectors were optically coupled by optical grease. Using a green light-emitting diode and a silicon photodiode, we measured average light transmission between 97% and 99%. Later versions of the v-groove connectors were made of acrylonitrile-butadiene-styrene plastic by injection molding.

Laboratory Study of Water Coning In a Layered Model

Abstract Experimental and numerical studies were made of water coning under twophase, immiscible. incompressible flow. A pie-shaped cylindrical sand pack having radial symmetry was the model. Saturations were measured in situ by 70 micro-resistivity probes embedded in the sand pack. Two models have been used; a homogeneous one and one which contained two horizontal, low-permeability layers, giving a 50: 1 permeability ratio with the bulk of the matrix. In the layered system studied, it was found that at the same pore volume of injection oil recovery decreased for higher oil viscosity or higher production rate. Stratification aggravated coning. A 10%-pore-volume bank of polymer solution injected at the oil-water contact delayed water breakthrough, but caused the drive water to viscous finger. Introduction Previous papers (1,2) have described results of numerical coning studies, a literature review on coning, and the effect f various parameters on the formation and behaviour of the water cone. The results indicated that the numerical model adequately simulated the experiment. The present paper deals with experimental and numerical studies which were carried out in a layered coning model. Four experiments were conducted: three of the experiments dealt with the effect of oil viscosity and production rate on the behaviour of the cone; a fourth involved the injection of a 10%-pore-volume polymer slug at the oil-water contact before water injection. Experimental Model For the experimental study, a pie-shaped, cylindrical coning model was constructed of Delrin plastic. The model was 40 cm high and had a radius of 50cm and an angle of 30 degrees. It was constructed of 5-cm-thick Delrin and was supported by a metal frame all around to avoid bulging during flow. To distribute the injected water uniformly across the bottom face of the sand pack; the bottom plate had fluid grooves that were overlain by several layers of 325-mesh monel screen. Seventy micro-resistivity probes were constructed and positioned inside the model for measuring the electrical resistivity. The resistivity probes were 316 SS wires and no screens were used at the measurement points. In this way, corrosion was eliminated and distortion of fluid flow was minimized. A thin, insulated wire led from each screen through a hole drilled in the side plates of the model to an electrical 70-poim junction box, and from there to a specially constructed 70-channel scanner. The scanner could scan any or all of the resistivity probes at a rate ranging from 1/2 to 60 seconds per probe. A timer permitted continuous scanning or time-lapse scanning ranging from once per hour to once every 8 hours. The output of the scanner was put through a digital voltmeter to a digital recorder. During a flow experiment, the resistivity at each probe thus could be measured and recorded automatically. The resistivity probes were positioned on a central symmetry plane, thus permitting measurements far from the boundaries of the model. Coordinates or probes in the z direction (measured positive downward) were 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 and 35.0 cm.

Paper 23: A Theoretical and Experimental Investigation of the Effect of Elastic Distortions on the Performance of Journal Bearings

This paper describes details of a solution to the finite journal bearing problem, including the effects of elastic distortions in the bearing liner. Solutions for the particular case of a bearing of length to diameter ratio of 1, outside to inside diameter ratio of 1·3, and Poisson's ratio of 0·4 have been obtained and the results are compared with experimental results obtained with a Delrin plastic bearing. Good agreement between theory and experiment has been obtained. The theory, which is applicable to soft shell bearings supported in a rigid housing, predicts that: (1) the ratio of the peak pressure to the average pressure is reduced; (2) the bearing stiffness is reduced; (3) the minimum film thickness for a given load is reduced by elastic distortions at eccentricity ratios less than unity; and (4) the friction is reduced.