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Two analytical tools for failure predictions in free-expansion tube hydroforming, namely “Process Window Diagram” (PWD) and forming limit curve (FLC), are discussed in this paper. The PWD represents the incipient failure conditions of buckling, wrinkling and bursting of free-expansion tube hydroforming processes in the plane of process parameters, e.g. internal pressure versus axial compression. The PWD is a useful tool for design engineers to quickly assess part producibility and process design for tube hydroforming. An attempt is also made to draw the differences between FLCs for sheet and tube so that the appropriate FLC could be used to estimate the bursting or fracture limits in free-expansion tube hydroforming processes.

An axisymmetric finite element model is generated to simulate the windshield glass damage propagation subjected to impact loading of a flying object. The windshield glass consists of two glass outer layers laminated by a thin poly-vinyl butyral (PVB) layer. The constitutive behavior of the glass layers is simulated using brittle damage mechanics model with linear damage evolution. The PVB layer is modeled with linear viscoelastic solid. The model is used to predict and examine through-thickness damage evolution patterns on different glass surfaces and cracking patterns for different windshield designs such as variations in thickness and curvatures.

This paper describes a method for predicting structural failure probabilities for automotive windshields. The predictive model is supported by the data from strength tests performed on specimens of automotive glass. Evaluations of stresses can be based on finite element calculations, or measurements of the residual stresses that arise from fabrication. Failure probabilities for each subregion of a windshield are estimated from the local state of stress, the surface area or length (for edge elements) of the subregion, and statistical distributions of glass strengths. Example calculations are presented that show the relative contributions of edge stresses, surface stresses and residual stresses to calculated failure probabilities.

A finite element model of a lightweight vehicle body-in-white has been developed to study the contribution of a lightweight vehicle's glazing system to its overall structural rigidity. This paper examines the effect of the glazing thickness and glazing molding stiffness on the glazing system contribution to a lightweight vehicle's torsional rigidity. The individual stiffness contributions of the front and back glazing were determined, as well as the weight of the glazing as a function of its thickness. In the first set of analyses detailed in this paper, the torsional and bending loadcase was investigated by comparing the baseline model to a no-glass model. It was shown that the glazing system contributes significantly to the overall structural rigidity of the auto-body. The difference was mainly in the torsional rigidity which was 12.4% more rigid than the no-glass model. The bending rigidity was only increased by 0.5% in the glazing model.

This paper presents the strength data for conventional automotive windshields in both the new and used conditions. More specifically, the biaxial strength of outer surface of curved and symmetrically laminated windshield, measured in biaxial flexure, is reported. The relative contributions of inplane membrane stress, which can be significant for new windshields, and bending stress are quantified with the aid of strain gauge rosettes mounted on both the outer and inner surfaces of windshield. The strength distribution for new and used windshields, based on Weibull distribution function, is found to be multimodal indicating more than one family of surface flaws. Depending on handling damage during manufacturing, assembly and installation processes, the low strength region of new windshields can approach that of used windshields with 50,000+ road miles!

Temporal light modulation (TLM), colloquially known as “flicker,” is an issue in almost all lighting applications, due to widespread adoption of LED and OLED sources and their driving electronics. A subset of LED/OLED lighting systems delivers problematic TLM, often in specific types of residential, commercial, outdoor, and vehicular lighting. Dashboard displays, touchscreens, marker lights, taillights, daytime running lights (DRL), interior lighting, etc. frequently use pulse width modulation (PWM) circuits to achieve different luminances for different times of day and users’ visual adaptation levels. The resulting TLM waveforms and viewing conditions can result in distraction and disorientation, nausea, cognitive effects, and serious health consequences in some populations, occurring with or without the driver, passenger, or pedestrian consciously “seeing” the flicker.