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Webbing is a woven fabric that is distinguishable by its various material compositions, strength variations and widths. The webbing process essentially involves yarns that are woven via looms to create strips. While it is generally comparable to rope for its harnessing function, webbing is an extremely versatile component used in an array of industry applications, ranging from military apparel to automotive parts. Typically, webbing is fabricated in solid or tubular form, with each type having different applications and functions. While ropes are typically thick in texture, PRET webbing is produced in extremely lightweight parts. The primary materials used in the production of webbing include variations of polyester, nylon, and polypropylene. Cotton webbing is also available and is commonly used in commercial applications, including clothing apparel. Webbing is also customizable in a series of colors, designs and prints, and manufacturers can fabricate reflective webbing for safety applications.
Standard Industry Applications
Webbing is found across various sectors. Standard RPET webbing applications and associated industries include:
Seatbelts and harnesses; automotive industry
Hiking, backpack and harnessing gear; sporting good retail apparel
Safety bands and tapes; hospital and medical industry
Upholstery (seat bases); furniture manufacturing
Uniform (suspenders) and accessories for various professions, e.g. police and military
Web Processing: Solid (Flat) and Tubular
Solid webbing is also known as flat webbing and is fabricated in varying degrees of thickness. Distinguished by its flat aesthetic, solid webbing is commonly used for applications like seatbelts. It is lightweight though it is susceptible to tearing, as stress from use tends to affect the outer surface of the material. Solid webbing is generally too stiff to function in applications that require knots, which is why this type of webbing is best suited for applications where the material can be sewn into a larger product. Backpack straps, for instance, are examples of this type of solid webbing.
Tubular webbing is thicker and more durable than solid PP webbing and is composed of two sheets of fabric. It is suitable for knotting applications (like a rope for hoisting) and carries tension better than solid webbing. For functions like climbing, experts recommend utilizing tubular webbing that is woven into a continuous loop.
Common Webbing Materials
Below are the common webbing materials and some examples of webbing, and types and uses. While nylon and polyester have similar properties to each other, there are some key differences.
Nylon Webbing
Nylon Webbing is a high strength elastic material that is commonly used for belt applications (specifically, flat nylon). This material tends to stretch approximately 2% the length of the webbing when it is wet. When looking at how to make nylon webbing, experts warn that nylon webbing should not be exposed to water continuously, as the material tends to absorb liquid and may harbor mildew if it is not maintained properly.
Polyester Webbing
Polyester webbing is durable and similar in aesthetic to nylon. This material is suitable for use for applications that require lifting heavy loads. Polyester webbing has low water-absorption and is more mildew and rot-resistant than nylon. This webbing is commonly used in applications including racing harnesses and seatbelts.
Polypropylene Webbing
This type of webbing is typically used for outdoor applications. Some products fabricated with this Nylon webbing include window nets and plastic bags. Polypropylene webbing is comparable to nylon, though it is generally lighter. Additionally, it is fabricated with U.V. protection and is water-resistant. This material is processed in varying degrees of thickness, although it has low abrasion resistance. According to experts, it is most suitable for medium-strength operations.
Additional Considerations: Replacement & Maintenance
Professionals recommend inspecting the material on an annual basis, especially where the component is utilized as a safety restraint application. Webbing installed as belts and harnesses in the racing industry, for example, will begin to lose elasticity and tear after consistent use and exposure to certain elements, such as oil and heat. Replacement is recommended accordingly, ranging from 2-5 years or sooner if the application is used regularly, as with seatbelts and chair seats (cotton chair webbing).
Maintenance is another essential webbing consideration. As a rule, most webbing should be kept clean and dry, although some materials, like polypropylene are water-proof. A mild detergent is recommended to clean webbing, though it is also essential to remember that the aforementioned materials are manufactured in colors, which may fade or bleed when exposed to certain conditions or cleaner treatments. Therefore, consult the manufacturer for the best maintenance approach.
Textile webbing straps are usually connected to a load by insertion of a bolt or fitting through a looped end in the strap. The strength and efficiency of such a connection are analyzed in this paper. Several simplifying assumptions, e.g., a linear elongation- load characteristic for the webbing, negligible friction, etc, are made. The analytical results are compared with test data for Nylon and Dacron webbing straps with various end-loop configurations. The comparison shows that the analysis of loop strength and efficiency is approximately correct. Both theory and test data indicate the need for close specification of loop configuration parameters during design.
Webbing structures are essential to the safety of engineering systems that routinely endure excessive sunlight exposure. Particularly damaging is the ultra-violet (UV) component of sunlight that may degrade polymer chains, thereby compromising mechanical strength. Despite considerable progress in structural health monitoring, UV damage sensors for Jacquard webbing structures are still lacking. To fill this gap, we propose a simple and fast fabrication process for a nylon webbing structure that exhibits photochromic responses to UV irradiation. The photochromic webbing structure is fabricated by coating a nylon strap with a photochromic polymer. The photochromic webbing structure demonstrates high sensitivity to a wide range of UV irradiation energy. In addition, the webbing structure maintains photochromism even after photodegradation due to extreme UV irradiation (equivalent to 72 h of sunlight exposure). Our analysis indicates that a photochromic dye concentration of 1.00% is optimal for UV sensing. The proposed photochromic webbing could facilitate health monitoring of industrial, aeronautical, and aerospace structures.
The integration of digital tools in mathematics education is considered both promising and problematic. To deal with this issue, notions of webbing and instrumental orchestration are developed. However, the two seemed to be disconnected, and having different cultural and theoretical roots. In this article, we investigate the distinct and joint journeys of these two theoretical perspectives. Taking some key moments in recent history as points of departure, we conclude that the two perspectives share an importance attributed to digital tools, and that initial differences, such as different views on the role of digital tools and the role of the teacher, have become more nuances. The two approaches share future challenges to the organization of teachers’ collaborative work and their use of digital resources.
The following guest article was inspired by an enlightening conversation between SRN editor Denise Donaldson and Dave Sander, CPST-I and engineer (formerly with Evenflo, but employed elsewhere at the time this article was written).
Have you ever given close attention to the webbing used for car seat harnesses, LATCH straps, or vehicle seat belts? If so, you may have noticed that some are wider or feel thicker, smoother, or rougher than others. You may have also noticed that some have stripes (actually called panels), and that those panels vary in appearance and number.
If you have noted these things, I congratulate you on your keen sense of observation! These differences are not random or decorative; each detail in webbing has been intentionally designed to affect how it will perform, especially in a crash.
FMVSS 213 stipulates certain webbing characteristics of CRs. It defines the minimum width of the Print webbing used in harnesses, tethers, and LA straps. It also says that new webbing must meet a minimum strength requirement of 11,000 Newtons for harness webbing and 15,000 Newtons for LA and tether webbing. To get an idea of how strong that is, you could basically pick up a Honda Accord with a strap made out of LA or tether webbing!
CR manufacturers purchase this strong webbing, and most also do their own internal testing to doubly ensure compliance with the standard. FMVSS 213 specifies that this be done using what’s called a quasi-static test. This is simply a test in which the webbing must not break, at the specified load, when a device attached to the ends pulls it apart at a slow and steady rate.
The quasi-static test is beneficial as a consistent benchmark for measuring performance criteria among all the different webbings that a company might use. However, CR manufacturers also assess webbing during dynamic testing of car seats during sled tests run at a very high rate of speed. Quasi-static results typically do not match these high-speed results, in that the amount of elongation (or stretch) seen during the quasi-static test is likely to differ from the amount during a sled test—it could be more or less. Since the amount of stretch is a key characteristic with respect to how webbing manages crash forces, it is helpful to know the results of both types of testing.
Now back to the guts of the story. We’ve observed that webbing comes in different styles with varying construction. Why? Because, depending on the configuration of the fibers (threads), webbing will stretch to varying extents when loaded by crash forces, such as in a sled test or actual car crash. Rather than considering one type the best, engineers make use of this variability.
Like car seats, webbing types can perform differently in FMVSS 213 crash testing, and the actual car seat it is attached to will further differentiate the results. Sometimes the webbing selected during car seat design may even cause the CR to crack during the development and testing phases. By simply making a better choice for the type of webbing, the same car seat may pass testing without any other changes to the CR being needed. When looking at the performance criteria in FMVSS 213, differences in harness webbing can influence the results of the test dummy head injury criterion (HIC) score and Chest G injury criteria, as well as the head and knee excursion (forward movement).
As CPSTs know, the management of crash forces requires give and take. While one goal is to hold a CR in place, injury may result if the body isn’t allowed to slow down gradually enough. Therefore, while webbing used for LATCH installation must be strong and hold the car seat in place, car seat engineers carefully select the kinds of webbing used for a particular car seat model to balance the CR’s overall performance.
For instance, some car seat models may have tether or lower anchor webbing that has a relatively high elongation in order to enhance the performance of the CR structure. While this would increase some excursion measurements (a negative effect), this might be a net-positive tradeoff if it lowers the dummy HIC or chest Gs enough (a positive effect). In fact, because tethers do such a good job of supporting a CR and controlling head excursion, there is usually some room to use webbing that stretches more if the overall effect is a more structurally sound CR that measures better HIC and chest Gs in testing—a tradeoff that is likely to translate to better outcomes for real children in crashes.
Webbing variations can also be especially useful to engineers in the late stages of CR development. To CR engineers, these final stages are all about tweaking or “turning the dials” until you get the best performance possible in all the measurable categories: HIC, chest G’s, head excursion, knee excursion, and structure. What does turning the dials mean? Well, before a car seat is even made, developers use a variety of tools, like computer-aided design programs and 3-D printed models, to predict a CR’s fit, performance, and function, because changes made after a CR is molded are very costly. But, until it has been physically made, it is difficult to really know for sure how a CR will perform in every test configuration. So CR manufacturers have a few go-to ways to tweak performance during the final development stage. Having a wide selection of webbing to try is an important one of those, giving them so-called “dials” to turn. By matching the right webbing to a CR, manufacturers can fine-tune it so it performs to its best potential.
I hope this sheds some light on how CR manufacturers choose webbing, just one of the many factors that can influence the performance of a car seat. In particular, consider this when asked why owners are prohibited from swapping components of different car seats, even if the parts are from the same manufacturer. When it comes to webbing (and other parts, as well), rest assured that there were important reasons the CR developers used the particular type that they did for each model. So, even if parts seem similar to the untrained eye, making changes to a CR that are not approved by the manufacturer can truly have negative consequences on performance. |
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