Quantifying the Visibility of Surface Distortions in Class “A” Automotive Exterior Body Panels

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
K. D. Fernholz
Keyword(s):  
Automotive Industry ◽  
Human Perception ◽  
Element Model ◽  
Subjective Assessment ◽  
Model Data ◽  
Surface Appearance ◽  
Class A ◽  
Surface Distortion ◽  
Subjective Assessments ◽  
Surface Distortions

Visible distortions in Class “A” automotive surfaces are unacceptable to vehicle customers and therefore are considered to be cosmetic defects. The automotive industry currently relies upon subjective assessment of the severity of these distortions to determine whether a component's surface appearance is acceptable. Given the inherent variability in subjective assessments, however, an objective measurement for assessing the severity of defects would be of great benefit to the industry. The issues that need to be addressed to objectively quantify the severity of one particular type of surface distortion are discussed and a methodology for quantifying the severity of that surface distortion in a way that correlates to human perception is proposed. Experimental and finite element model data supporting the proposed methodology is presented.

Design of a Stamping Test for Investigating Surface Distortion in Sheet Metal Parts

2008 ◽  
Author(s):  
Zhengchun Fu ◽  
Ping Hu ◽  
Hui-Ping Wang ◽  
Kunmin Zhao
Keyword(s):  
Sheet Metal ◽  
Measurement Techniques ◽  
Geometric Parameters ◽  
Time Dynamic ◽  
Sheet Metal Parts ◽  
Root Cause ◽  
Class A ◽  
Surface Distortion ◽  
Metal Stamping ◽  
Surface Distortions

Surface distortions/deflections are frequently introduced into the Class “A” surfaces during sheet metal stamping processes. However, the origins of the draw die related surface distortion/deflection have not been well understood. This paper presents our design of a stamping test for the investigation of the distortion phenomenon. Five geometric parameters are first identified to represent basic geometry of typical automobile outer panel depression features around the surface distortions. Experimental stamping dies are then designed to reflect various combinations of these five geometric parameters with the assistance of numerical simulations to ensure that the designed dies are able to replicate the surface distortion phenomenon. Also, real-time dynamic measurement techniques are designed to collect historical data of strains and deflection on the stamping panels. Our preliminary tryouts show that the designed stamping test successfully replicates the distortion phenomenon observed in production stamping processes. It provides a platform for the investigation of the root-cause of the draw die related surface distortions.

Imaging correlates of successful endoscopic third ventriculostomy

2000 ◽  
Vol 92 (6) ◽  
pp. 915-919 ◽  
Author(s):  
Abhaya V. Kulkarni ◽  
James M. Drake ◽  
Derek C. Armstrong ◽  
Peter B. Dirks
Keyword(s):  
Clinical Success ◽  
Subjective Assessment ◽  
Third Ventriculostomy ◽  
Ventricular Size ◽  
Content Type ◽  
Exact Test ◽  
Subjective Assessments ◽  
Flow Void ◽  
Fine Print

Object. The goal of this study was to determine and compare imaging correlates in pediatric patients who underwent successful or failed endoscopic third ventriculostomies (ETVs). To this end, the authors measured ventricular size changes and the presence of cerebrospinal fluid (CSF) flow void in both groups of children following ETV.Methods. Images obtained in children with hydrocephalus immediately before and at least 30 days after having undergone ETV were reviewed by four independent observers (two blinded and two nonblinded). Each observer independently measured the frontal and occipital horn ratio ([FOR], a reliable and valid measure of ventricular size) and provided a subjective assessment of the presence of a flow void at the ETV site, the degree of periventricular edema, and the amount of CSF over the cerebral hemispheres.There were 29 children whose mean age was 6.6 years at the time of ETV and who had a mean postoperative follow-up period lasting 1.6 years. Postoperatively, the mean reduction in ventricular size (as measured using the FOR) was 7% (95% confidence interval [CI] 3–11%) in cases that were deemed failures (eight patients) and 16% (95% CI 12–20%) in clinically successful cases (21 patients). This reduction was significantly greater in cases of clinical success compared with those that were deemed failures (p = 0.03, t-test). There were no substantial differences between blinded and nonblinded assessments. Flow void was present in 94% of successes and absent in 75% of failures (p = 0.01, Fisher's exact test). The other subjective assessments were not significantly different between the groups of successes and failures.Conclusions. Ventricular size appears to be somewhat reduced in both groups of patients who underwent clinically successful and failed ETV; however, the reduction is significantly greater among clinically successful cases. The presence of a flow void also appears to correlate with clinical success and its absence with clinical failure.

scholarly journals Analysing Random Vibration of KLT Box during Transporting by Finite Element Method

10.29007/b1th ◽  
2022 ◽  
Author(s):  
Cong Hoa Vu ◽  
Ngoc Thien Ban Dang
Keyword(s):  
Finite Element ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Automotive Industry ◽  
Random Vibration ◽  
Element Model ◽  
Vibration Testing ◽  
Time Data ◽  
Power Spectral ◽  
The Impact

Today, freight is an extremely important industry for the world we are living. Fast transportation, large volume...will optimize the cost, time and effort. Besides, ensuring the products safety is a matter of concern. During transporting, it is inevitable that the vibration caused by the engine, rough road surface...the cargo inside can be damaged. Automobile industries have prime importance to vibration testing. Sine vibration testing is performed when we have been given with only one frequency at given time instant. Trend to perform random vibration testing has been increased in recent times. As random vibration considers all excited frequencies in defined spectrum at known interval of time, it gives real-time data of vibration severities. The vibration severity is expressed in terms of Power Spectral Density (PSD). KLT box is an industrial stacking container conforming to the VDA 4500 standard that was defined by German Association of the Automotive Industry (VDA) for the automotive industry. The aim of this paper is study about random vibration and power spectral density analysis, how it can be used to predict the impact of hash road to the KLT box on container / truck during transportation. Finite element model is developed in ANSYS, modal analysis and random vibration analysis were done.

Application of a FRF Based Model Updating Technique for the Validation of Finite Element Models of Components of the Automotive Industry

1995 ◽  
Author(s):  
Stefan Lammens ◽  
Marc Brughmans ◽  
Jan Leuridan ◽  
Ward Heylen ◽  
Paul Sas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Automotive Industry ◽  
Stiffness Matrix ◽  
Model Updating ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Model Parameters ◽  
Finite Element Models ◽  
Analytical Dynamic

Abstract This paper presents two applications of the RADSER model updating technique (Lammens et al. (1995) and Larsson (1992)). The RADSER technique updates finite element model parameters by solution of a linearised set of equations that optimise the Reduced Analytical Dynamic Stiffness matrix based on Experimental Receptances. The first application deals with the identification of the dynamic characteristics of rubber mounts. The second application validates a coarse finite element model of a subframe of a Volvo 480.

Stress Analysis of a Bulk-filled Class V Light-cured Composite Restoration

1994 ◽  
Vol 73 (8) ◽  
pp. 1470-1477 ◽  
Author(s):  
T.R. Katona ◽  
M.M. Winkler
Keyword(s):  
Finite Element ◽  
Resin Composite ◽  
Critical Factor ◽  
Element Model ◽  
Leakage Loss ◽  
Class V ◽  
Clinical Complications ◽  
Transient Events ◽  
Surface Distortions ◽  
Composite Restoration

Clinical failures are often associated with the polymerization shrinkage of resin composite restorative materials. These problems include tooth sensitivity and fracture, marginal leakage, loss of the restoration, and recurrent decay. Our goal was to examine transient composite distortions and interface stresses as a bulk-filled light-cured composite polymerized in a Class V restoration. The analysis was based on a finite element model. The curing of the restoration was divided into 4 steps: approximately 1/30, 1/4, 1/2, and full depth (1/1) of cure. Since the actual curing pattern is not known, calculations were performed for three hypothetical (flat, convex, and concave) polymerization front shapes. The calculations showed that the assumed shape was a critical factor in determining cured surface deformations. For example, the initial cure depth (1/30) resulted in a surface bulge if the polymerization front was presumed convex, while the concave front resulted in a large intrusion. By the time that about 1/2 the depth of the restoration was cured, the differences were essentially gone. The final surface outline was intruded. Interface stresses in the curing restoration were qualitatively similar regardless of the assumed polymerization shape. As with surface distortions, the stresses changed with curing depth. It was concluded that (1) transient events during polymerization are possible contributors to clinical complications, and (2) more must be known about the polymerization pattern.

Investigation and Correction of Surface Distortion in Dies With Typical Depression Features

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Hui-Ping Wang ◽  
Kunmin Zhao ◽  
Ping Hu ◽  
Zhengchun Fu ◽  
Jing-Ru Bao
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Historical Data ◽  
Time Measurement ◽  
Geometric Parameters ◽  
Class A ◽  
Real Time Measurement ◽  
Surface Distortions ◽  
Full Factorial

Surface distortions are frequently introduced into Class “A” surfaces during various sheet metal forming operations such as drawing, trimming, and flanging. The origins of these surface distortions have not been well understood. The scope of this research is to investigate the distortion that occurs in the draw operation and to find effective and practical corrective methods. Five geometric parameters are first identified to represent typical depression features in automobile outer panels. Experimental dies are then designed to reflect various combinations of these five geometric parameters with the assistance of numerical simulations to ensure that the dies can make parts free of major defects such as splits and wrinkles. Surface distortions are observed in our stamping experiments and various techniques are used to measure and record the distortions for further mathematical analysis. Historical data of strains and deflections in distortion areas are collected through real-time measurement. The effects of three geometric parameters on distortion are analyzed using a full factorial DOE model. A geometry morphing program based on UG-NX platform is developed. The program is used to morph the die face in the distortion areas. Finally, three approaches that aim to correct distortions are tried out and the die morphing proves to be a practical and effective method.

The 1-in-X Effect on the Subjective Assessment of Medical Probabilities

2011 ◽  
Vol 31 (5) ◽  
pp. 721-729 ◽  
Author(s):  
Stefania Pighin ◽  
Lucia Savadori ◽  
Elisa Barilli ◽  
Laura Cremonesi ◽  
Maurizio Ferrari ◽  
...  
Keyword(s):  
Risk Communication ◽  
Health Professionals ◽  
Subjective Assessment ◽  
Medical Conditions ◽  
Subjective Assessments ◽  
Visual Aid ◽  
Different Populations ◽  
Intuitive Sense

Among numerical formats available to express probability, ratios are extensively used in risk communication, perhaps because of the health professional’s intuitive sense of their clarity and simplicity. Moreover, health professionals, in the attempt to make the data more meaningful, tend to prefer proportions with a numerator of 1 and shifting denominators (e.g., 1 in 200) rather than equivalent rates of disease per unit of population exposed to the threat (e.g., 5 in 1000). However, in a series of 7 experiments, it is shown that individual subjective assessments of the same probability presented through proportions rather than rates vary significantly. A 1-in- X format (e.g., 1 in 200) is subjectively perceived as bigger and more alarming than an N-in- X* N format (e.g., 5 in 1000). The 1-in- X effect generalizes to different populations, probabilities, and medical conditions. Further-more, the effect is not attenuated by a communicative intervention (verbal analogy), but it disappears with an icon array visual aid.

Influence of Window Views on the Subjective Evaluation of Discomfort Glare

2010 ◽  
Vol 20 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Geun Young Yun ◽  
Ju Young Shin ◽  
Jeong Tai Kim
Keyword(s):  
Control Systems ◽  
Subjective Evaluation ◽  
Subjective Assessment ◽  
Potential Effect ◽  
Psychological Factor ◽  
Future Design ◽  
Subjective Assessments ◽  
Discomfort Glare ◽  
The Difference

A window is an indispensable element in a building and acts as a view-giving component that keeps occupants in touch with the outside. This study investigated the potential effect of different window views on the subjective assessment of discomfort glare from a simulated window that rendered blank, natural and man-made views from far to close distances. Forty-eight subjects (24 men, 24 women) participated in the experiments. The experimental results confirmed that the subjective evaluation of discomfort glare can vary with the type of window views presented. The results also indicated that there were noticeable variations in the subjective assessments of discomfort glare over the same visual stimuli. A preliminary criterion for classification of subjects’ sensitivity to glare was illustrated and the difference for the ‘‘glare-sensitive’’ and ‘‘glareinsensitive’’ people was statistically significant. This study found that the psychological factor such as window views could be an important factor in the subjective evaluation of discomfort glare. Widely used glare evaluation formulas such as unified glare rating and daylight glare index would not consider psychological factors. Thus, the finding from this study would contribute to a more realistic evaluation of discomfort glare for future design of glare control systems.

Subjective Assessment of the Vibration Discomfort Produced by Different Hand Held Machines

1989 ◽  
Vol 8 (2) ◽  
pp. 50-61 ◽  
Author(s):  
M. Broyde ◽  
P. Donati ◽  
J. Bitsch
Keyword(s):  
Human Exposure ◽  
Subjective Assessment ◽  
Paired Comparisons ◽  
Trained Subjects ◽  
Subjective Method ◽  
Subjective Assessments ◽  
Within Subjects ◽  
Electrodynamic Vibrator ◽  
Method Of Paired Comparisons ◽  
Good Agreement

A subjective method of paired comparisons was developed to compare the discomfort caused by the vibration from hand-held power tools with the predictions obtained using the procedures recommended by standards for the evaluation of human exposure to hand-transmitted vibration. Fiteen trained subjects were exposed in the laboratory to seven different vibration exposures produced by five hand-held tools (one of the tools was used in two positions) and an electrodynamic vibrator. The good agreement observed between and within subjects shows that they can reliably rank vibration dicomfort produced by different hand-held tools. For five vibration exposures out of seven, the rank deduced from the subjective assessments was in accord with the rank of the predicted evaluations derived from the frequency-weighted acceleration values measured. An exposure with highly impulsive vibration was rated as being much more annoying than it was foreseen by the current procedures of evaluation. The operator's position proved to be an important factor in the perception of the discomfort.

Validity of Subjective Evaluations for the Assessment of Lip Scarring and Impairment

2002 ◽  
Vol 39 (6) ◽  
pp. 587-596 ◽  
Author(s):  
Kelly Ritter ◽  
Carroll-Ann Trotman ◽  
Ceib Phillips
Keyword(s):  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Subjective Assessment ◽  
Future Research ◽  
Subjective Evaluations ◽  
Subjective Assessments ◽  
Interexaminer Reliability ◽  
School Of Dentistry ◽  
The University ◽  
The Impact

Objective In patients with cleft lip and palate, the aim of the study was (1) to determine and compare the level of agreement among examiners’ subjective evaluations of static and dynamic lip form; (2) assess possible bias of examiners’ subjective evaluations; and (3) determine the impact of lip scarring on an examiner's subjective assessment of dynamic lip form. Setting Patients and subjects were recruited from the University of North Carolina Cleft Lip and Palate Center and School of Dentistry. Patients, Participants Thirteen patients with unilateral cleft lip and palate and varying degrees of cleft scar severity were selected and one subject without cleft who wore artificial scars of varying severity. Interventions For the patients with cleft, a previously repaired complete cleft lip and palate. Photographs and videotape recordings were made of the patients with cleft and the subject without cleft, with and without the artifical scars, at rest and smiling. Main Outcome Measure(s) Rankings of cleft scar severity and impairment on a 6-point Likert scale by a lay and professional panel. Results Intra- and interexaminer reliability was good for the lower facial regions at rest but not during movement. Professionals gave ratings of greater severity and impairment than laypersons, and professionals agreed when rating the lower faces at rest more so than during movement. Lip scarring affected perceptions of impairment during movement by viewers in both panels. Conclusions Subjective assessments can be affected by methodological approaches, professional experience, and stimulus type. Future research should focus on establishing objective methods to evaluate patients with cleft lip and palate at rest and during function.

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