Foam Liner Research Articles

Helmets with lattice liners can mitigate traumatic brain injury from impacts

This study explores the effectiveness of architected lattice structures, specifically made of polyamide 12 (PA12) material, as potential helmet liners to mitigate traumatic brain injuries (TBI), with a focus on rotational acceleration. Evaluating three lattice unit cell topologies (simple cubic, dode-medium, and rhombic dodecahedron), the research builds upon prior investigations indicating that PA12 lattice liners may outperform conventional EPS liners. Employing a high-fidelity finite element male head model and utilizing direct and oblique impact scenarios, mechanical quantities, such as maximum principal strain (MPS) and shear strain, cumulative strain damage measure and intracranial pressure were measured at the tissue level in different brain regions. Results indicate that lattice liners, especially with dode-medium topology, exhibit promising reductions in brain tissue strains. On average, during oblique impacts, less than 1 % of the brain volume experienced an MPS level of 0.4 when the lattice liners were adopted, whereas that percentage was above 70 % with the expandable polystyrene (EPS) foam liners. Pressure-based assessments suggest that lattice liners may outperform EPS liners in oblique impacts, showcasing the limitations of EPS for effective TBI mitigation. Despite certain model limitations, this study emphasizes the need for advancements in helmet technology, particularly in the development of commercial lattice liners using additive manufacturing, to address the limitations of existing EPS liners in preventing rotational consequences of impacts and reducing TBI.

Multi-objective optimization of prosthetic multi-cells foam liner

Restoring mobility using prosthetic limbs anchored in custom sockets is the primary goal of amputee rehabilitation. The contact pressure at the stump-liner interface is critical for improving prosthetic socket design and enhancing amputee satisfaction and comfort. This study aimed to develop and optimize a new customized multicellular foam liner model by identifying the optimal configuration of the liner’s cells to achieve minimal contact pressure between the transtibial limb (stump) and the prosthetic interface while simultaneously minimizing the stump’s immersion in the foam liner. The study employed a multi-objective optimization using the NSGA-II genetic algorithm to optimize the material configurations of the liner cells. The objective function was based on a finite element (FE) model of the customized foam liner, composed of 40 cells, each using one of six foam materials with varying firmness. The optimization process yielded nine different configurations representing the Pareto front. Contact pressure and immersion, represented by displacement in the load direction, were reduced from 140 KPa and 9 mm to 10 KPa and less than 1 mm, respectively. The results obtained in this study motivate future clinical trials on the efficacy of customized multicellular foam liners. These findings provide in-depth insights into prosthesis design and customization, potentially leading to further development in the use of foam rather than silicone for liner manufacturing.

EXPERIMENTAL STUDIES OF A DAMAGED BEAM REINFORCED WITH FIBER CONCRETE

The paper presents the results of a study of the load-bearing capacity of a beam damaged during hostilities, which was reinforced with steel fiber concrete. A beam with 20% damage in the compressed zone is considered. Before concreting, a foam liner was installed in the area of the planned damage, the shape and dimensions of which corresponded to the planned damage. After the concrete gained 70% of the brand strength, the liner was removed, and the resulting cavity was filled with a 2% mixture of fiber-reinforced concrete. This is one of the options for strengthening a beam in a comprehensive testing program for damaged beams, which involves studying a series of beams with different types of damage, damage zone (tension and compression) and its size, geometry and method of strengthening. The authors have developed a special stand for testing. Plane transverse bending of the loading of the beam under test is created using a hydraulic jack and a metal I-beam with a traverse that transmits two equal concentrated forces to the beam. The created load is controlled by an exemplary dynamometer of the Tokar system and a ring dynamometer, which acts as a support. Experimental studies have shown that a beam, the cross-section of which is 20% damaged in the middle compressed zone, and the shape of the damage is close to rectangular, has a load-bearing capacity of 93.6 kN, which is 95.0% of the load-bearing capacity of an undamaged beam (98.5 kN). Crack formation began on the 5th stage of loading, when the load value was 32.5 kN, that is, 34.7% of the load-bearing capacity of the damaged beam. In this case, 4 cracks formed in the pure bending zone. At the sixth stage, three more cracks appeared. At stages 9, 10 and 14 of loading, 7 more cracks formed. The maximum final crack opening width was 0.8 mm. throughout the testing process, the fiber-reinforced concrete liner worked with the beam as a single unit. It can be argued that strengthening a beam with 20% damage in the compressed zone using the method considered in the work makes it possible to achieve its load-bearing capacity, which is 95% of the load-bearing capacity of an undamaged beam.

Development of habitat suitability criteria for macroinvertebrate community metrics for use in habitat restoration projects

Community-based macroinvertebrate habitat suitability criteria are needed for two reasons: (1) community-based criteria, such as with macroinvertebrates, are a better measure of ecosystem health than single-species habitat suitability criteria (HSC); and (2) if food rather than physical habitat is the limiting factor for juvenile salmonids, it is better to evaluate habitat restoration projects based on macroinvertebrate habitat than juvenile habitat. The goal of this study was to generate habitat suitability criteria for macroinvertebrates in the Sacramento River. Habitat suitability criteria were derived for three macroinvertebrate community metrics. One of the metrics (biomass of baetids, chironomids and hydropsychids) was selected to represent food supply for juvenile salmonids, while the other two metrics (total biomass and diversity) were selected as measures of ecosystem health. Baetidae, Chironomidae and Hydropsychidae were chosen because they are the dominant taxa present in stomach contents samples of Sacramento River juvenile Chinook Salmon Oncorhynchus tschawytscha. Habitat suitability criteria were developed using data from 75 macroinvertebrate samples stratified by season, mesohabitat type, depth, velocity, and substrate. The criteria for depth, velocity and substrate were developed taking into account several potential confounding variables, and using a polynomial regression for depth and velocity, and analysis of variance for substrate (a categorical variable). The criteria showed no effect of substrate on baetid/chironomid/hydropsychid biomass or diversity. Criteria for total biomass showed a higher suitability for larger cobbles, versus other substrates, for total biomass. The optimum depths for baetid/chironomid/hydropsychid biomass, total biomass and diversity were, respectively, 0.82–0.85 m, 0.61–0.67 m and 1.16–1.19 m. The optimum velocities for baetid/chironomid/hydropsychid biomass, total biomass and diversity were, respectively, 0.73–0.79 m/sec, 0.61–0.67 m/sec, and 0.61–0.73 m/s. Suggestions for development of future macroinvertebrate HSC include: (1) stratifying sampling by depth, velocity and substrate; (2) measuring the amount of organic matter in samples for use as an additional potential confounding factor; and (3) sampling a large area (0.84 m2) with a sampler with a rubber foam lining on the bottom of the sampler.

Evaluation of metal foam liners for broadband noise reduction of turbofan engines

Previous research shows that open-celled metal foam liners have the potential to provide substantial aircraft noise reduction benefits. Our recent results show that their normal incidence sound absorption performance can be further improved by compressing them uniformly; this compression reduces their effective pore size and increases the thermoviscous losses. Further, their performance may be optimized by stacking foams with varying degrees of compression and creating a step-wise effective relative density gradient. Here, we present the results from our recent experiments, evaluating the attenuation performance of such a step-wise gradient metal foam liner using the Advanced Noise Control Fan (ANCF). Liner spools with two different step-wise configurations were fabricated and tested using the ANCF test rig at the Notre Dame Turbomachinery Laboratory. Farfield data was gathered with the liner spool mounted at the inlet and aft locations. In this paper, we present our results comparing the attenuation performance under both test conditions as compared to measurements obtained using a hard wall baseline configuration. Our results show that step-wise metal foam configurations can provide robust acoustical performance for aircraft noise reduction applications.

Effect of personalized liner thickness on the stresses at the stump-prosthesis interface

After trans-tibial amputation (TTA) the patient needs prosthesis to maintain mobility, unfortunately, people with this type of amputation often experience skin degradation due to the pressures and shear stresses in the stump-prosthesis interface. The purpose of this study was to reduce the contact pressures and shear stresses at the stump-prosthetic interface In order to design a satisfactory and comfortable prosthesis for the patient. To achieve this we built a trans-tibial finite element model (FE) (stump, socket, and bone, liner) to investigate the stresses at the stump-prosthetic interface. This (FE) model allows comparing the effect of three types of the prosthetic liner (gel liner, Polyurethane foam liner, liner with two layers of foam (foam polyurethane - natural rubber latex foam)) on the contact pressure and shear stress at the stump-prosthetic interface. By modifying the liner thickness (from 3 to 9 mm) in all three cases, one also aim to determine the effect of liner thickness variation on the distribution and intensity of the contact pressure and the shear stress at the stump-prosthetic interface. The comparison of the stresses and their distribution at the stump-prosthesis interface in each case will allow us to determine the optimal prosthesis. The liner with two layers of foam (polyurethane - latex) achieves the best balance between the ability to support the patient’s weight and low stress values at the stump-prosthetic interface, the contact pressure and shear stress values have not been exceeded 42.12 kpa and 15.4 kpa. In general, it can be said that the thickness of the liner was effective in reducing the stresses at the stump-prosthetic interface, in all three cases of liner.

Smart material and design solutions for protective headgears in linear and oblique impacts: column/matrix composite liner to mitigate rotational accelerations

Oblique impact is the most common situation that cyclists experience during traffic accidents during which the human head undergoes both linear and rotational (angular) accelerations. Angular acceleration of the head is known to be linked to the majority of traumatic brain injuries. This paper proposes various solutions to mitigate angular accelerations of which an anisotropic column/matrix composite foam design is the most effective. This smart design allows tailor-made adjustment of shear and compressive resistance of the foam liner. Regarding helmet shells, tough fiber-reinforced composite materials such as self-reinforced polypropylene (PP) (Curv®) and silk/high-density polyethylene (HDPE) were benchmarked against conventional brittle polycarbonate (PC). Results demonstrate the superior performance of silk/HDPE composite compared to PC in resisting perforation in localized impact involving sharp objects. Regarding the helmet liner, two configurations were studied particularly, a multi-layered and column/matrix design. Their efficacy was benchmarked against single-layer homogenous expanded polystyrene (EPS) foam of equivalent weight and thickness in linear and oblique impact using experimental and finite element methods. The results showed the superior behavior of the column/matrix configuration. Such smart design could be combined with other smart systems such as multi-directional impact protection system (MIPS) technology for possible synergy and enhanced performance in head protection.

Estimation of acoustic transmission loss for carbon honey comb panel with melamine foam

In this paper, the acoustic noise reduction of aluminum honeycomb/carbon face sheet sandwich panel with Melamine Foam (MF) lining of variable thicknesses (25 mm & 50 mm) is numerically estimated and then experimentally verified using impedance tube based on transfer matrix method. The presence of carbon face sheets and MF lining can have a significant impact on the Transmission Loss (TL). The impedance tube can measure the TL for frequency range of 64 Hz–6.2 kHz. A conventional, two-microphone impedance tube, is connected to a sample holder downstream of the first microphone pair and a section downstream of the sample holder that accommodates a second pair of microphones. The Finite Element Analysis and experimental results are compared and found in good agreements. The TL levels for each layer of material is estimated prior to have TL for combined structure. Furthermore, the optimized insulation foam thickness of 50 mm is obtained based on required acoustic parameters.

In Situ Strain Measurements Within Helmet Padding During Linear Impact Testing.

Drop and Impact testing of helmets are used extensively in the design process and eventual certification of helmets. These techniques have traditionally relied heavily on the measurement of the kinematic response to impact, which provides an indirect measurement of the liner response that is subject to interpretation during the design process. In the present work, we introduce an in situ experimental technique that provides a time-resolved measurement of the deformation of the helmet and its components during an impact event. The data collected from a high-speed X-ray imaging system can provide a full description of the deformation at the component level, which provides a helmet designer further insight into the performance of their helmet, while also returning the traditional kinematic metrics. The data presented focuses on the deformation of a commercial hockey helmet subjected to a series of linear impacts with three different impactor caps at speeds ranging from 2.4 to 4.5m/s. Deformation of the liner was monitored in the midsagittal and a parasagittal plane of the helmet. The results show that there is a clear dependence on the maximum strain achieved in the foam that is dependent on the impact type, the impactor shape, and the resulting strain rate of deformation in the foam liner. These techniques can provide the first data for a direct validation and calibration of finite element helmet deformation models, while also providing a new tool-set to improve the efficacy of helmet design.

Study on protective performance and gradient optimization of helmet foam liner under bullet impact.

Protective equipment in war plays a vital role in the safety of soldiers, the threat to soldiers from brain damage caused by deformation at the back of the helmet cannot be ignored, so research on reduce blunt post-cranial injury has great significance and value. This study first conducted gunshot experiments, used rifle bullets impact bulletproof plate and different density liner foam to record the incident process and internal response of craniocerebral model. After verifying the accuracy of finite element model through experimental data, optimization model is established based on response surface method to optimize the structure of gradient foam, analyze the cranial strain and energy absorption to select the best density and thickness distribution of each foam layer. Optimization results show that liner foam which designed to have lower density and thicker thickness for impact and brace layers, higher density and thinner thickness for middle layer can significantly improve the energy absorption efficiency. Compared to the 40.65 J of energy absorption before optimization, the optimized gradient foam can absorb 109.3 J of energy, with a 169% increase in the absorption ratio. The skull strain in the craniocerebral model was reduced from 1.260 × 10–2 to 1.034 × 10–2, with a reduction of about 22%. This study provides references for the design and development of protective equipment and plays an important role in ensuring the safety of soldiers in the battlefield environment.

Impact behavior of energy absorbing helmet liners with PA12 lattice structures: A computational study

Existing helmets have a significant but limited ability to reduce the severity of brain injury and the fatality rate during motorcycle accidents. Helmet designs with a special focus on reducing head injuries caused by rotational effects have attracted great interest in recent times. This paper uses a computational approach to study the generation of new helmet designs with lattice liners made of polyamide12 (PA12) material. Three design possibilities and three distinct unit cell topologies were used to create the liners as the energy absorbing and dissipating part of the helmet. PA12 lattice samples were additively manufactured and tested under quasi-static and dynamic compression loads. The test data, showing ductile to brittle transition due to strain-rate effects, were used to validate the finite element models of the lattices. Simulations of the linear high energy and oblique impacts on the coupled headform and liner were carried out following the state-of-the-art helmet standard ECE R22.06. The findings of this study suggest that PA12 lattice liners have an excellent capability of reducing peak rotational acceleration. Many liners can outperform the protection levels offered by existing expandable polystyrene foam liners for single impacts, but at the expense of weight. The performance of the liners can be improved by choosing the topology in such a way that the stress can be distributed through the struts. Moreover, a lattice liner having a balanced energy absorption capability and stiffness would perform better than other lattice liners.

Recent bicycle helmet designs and directions for future research: A comprehensive review from material and structural mechanics aspects

Cycling becomes more and more popular for recreation, exercising and commuting in many countries. Despite the popularity of cycling, it often comes with high level of risk. Conventional bicycle helmets, with expanded polystyrene foam (EPS) liners, can effectively mitigate impact by linear acceleration. However, there has been an urgent call for further improvement in bicycle helmets, as rotational acceleration has been found to be more dominant in severe head injuries. Recent advancements in manufacturing technologies have enabled various novel conceptual ideas and designs of bicycle helmets, which are previously deemed impracticable due to complexities in structures and materials, to become feasible. There are various bicycle helmet designs in terms of structures and materials used in both the helmet shell and liner, targeting at reducing both linear and rotational acceleration. Moreover, inspired by biological structures in nature, bio-inspired structures have been developed rapidly with excellent energy absorption capacity. As a piece of protective equipment, Bicycle helmet is a representative example where researchers are attempting to apply bio-inspired structures. The objective of the paper is to review the development of bicycle helmets and recent exploration for improvement. This includes the history of bicycle helmets, current test standards, designs of conventional bicycle helmets and the latest research (e.g. material replacement and novel structures), as well as application of bio-inspired structures to helmets. This review also identifies the limitations of current designs and standards, and challenges for future investigations.

Study on the growth and redistribution of deuterium–deuterium layer driven by temperature gradient

We report results of crystal growth, layering of the deuterium–deuterium (D2) layers in cylindrical cryogenic targets. For the first time, we realized the global coverage of the D2 layer on the inner surface of the capsule through the crystal growth of D2 ice, and the control of the temperature field without the infrared radiation, foam lining, and magnetic field. Analysis of the image of x-ray phase contrast imaging shows that the thickness of the D2 layer is about 36.53 μm, and the inner surface roughness is 3.23 μm. The finite element method is applied to simulate the temperature field of the target, and the phase transition process of D2, revealing the mechanism of D2 covering the inner surface of the capsule. These initial experiments provide a new vision and method for exploring and achieving the pure crystal growth as well as layering of D2 without operation of radioactive tritium.

Substantiation of the optimal rate of straw bed in sections with different technological solution

There is no consensus among producers and agricultural practitioners as to which bedding material is the best. The choice is largely influenced by its useful properties, duration of use and high cost. Organic (straw, sawdust, wood shavings, peat, etc.), inorganic (sand) and synthetic (rubber mats; mattresses made of chopped rubber, latex, polyurethane foam lining, waterproof wax coating, etc.) materials are used for bedding. A significant part of agricultural organizations in Belarus uses winter straw. As a bedding material, it has a number of useful properties: low thermal conductivity, high moisture absorption capacity, low cost, and comfort for animals. According to the Republican standards for the technological design of new, reconstruction and technological re-equipment of livestock facilities (RNTD-1-2004), the standards for consumption of straw bedding for cows at loose housing on deep litter is 8 kg, but there are no input standards for sections with other technological solutions. The paper presents the results of studies to determine the optimal rate of straw bedding in sections with different technological solutions. Analysis of ethological reactions of animals, contamination of the skin, presence/absence of injuries on the body, temperature characteristics of the straw bedding in different seasons of the year and the economic efficiency of using different straw bedding rates has been performed. It has been determined that the optimal straw bedding rate for the general section is 4.5 kg/animal per day, for a section with a division into a feeding area and a rest area – 3.0 kg/animal per day. Application of these rates of straw bedding will enable it to be used economically without affecting the productivity and resting comfort of cows. The research results can be used in design and construction of industrial dairy complexes and storages for rough feeds.

Numerical investigation of oblique impact behavior of a helmeted headform on a windshield considering failure

A helmet, usually comprised of a composite shell, a foam liner and a chin strap, plays an important role for human head protection. Windshield glazing is a sandwiched structure which generally consists of two soda-lime glass layers bonded by a polyvinyl butyral (PVB) interlayer. In a motorcycle-vehicle accident, the rider’s head wearing a helmet (i.e. so-called helmeted head) frequently collides onto the windshield laminated glass of a vehicle along an oblique direction. Such an oblique collision commonly results in head injury, helmet failure and windshield fracture. To model the oblique collision, the validated windshield model with the intrinsic cohesive zone model is adopted for the glass fracture and glass-PVB debonding, while an existing helmet model is employed with a continuum damage method and a crushable foam model for simulating the failure of the composite shell and the foam liner. Then, different impact velocities, foam liners with different densities, impact angles and headform postures are considered to thoroughly investigate their effects on the headform response and energy absorption performance of the helmet during the oblique collision. The simulation results show that a larger density or stiffer foam liner absorbs less energy and causes a larger maximum acceleration; and a composite liner has a better comprehensive performance than a single uniform liner, while the helmet posture has small effects on headform response and energy absorption.

Optimized metal foam liners with spatially gradient properties for aircraft engine noise reduction

Recent studies conducted by NASA have identified over the rotor liners as one of the most promising avenues for aircraft noise reduction. However, conventional noise absorption technologies cannot withstand the harsh pressure and temperature conditions near the engine core. While open celled metal foams are an alternative material choice, their open porous structure results in comparatively lower absorption characteristics. In this talk, we summarize the results from our recent efforts on improving the acoustical properties of metal foams for aircraft noise reduction applications. We show that compressing the foams substantially improves their absorption coefficient because of the reduction in the effective pore size. Unfortunately, this improvement comes with an undesirable weight penalty. To overcome this, we propose an optimized layered configuration to create a step-wise relative density gradient that provides comparable absorption characteristics while being over 20% lighter than the benchmark compressed foam. Our results show that metal foam liners with spatially gradient property configurations can provide broadband engine noise reduction while minimizing the resulting weight penalty.

Biomechanical Analysis of an Improvement of Prosthetic Liner using Polyurethane Focusing at the Anterior-Distal Part of Residual Limb: A Case Study

Most transtibial prosthesis users always experience pain sensation at the distal of the residual limb due to bony prominences and nerve endings. Many initiatives have been taken to resolve this problem, including using softer materials such as silicone or gel liner and designing a distal off load prosthetic socket. Another promising approach is to incorporate polyurethane foam in the manufacturing of prosthetic liner. This study aimed to design a new prosthetic liner using polyurethane at the anterior-distal part of the residual limb as a Pelite replacement and to compare the biomechanical gait analysis between the new modified polyurethane liner and the common Pelite liner. A unilateral transtibial amputee was recruited as the subject. Two Patellar Tendon Bearing transtibial prostheses with different liners were fabricated for the subject, which were Pelite liner and a modified polyurethane foam liner. The modified liner using polyurethane foam consisted of Ethylene vinyl-acetate – Polyurethane – Ethylene vinyl-acetate sandwich placed at the anterior-distal part of the residual limb. The Ethylene vinyl-acetate – Polyurethane – Ethylene vinyl-acetate sandwich function was to improve the walking gait and compensate for the pain sensation experienced by the subject when wearing the Pelite liner. Biomechanical analysis was done using the Vicon Motion Analysis System on the subject when using the two newly fabricated transtibial prostheses and the subject’s original prosthesis with Pelite liner. During the loading response phase, the original liner exerted a slightly higher force than the Pelite and the modified liner. At 30% and 50% of the gait cycle, the original liner exerted low force than the Pelite liner and the modified liner for Ground Reaction Force at the amputated side. However, no significant difference (p>0.05) was found between all prosthetic liners for Ground Reaction Force (Non-Amputated). The biomechanical analysis showed that the modified liner using polyurethane foam improved the prosthesis user gait cycle and the walking gait of the prosthesis user.

Effect of Inorganic Nanocomposite Based Liners on Deodorization of Kimchi

This study aims to reduce the rancid odor generated during the fermentation process of kimchi by inserting zinc oxide (ZnO) into an inorganic porous material with a high surface area to decompose or adsorb the fermentation odor. ZnO activated by the presence of moisture exhibits decomposition of rancid odors. Mixed with Titanium dioxide (TiO2), a photocatalyst. To manufacture the packaging liner used in this study, NaOH, ZnCl2, and TiO2 powder were placed in a tank with diatomite and water. The sludge obtained via a hydrothermal ultrasonication synthesis was sintered in an oven. After being pin-milled and melt-blended, the powders were mixed with linear low-density polyethylene (L-LDPE) to make a masterbatch (M/B), which was further used to manufacture liners. A gas detector (GasTiger 2000) was used to investigate the total amount of sulfur compounds during fermentation and determine the reduction rate of the odor-causing compounds. The packaging liner cross-section and surface were investigated using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) to observe the adsorption of sulfur compounds. A variety of sulfur compounds associated with the perceived unpleasant odor of kimchi were analyzed using gas chromatography-mass spectrometry (GC-MS). For the analyses, kimchi was homogenized at room temperature and divided into several sample dishes. The performance of the liner was evaluated by comparing the total area of the GC-MS signals of major off-flavor sulfur compounds during the five days of fermentation at 20oC. As a result, Nano-grade inorganic compound liners reduced the sulfur content by 67 % on average, compared to ordinary polyethylene (PE) foam liners. Afterwards SEM-EDS was used to analyze the sulfur content adsorbed by the liners. The findings of this study strongly suggest that decomposition and adsorption of the odor-generating compounds occur more effectively in the newly-developed inorganic nanocomposite liners.

Bracing for infantile scoliosis: no sedation needed.

Mehta casting technique applied under anesthesia is standard treatment for infantile scoliosis (IIS). However, concern has been raised about frequent anesthesia in children less than three years. The development of a customized thoracolumbar sacral orthosis (TLSO) could avoid the risks of Mehta casting. To develop a bracing technique for IIS that achieves patient compliance and scoliosis correction. Nine patients with ISS were offered a custom TLSO as an alternative to Mehta casting. One patient declined due to an insurance issue. No anesthesia was required for measurement or fitting of the TLSO. A temperature sensitive monitor recorded wear time. Brace success was determined by radiographic correction and adherence to prescription of greater than 18 hours per day. Eight patients had brace treatment with mean(range): age 19(12-44) months, curve magnitude 34°(22-44°), rib vertebral angle of greater than 20°with follow-up 17(3-28) months. In brace correction was less than 15 degrees in 6 of 8 patients. Compliance monitor recorded wear: 4 patients ≥ 18 hours, 2 patients 16-18 hours, 1 had 14 hours, and 1 monitor malfunctioned and could not be read. Brace design evolved to maximize ipsilateral abdominal relief away from the lateral apical shift of the design. Foam lining was added to prevent skin irritation through the relief opening. Average number of braces per year =2.2. A customized TLSO can achieve in brace correction comparable to Mehta casting with acceptable compliance and without the need for general anesthesia, while allowing bathing and skin care.

Effect of multi-layer prosthetic foam liner on the stresses at the stump–prosthetic interface

The prosthetic liner plays a significant role in the redistribution of the pressure between the stump and the socket, as it adding a cushioning layer between the stump and the socket which relieves pain and makes the prosthesis more comfortable. This study employed nonlinear finite element analyses to investigate the peak pressure and shear stress at stump–prosthetic interface in the case of multi-layer prosthetic foam liner, this liner having an inner polymeric foam layer Surrounded by another type of polymeric foam layer, we used three different types of foams in different order to define this liner (flexible polyurethane foam, polyurethane-shape memory polymer foam, and natural rubber latex foam). That’s allows comparing 6 deferent configuration of multi-layer prosthetic foam liner.