Nancy Powell

Multi-fiber needle-punched nonwoven composites: Effects of heat treatment on sound absorption performance

Nonwovens have been increasingly used in car interiors for noise reduction. Most of these nonwovens are subjected to thermal treatments to give the nonwovens their final three-dimensional forms. Therefore, it became crucial to investigate the effects of thermal treatment on sound absorption characteristics of nonwovens. In this study, the effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of thermally treated three-layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature and duration. The thermally treated three-layered nonwoven composites are classified into three types based on the material content and fiber blend. Sandwich structures consisting of polylactide/hemp/polylactide and polypropylene/glassfiber/polypropylene layers were called LHL and PGP, respectively. The sample which consisted of three layers of an intimate blend of polypropylene-glassfiber was named as PGI. Both temperature and duration of thermal treatment have been found to affect air flow resistivity and sound absorption. An increase in air flow resistivity and a decrease in sound absorption have been detected with heat treatment. A similarity has been observed between the thermal behaviors of PGP and PGI, which included the same thermoplastic polymer fiber. Variation in air flow resistivity of sandwich structure nonwoven composites increased with the increase in temperature, which was not observed in the intimate blend ones. The air flow resistivity of heat-treated nonwovens followed a steeper trend compared to unheated nonwovens per change in material parameters. In terms of treatment parameters, the difference between the thermal treatment and the melting point of the thermoplastics constituent of the nonwoven composite was found to be a significant factor on sound absorption. This effect of treatment temperature on sound absorption changed with treatment duration. The sound absorptive characteristic of the nonwoven composites in terms of sound frequency underwent a change with thermal treatment due to the structural changes with exposure to high temperature.

Hemp-fiber based nonwoven composites: Effects of alkalization on sound absorption performance

The effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of alkalized three layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature, duration and concentration. The alkalized composite was a three-layered nonwoven sandwich structure consisting layers of Polypropylene/Hemp/Polypropylene. Alkalization treatment has been found to result in a loss of basis weight and a decrease in air flow resistivity. Among treatment factors, only temperature was found to be a statistically-significant factor on air flow resistivity. Higher-temperature alkalization leads to higher air flow resistivity compared to the lower-temperature treatment. Alkalization at higher temperature and higher concentrations gives better results in normalized sound absorption performance compared to lower-temperature and lower-concentration treatments, respectively.

New textile product development: Processes, practices, and products

Abstract With todays global competitive marketplace, new textile product development requires a design, marketing, materials and technology interface. An opportunity existed to examine the new textile product development processes being used by global textile companies with a variety of textile product end-uses: apparel, home textiles, transportation, industrial, nonwovens, carpets, and medical textiles. The Crawford and DiBenedetto model (2003) was used as the conceptual framework for the study and data was collected using secondary and primary data sources. A total of 24 global companies, based in the United States, comprised the sample for this study. Each companys new textile product development processes, practices, and new products were examined, with identification of key new product development concepts being utilized. Results indicated that companies were utilizing new product development (NPD) processes as a competitive tool, but are using a combination of NPD strategies to develop and launch products in the global marketplace.

The development of specialized knitted structures in the creation of resist-dyed fabrics and garments

Abstract Seamless knitting proposes to offer numerous advantages to consumers and producers including better fit, improved performance characteristics, quick turn-around time, reduced system costs, and consistent quality. Although seamless knit is established in intimate apparel, extension of the technology to outerwear has been slow to attract consumers. One way to add value to seamless knit products is to create unique surface patterning to enhance the appearance. This research investigates the possibilities of resist-dyed structures on knitted fabrics, including garments created by computerized seamless-knitting technology. Resist-dyeing techniques have been traditionally created by numerous hand methods around the world, such as wax resist, yarn resist, and tied-fabric resist. This research shows a new analysis and interpretation of conventional tied-fabric resist methods by incorporating advanced knitting technology.

A textile- based optical fiber sensor design for automotive seat occupancy sensing

In our previous publications, the response of perfluorinated (PF) graded index (GI) POFs (62.5/750, 62.5/490 μm) to bending, tensile loading, and cyclic loading was investigated. The results showed that Cytop-1 (62.5/750 μm) was more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to Cytop-2 (62.5/490 μm). In this study, a textile-based optical fiber sensor was designed and the effect of automotive seat covering including face material and foam backing on a sensor’s performance was analyzed. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21 N/cm2, where PF GI POF (62.5/750 μm) was used as the POF material. The responses of the sensor in this interval were observed to be accurate and reproducible. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor response. Artificial neural network (ANN) was used for data analysis, and Qwiknet (version 2.23) software was used to develop ANNs. According to the results of Qwiknet, the prediction performances for training and testing data-sets were 75 and 83.33%, respectively.

An investigation of seam strength and elongation of knitted-neck edges on complete garments by binding-off processes

Binding off is utilized to finish a column of stitches on knitted fabric edges. A binding-off process can be performed by manual or mechanical methods involving hand knitting, overlocking, and linking processes. Binding off also can be achieved on automated flat-knitting machines by a combination of loop transfer and racking techniques. A binding-off process on the computerized knitting machinery provides several potential benefits such as minimizing labor intensive sewing or linking processes, production of constant quality products, and other benefits. However, in order to obtain the bound-off knit edges on computerized knitting machines, it is significant to not only provide appropriate values of loop lengths and machine tensions but also to choose suitable types of binding-off methods. This research introduces three different types of binding-off processes on neck edges conducted on automated complete garment knitting machines and investigates the seam strength and elongation of the neck edges by the three binding-off methods.

The response of polymer optical fiber (POF) to bending and axial tension for the application of a POF sensor for automotive seat occupancy sensing

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490 μm, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750 μm) ≥ 38.10 mm, Cytop-2 (62.5/490 μm) ≥ 44.45 mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2 mm gage length at a strain rate of 4 mm/min were determined: Cytop-1: 3% ≤ x ≤ 3.5%, Cytop-2: 3.1% ≤ x ≤ 3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing.

The response of polymer optical fiber (POF) to cyclic loading for the application of a POF sensor for automotive seat occupancy sensing

The goal of this research aimed to develop an accurate and reproducible textile-based optical fiber sensor for automotive seat occupancy. In our previous publication, the response of perfluorinated (PF) graded index (GI) polymer optical fibers (POFs) (62.5/750 and 62.5/490 μm) to bending and tensile loading was investigated. In this study, the response of the PF GI POFs to cyclic loading was investigated. The repeated loading and unloading the POF sensor would experience due to car vibrations and multiple uses by seat occupants, might cause fatigue failure to the POF sensor. The results showed that the Cytop-1 did not show any permanent deformation up to 500 cycles at strain rates 4 and 60 mm/min at a gage length of 76.2 mm in its elastic sensitive strain region. The Cytop-2 showed permanent deformation at 3.5% strain after 500 cycles at a gage length of 76.2 mm. Thus, the Cytop-1 was found out to be more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to the Cytop-2. In this study, a theoretical approach of the behavior of PF GI POF to cyclic loading was also provided.

Prioritizing Sensor Performance Characteristics for Automotive SeatWeight Sensors in Quality Function Deployment (QFD)

Quality function deployment (QFD), a key tool to convert the customer needs into product features, is generally integrated into the New Product Development (NPD) process at the design stage. Prioritizing customer needs in a QFD process leads to using the resources (time, money, and staffing) effectively by eliminating the unimportant customer needs. The overall goal of the research was to develop a textile-based optical fiber sensor for automotive seat occupancy. The findings of this paper were focused on the design of experiments in our previous publication. In this paper, a research study was conducted to better understand market demands in terms of sensor performance characteristics for automotive seat weight sensors, as a part of the QFD House of Quality (HOQ) analysis. A survey was sent to more than 20 companies operating in the field of automotive seat weight sensors, and Original Equipment Manufacturers (OEM) via e-mail. Only five companies participated in this study due to competitive concerns and confidentiality reasons. However, the companies responded to the survey were of quality relevant to the research and could be perceived as representative of the group of experts. All 5 companies participated in the survey agreed on the first 5 most important sensor characteristics: reproducibility, accuracy, selectivity, aging, and resolution, where The Analytic Hierarchy Process (AHP) was applied to prioritize the sensor characteristics.