Procedia Engineering 150 ( 2016 ) 1227 – 1232

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1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer-review under responsibility of the organizing committee of ICIE 2016doi: 10.1016/j.proeng.2016.07.122

ScienceDirect

International Conference on Industrial Engineering, ICIE 2016

Car Windshield Protection

A.S. Pereverzev*, B.A. Semenikhin South-west State University, 50 years of October Str., 305040, Kursk, Russia

Abstract

Research findings and design have allowed to develop a perspective way of the car anti-cracker shield protection, which is the application of the protective pad mounted across the perimeter of the car windscreen and protecting the most vulnerable sections of the windshield from chips and cracks (glass fixing seats in the back of the car). In the course of work the need for development of a way of the car anti-cracker shield protection is justified, the required investigation and the calculation are carried out and the size of the protective pad for a particular car model is determined. © 2016 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the organizing committee of ICIE 2016.

Keywords: Windshield; strength; stress

1. Introduction

Nowadays, the windshield is an integral part of the vehicle structure. Due to its design and location, the windshield is exposed to a wide variety of loads: wind load, load due to the elastic deformation of the car body, as well as the impact load by roadside stones. As a result, the windscreen chips and cracks, which negatively affect visibility and safety, appear [1].

Moreover, defect repair is generally expensive, especially when it comes to crack repair. The use of protective films can significantly reduce the probability of crack and chips formation in the windshield, but their cost and installation are quite expensive too [2, 3]. Therefore, the significance of the work is determined by the need for the safe vehicle operation, as well as the need for development of alternative ways to protect the windshield from cracking in order to prolong its life. The main objectives of the work are to study strength characteristics of glass and to design a method to protect the windshield from cracking.

* Corresponding author. Tel.: 89513303875.

E-mail address: Chaser-93@yandex.ru

© 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer-review under responsibility of the organizing committee of ICIE 2016

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2. The study of strength characteristics of glass

As a rule, the windshield is susceptible to getting cracks irregularly. From a scientific point of view, this can be justified as follows. The windshield is a plate rigidly mounted on the vehicle body’s perimeter [4, 5]. When the windshield is exposed to shock loading, it buckles in the affected area, consequently, a wide variety of stress appears.

The compressive strength of glass is extremely high, but its tensile and flexural strength are significantly lower. Accordingly, the factor determining generation of a crack in the fixing zone is the bending stress, which is not constant for glass, as it is for many other materials, but varies depending on the following reasons:

duration of load; schemes of a window supporting: along the contour from 4 or 2 (3) sides; stiffness of a window fixing on the support; the ratio of length to width of a window [6]. Since the windshield is rigidly fixed on all sides in the vehicle, the bending stress in the glass fixation positions

will be much higher than in its center. It is the excess of the allowable stress that leads to the formation of cracks in the glass fixation positions in the vehicle body, where its excess is most likely to happen due to the construction [8, 9].

3. Developing a method of protecting the windscreen from cracking

Taking into consideration the aforementioned disadvantages of windshield protection films, main reasons of formation of chips and cracks on the windshield and discovered windshield weakest areas we have developed a new way to protect the car windshield, which is the application of the protective pad [10, 11]. The design of the protective pad is shown in Fig. 1.

Fig. 1. A protective windshield pad.

The engineered protective pad is made as a closed transparent strip, that locates on the perimeter of the windshield and consists of a wedge-shaped transparent elastic outer layer and an adhesive inner layer.

The protective pad works as follows. With a help of an adhesive layer the blunt edge of the wedge-shaped profile of the paste is glued to the outer surface of the windshield along its perimeter to in the windshield fixing position in the vehicle body, and the sharp edge is glued to in the direction to the window center. If a foreign body contact with the windshield fixation zone, a thicker layer of the elastic material damps the impact energy and thus prevents the windshield from cracks. The further reduction of the thickness of the protective pad’s elastic layer toward the glass center and, accordingly, the degradation of its absorption performance are offset by the improved elastic properties of the windshield in the direction to its center.

This design of the pad helps to protect the glass fixation zones in the vehicle from cracks, as already mentioned, these zones are most susceptible to cracking. In addition, the designed construction, unlike protective films, eliminates the need for a protective coating over the entire surface of the windscreen and that is beneficial to the useful life of a protective pad [12, 13].

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Due to the small width of the pad, car owners will be able to save money by gluing the pad to a windshield on their own.

4. Modeling of the protective pad and determination its size

A calculation and design of the protective pad were made for the windshield of Lada-2110 by means of Ansys software, which allows to model the car windshield and the conditions of its operation, and also identify the maximum stress that appears due to the impact force on the various sections of the windshield [14]. Diagrams of maximum stress are shown in Fig. 2.

Fig. 2. (a) The diagram of the maximum stress under the impact force in the upper fixation positions; (b) The diagram of the maximum stress under the impact force on the bottom corner of fixation positions; ( ) The diagram of the maximum stress under the impact force in a side area of fixation positions; (d) The diagram of the maximum stress under the impact force in the top corner of fixation positions; (e) The diagram of the

maximum stress under the impact force in the lower fixation positions; (f) The diagram of the maximum stress under the impact force in the center of the glass.

According to a calculation of the program shown in Table 1, application of the same load to the different parts of a car windshield reveals that the most vulnerable ones are, as was mentioned before, the glass fixation positions [15].

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Table 1. The software calculation results

The direction of load application

Values of the maximum stress, MPa, depending on the distance from the edge of the glass, mm

10 30 50 70 90 110 130 150 170 190 bottom - center 6,3 11,5 11,7 12,8 13,4 11,9 9,6 7,8 6,4 5,5 up - center 6,9 12,5 15 13,8 11,8 9,6 7,8 6,5 5,3 5,1 side - center 4,4 11,9 15,1 14,8 12,6 10,5 8,5 6,4 5,5 5,2 bottom corner - center 12,2 19,2 14,2 8,6 7,5 7,1 6,6 6,2 5,7 5,3 top corner - center 7,1 12,4 10,3 9,5 9,2 8,6 7,9 6,8 6,1 5,7

Dependency graphs for the stress and the position and direction of load application are shown in Fig. 3. The

graph shows that peak values of the maximum stress in the fixation positions were observed under the impact at distances of 30 - 90 mm from the edge of the glass. This heterogeneity can be explain by the geometry of the windshield design [16].

Fig. 3. (a) Dependency graph for the maximum stress and load application place in the direction from the bottom edge to the center; () Dependency graph for the maximum stress and load application place in the direction from top edge to center; (c) ) Dependency graph for the

maximum stress and load application place in the direction from the side edge to the center; (d) ) Dependency graph for the maximum stress and load application place in the direction from the bottom corner to the center; (e) ) Dependency graph for the maximum stress and load application

place in the direction from the top corner to the center.

A calculation was made for the optimum thickness of the elastic layer according to the maximum stress (19.2 MPa at the lower side of fixation positions), and in other parts of the protective pad, due to constancy of the thickness of the wedge-shaped profile, the safety margin formed at a distance of 30 mm from the edge of the glass.

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Experiments have shown that, using the protective pad from the PET material as an elastic material, the required thickness of the elastic layer in zones where the peak maximum stress appears will be 1 mm [17]. The dependence is shown in Fig. 4.

Fig. 4. Dependency graph for the stress and the thickness of the elastic layer of the protective pad.

The graph shows that when the thickness of the elastic layer is 1 mm, the desired value of the maximum stress of 5.2 MPa can be achieved [18].

According to the distribution of the maximum stress, the optimum width would be a distance from the edge of the glass if the stress overcomes its peak and reach safe values: 130 mm from the upper and lower edges and 130 mm from the left and right edges. Taking into account the width of the protective pad and the required thickness of the elastic layer, a wedge-shaped profile of the protective pad will have the dimensions shown in Fig. 5.

Fig. 5. Dimensions of the profile of the protective pad for the fixation positions

On grounds of the performed calculations, the modeled protective pad for the windshield of Lada-2110 will have the form shown in Fig. 6 [19, 20].

Fig. 6. The protective pad for the windshield of Lada-2110.

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4. Conclusion

The research findings and design have allowed to identify the most vulnerable areas of the windshield. These are the glass fixation positions in the vehicle body .

By means of Ansys software, a windshield of a particular car was modeled, soft spots of its fixation in the vehicle body were revealed and appropriate manufacturing materials were selected. All this made possible the determination of the size of the protective pad.

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