Saber Ben Abdessalem

Tensile and Knot Performance of Polyester Braided Sutures

The success of a suture is generally linked to its mechanical performance such as tensile strength and knot slippage. The measurement of the tensile properties of sutures suffers from the absence of an international standard test method. In this paper, we present an experimental procedure for the measurement of mechanical parameters and knot slippage of braided sutures made of polyester fibers. The effect of braid angle on tensile and knot performance was studied, and a slippage ratio obtained from load-extension curves was defined. The variation of braid angle had an important influence on breaking load and elongation of the suture. The presence of a knot lowered the breaking load and the rupture occurred consistently at the knot region. The slippage ratio permitted the comparison of the resistance to slippage of different types of knot.

Mechanical behavior of a textile polyester vascular prosthesis : Theoretical and experimental study

Woven and knitted cardiovascular prostheses are tubular structures made of polyester filaments. They are used as bypasses to derive blood circulation or to replace failed blood vessels. The conditions of use require particular mechanical properties of the graft, such as elasticity and bending. A theoretical model, based on elasticity hypotheses, and a pulsatile flow system were used to determine the mechanical behavior of a knitted vascular graft under fluid pressure. For steady flow, prosthesis bending evolves in direct ratio to pressure. In pulsatile flow conditions, the prosthesis bends but not in proportion to the fluid pressure, showing instead a viscoelastic behavior by the textile structure.

Contribution to the optimisation of artificial ligament mechanical properties

Abstract In this work, artificial anterior cruciate ligaments were manufactured using braiding process. The mechanical behaviour of circular braids under tensile loads was studied. These braids were manufactured from different yarns and materials. A study of the effect of yarns characteristics and the machine parameters on the braid mechanical properties was done. Predictive models of the braid mechanical response based on the constituent yarn characteristics and the machine parameters have been developed. The last part of this study has been devoted to optimise the braid mechanical properties to be close to those of native ligament.

Blood Flow in a Polyester Textile Vascular Prosthesis: Experimental and Numerical Study

Textile cardiovascular prostheses are woven or knitted structures made of synthetic filaments. They present particular mechanical properties linked to the nature of yarn interlacing and the wavy form of their walls. Steady and pulsatile blood flows are studied in such a prosthesis. The results show that a prosthesis cannot be considered as a fiat-walled graft. These results also demonstrate that the flow velocity near a prosthetic surface is strongly influenced by the morphology of the crimping. A local flow analysis is imperative to understanding pathologies implying hemodynamic factors and to optimizing prosthesis design.

Optimization of textile parameters of plain woven vascular prostheses

This paper investigates and reports the effect of some textile parameters (yarn and fabric parameters) on the main performances of plain woven vascular prostheses in order to enhance their overall quality. We weaved tubular structures with different fabric densities using texturized Dacron® polyester filament yarns with different linear densities and filament counts, in warp and weft directions. The performances of the manufactured samples, such as wall porosity, water permeability and mechanical features, have been tested. By adopting a two‐level fractional factorial design of experiments, the responses were fitted to predictive models using a multiple linear regression method. The models were tested by variance analysis and validated by correlation between measured and predicted values. We determined the optimum settings of main textile parameters enhancing plain woven vascular prosthesis quality by contour plots method.

New test methods to evaluate the performance of dermatological braided sutures from both the doctor and the patient sides

Test methods and instrumentations to measure suture tensile performances have been limited to single‐pull to failure and knot‐pull strength. Though useful, these tests do not thoroughly represent the stresses that sutures experience during wound healing. This paper proposes new test methods to evaluate the performance of dermatological sutures using slippage ratio and recovery deformation based on a realistic representation of suture geometry in wounds. For demonstration purposes, we compared three dermatological knots: square, surgeon’s square, and surgeon’s granny. Our results confirmed that the knot design and the generated internal forces in the knot led to significant change in suture behavior during the tying and healing process. Suture performance depended greatly on the intensity of internal forces and the ability of knot packing. Among the studied knots, the square knot had the lowest slippage ratio because it showed the best aptitude to tightening, while the surgeon’s knot exhibited the highest deformation recovery due to its lower locking ability.

Hysteresis measurement for characterising the dynamic fatigue of textile artificial ligaments

A new fatigue tester simulating the movement of the knee is designed and developed in this paper. This fatigue tester allows us to combine simultaneously cyclic solicitations: bending‐traction and twist. The objective of the investigation is to determine the dynamic fatigue behaviour of braided ligaments made of polypropylene by using hysteresis measurement. The combined cyclic solicitations generate new mechanical properties expressed by hysteresis loop of the braided structure. The hysteresis loop supplies energy dissipation depending on the number of cycles and sample preconditioning. The new behaviour of the solicited braid and the residual deformation is discussed.

Effect of finishing resins on mechanical and surface properties of cotton Denim fabrics

Abstract The effect of two famous finishing resins; acrylic resin (Resacryl M), and Glyoxal resin (Resinol AM), applied by the same Pad Dry Cure Process PDC but according to various conditions, on the mechanical and surface properties of different cotton denim fabrics is studied in this paper. The treated samples which are characterized at two steps of the treatment process: before and after washing (BW and AW) were characterized in terms of surface morphology observations by SEM, geometrical roughness measurements with Kawabata Evaluation System KES, thickness and Dry crease recovery angle DCRA measurements, and mechanical testing properties. It resulted that Resinol AM improves dry crease recovery angle, but causes a loss of strength in the warp direction. Nevertheless, Resacryl M improves handless and preserves the mechanical properties fabric before and after washing. Studying the effect of resins type, concentrations and curing temperature on the mechanical behavior and surface of the cotton fabrics is very important in textile laundering, because it allows choosing the best finishing agents and conditions. Furthermore, the results of this report will be in workable data to predict the properties of the treated fabrics after resin finishing.

Dimensional Stability of Men's Socks

Dimensional stability is one of the main quality problems of men’s sock manufacturing. Major shrinkage can be found after washing, undermining socks’ usability. Today, greater demand for quality is required as customers become more aware of shrinkage from laundering. In order to investigate the effect of pressing and repeated launderings on dimensional stability of men’s socks, three commonly produced socks were subject to pressing at different temperatures and for different lengths of duration by an industrial sock pressing machine. The study demonstrates that pressing causes major shrinkage in the body and sole zones. The shrinkage is inversely proportional to temperature and duration of the pressing process. After the first laundering, major shrinkage was found. The second laundering had no significant effect on dimensional variations since the sock had already taken up its fully relaxed dimensions. The results can help knitters predict sock dimensions after thermal and humid treatments.

Investigation of PET-Braided Vascular Stents Potential Compared with Commercial Metallic Stents

Braided polymeric biomedical stents were developed as an alternative to replace commercial metallic ones presenting several failures caused especially by the used metals. Among those materials, the polyethylene terephthalate PET has been used to develop stents since it is suitable for several biomedical uses, such as vascular prosthesis. But in order to obtain the ideal PET-braided stent, its manufacturing parameters should be carefully chosen. For that, the current study aims at developing polymeric braided vascular stents made of PET monofilaments. According to a two-level fractional factorial design, stents are braided by varying most of their manufacturing and heat-setting parameters (monofilament diameter, stent diameter, braiding angle, heat-setting temperature and heat-setting time). Then, the structural (cover factor, porosity, unchanged bending diameter) and mechanical tests (radial compression, longitudinal compression, longitudinal elongation) are performed. Developed stents performances are compared to those of the Gore’s Nitinol stents. Then, effects of manufacturing parameters on stents properties were investigated. After selecting the significant parameters for each performance, optimal values were determined. According to the experimental results, manufactured stents showed good performances comparing to Nitinol stents. According to the factorial analysis, considered factors have different effects from a response to another. The most common significant factors are monofilament diameter, stent diameter and braiding angle, whereas the least important factors are heat-setting temperature and heat-setting time. Also, models are adequate (p-value 80%) at the 95% confidence level. Furthermore, the obtained optimum stent’s manufacturing settings can lead to PET-braided stents as performant as Gore’s Nitinol ones.