RÉSUMÉ
Recent progress in additive manufacturing, also known as 3D printing, has offered several benefits, including high geometrical freedom and the ability to create bioinspired structures with intricate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal microstructures of a beetle's forewing, a mantis shrimp's shell, and a mantis shrimp's dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to determine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive performance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young's modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bending deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications.
RÉSUMÉ
Background: Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-Cog) is a widely used screening tool for detecting older adults with Alzheimer's disease among their cognitively healthy peers. A previous study in Greek population showed that ADAS-Cog-Greek (G) is a valid tool and can identify people with Alzheimer's disease from older adult control group; however, there is no current data about whether ADAS-Cog can differentiate older adults with mild cognitive impairment (MCI) from those who have subjective cognitive decline (SCD). Objective: The current study aimed to examine the discriminant potential of ADAS-Cog-G in Greek older adults who meet the criteria for SCD or MCI. Methods: Four hundred eighty-two community-dwelling older adults, visitors of the Greek Alzheimer Association and Related Disorders, were enrolled in the current study. One hundred seventy-six of them met the criteria for SCD and three hundred six had MCI. Results: Path analysis applied to the data showed that age, as well as educational level affected ADAS-Cog-G performance. Results showed that the cut-off scores, which better discriminate people with SCD from MCI as well as their sensitivity and specificity values, were extracted in participants with high educational level (13 educational years<) and mainly under the age of 75 years. Conclusions: The current study provided evidence concerning the discriminant potential of ADAS-Cog-G to differentiate older adults with SCD from those with MCI in the Greek population, and therefore contributes to the relevant literature on the field.
RÉSUMÉ
AIM: The COVID-19 pandemic caused drastic changes in older people's daily activities with a negative impact on their mental health, yet older people are less likely to seek mental health services. This study aims to explore the relationship between knowledge of and familiarity with mental health services, along with the impact of the COVID-19 pandemic, and barriers to seeking mental health services among older people. METHODS: A descriptive cross-sectional study was conducted with a convenience sample of 352 older people, recruited among community-dwelling adults who attended randomly selected postal offices and pension outlets. Three tools were used: a structured interview schedule for sociodemographic and clinical characteristics of older people, the revised version of the Knowledge and Familiarity of Mental Health Services Scale (KFFMHS-R), and the Barriers to Mental Health Services Scale Revised (BMHSS-R). RESULTS: All participants reported experiencing mental health distress during the COVID-19 pandemic. Intrinsic barriers had a higher mean score than extrinsic barriers, and 27.4% of the variance of overall barriers to seeking mental health could be explained through regression analysis by familiarity, knowledge of mental health services, and age. Overall barriers explained 24.4% of the variance of older people's perceived distress as an impact of the COVID-19 pandemic (F = 22.160, P < 0.001). CONCLUSIONS: Knowledge of mental health services was the most significant predictor of barriers to seeking mental health services during the COVID-19 pandemic. Higher barriers predicted higher distress as an impact of the COVID-19 pandemic. The results of the study suggest the need for a multidisciplinary mental health team for older people.
Sujet(s)
COVID-19 , Services de santé mentale , Humains , Sujet âgé , Études transversales , COVID-19/épidémiologie , Pandémies , Santé mentaleRÉSUMÉ
The Ti6Al4V alloy has many advantages, such as being lightweight, formal, and resistant to corrosion. This makes it highly desirable for various applications, especially in the aerospace industry. Laser Powder Bed Fusion (LPBF) is a technique that allows for the production of detailed and unique parts with great flexibility in design. However, there are challenges when it comes to achieving high-quality surfaces and porosity formation in the material, which limits the wider use of LPBF. To tackle these challenges, this study uses statistical techniques called Design of Experiments (DoE) and Analysis of Variance (ANOVA) to investigate and optimise the process parameters of LPBF for making Ti6Al4V components with improved density and surface finish. The parameters examined in this study are laser power, laser scan speed, and hatch space. The optimisation study results show that using specific laser settings, like a laser power of 175 W, a laser scan speed of 1914 mm/s, and a hatch space of 53 µm, produces Ti6Al4V parts with a high relative density of 99.54% and low top and side surface roughness of 2.6 µm and 4.3 µm, respectively. This promising outcome demonstrates the practicality of optimising Ti6Al4V and other metal materials for a wide range of applications, thereby overcoming existing limitations and further expanding the potential of LPBF while minimising inherent process issues.
RÉSUMÉ
Carbon-fibre-reinforced plastic (CFRP) is increasingly being used in various applications including aerospace, automotive, wind energy, sports, and robotics, which makes the precision modelling of its machining operations a critical research area. However, the classic finite element modelling (FEM) approach has limitations in capturing the complexity of machining, particularly with regard to the interaction between the fibre-matrix interface and the cutting edge. To overcome this limitation, a hybrid approach that integrates smoothed particle hydrodynamics (SPHs) with FEM was developed and tested in this study. The hybrid FEM-SPH approach was compared with the classic FEM approach and validated with experimental measurements that took into account the cutting tool's round edge. The results showed that the hybrid FEM-SPH approach outperformed the classic FEM approach in predicting the thrust force and bounce back of CFRP machining due to the integrated cohesive model and the element conversion after failure in the developed approach. The accurate representation of the fibre-matrix interface in the FEM-SPH approach resulted in predicting precise chip formation in terms of direction and morphology. Nonetheless, the computing time of the FEM-SPH approach is higher than the classic FEM. The developed hybrid FEM-SPH model is promising for improving the accuracy of simulation in machining processes, combining the benefits of both techniques.
RÉSUMÉ
Fused Deposition Modelling (FDM) 3D printers have gained significant popularity in the pharmaceutical and biomedical industries. In this study, a new biomaterial filament was developed by preparing a polylactic acid (PLA)/calcium peroxide (CPO) composite using wet solution mixing and extrusion. The content of CPO varied from 3% to 24% wt., and hot-melt extruder parameters were optimised to fabricate 3D printable composite filaments. The filaments were characterised using an X-ray diffraction analysis, surface morphology assessment, evaluation of filament extrudability, microstructural analysis, and examination of their rheological and mechanical properties. Our findings indicate that increasing the CPO content resulted in increased viscosity at 200 °C, while the PLA/CPO samples showed microstructural changes from crystalline to amorphous. The mechanical strength and ductility of the composite filaments decreased except for in the 6% CPO filament. Due to its acceptable surface morphology and strength, the PLA/CPO filament with 6% CPO was selected for printability testing. The 3D-printed sample of a bone scaffold exhibited good printing quality, demonstrating the potential of the PLA/CPO filament as an improved biocompatible filament for FDM 3D printing.
RÉSUMÉ
The latest advancements in bone scaffold technology have introduced novel biomaterials that have the ability to generate oxygen when implanted, improving cell viability and tissue maturation. In this paper, we present a new oxygen-generating polylactic acid (PLA)/calcium peroxide (CPO) composite filament that can be used in 3D printing scaffolds. The composite material was prepared using a wet solution mixing method, followed by drying and hot melting extrusion. The concentration of calcium peroxide in the composite varied from 0% to 9%. The prepared filaments were characterized in terms of the presence of calcium peroxide, the generated oxygen release, porosity, and antibacterial activities. Data obtained from scanning electron microscopy and X-ray diffraction showed that the calcium peroxide remained stable in the composite. The maximum calcium and oxygen release was observed in filaments with a 6% calcium peroxide content. In addition, bacterial inhibition was achieved in samples with a calcium peroxide content of 6% or higher. These results indicate that an optimized PLA filament with a 6% calcium peroxide content holds great promise for improving bone generation through bone cell oxygenation and resistance to bacterial infections.
RÉSUMÉ
This study presents a thorough experimental investigation utilising the design of experiments and analysis of variance (ANOVA) to examine the impact of machining process parameters on chip formation mechanisms, machining forces, workpiece surface integrity, and damage resulting from the orthogonal cutting of unidirectional CFRP. The study identified the mechanisms behind chip formation and found it to significantly impact the workpiece orientation of fibre and the tool's cutting angle, resulting in increased fibre bounceback at larger fibre orientation angles and when using smaller rake angle tools. Increasing the depth of cut and fibre orientation angle results in an increased damage depth, while using higher rake angles reduces it. An analytical model based on response surface analysis for predicting machining forces, damage, surface roughness, and bounceback was also developed. The ANOVA results indicate that fibre orientation is the most significant factor in machining CFRP, while cutting speed is insignificant. Increasing fibre orientation angle and depth leads to deeper damage, while larger tool rake angles reduce damage. Machining workpieces with 0° fibre orientation angle results in the least subsurface damage, and surface roughness is unaffected by the tool rake angle for fibre orientations between 0° to 90° but worsens for angles greater than 90°. Optimisation of cutting parameters was subsequently carried out to improve machined workpiece surface quality and reduce forces. The experimental results showed that negative rake angle and cutting at moderately low speeds (366 mm/min) are the optimal conditions for machining laminates with a fibre angle of θ = 45°. On the other hand, for composite materials with fibre angles of θ = 90° and θ = 135°, it is recommended to use a high positive rake angle and cutting speeds.
RÉSUMÉ
Modern aircrafts require the assembly of thousands of components with high accuracy and reliability. The normality of drilled holes is a critical geometrical tolerance that is required to be achieved in order to realize an efficient assembly process. Failure to achieve the required tolerance leads to structures prone to fatigue problems and assembly errors. Elastomer-based tactile sensors have been used to support robots in acquiring useful physical interaction information with the environments. However, current tactile sensors have not yet been developed to support robotic machining in achieving the tight tolerances of aerospace structures. In this paper, a novel elastomer-based tactile sensor was developed for cobot machining. Three commercial silicon-based elastomer materials were characterised using mechanical testing in order to select a material with the best deformability. A Finite element model was developed to simulate the deformation of the tactile sensor upon interacting with surfaces with different normalities. Additive manufacturing was employed to fabricate the tactile sensor mould, which was chemically etched to improve the surface quality. The tactile sensor was obtained by directly casting and curing the optimum elastomer material onto the additively manufactured mould. A machine learning approach was used to train the simulated and experimental data obtained from the sensor. The capability of the developed vision tactile sensor was evaluated using real-world experiments with various inclination angles, and achieved a mean perpendicularity tolerance of 0.34°. The developed sensor opens a new perspective on low-cost precision cobot machining.
RÉSUMÉ
This work aimed to study one of the most important challenges in orthopaedic implantations, known as stress shielding of total shoulder implants. This problem arises from the elastic modulus mismatch between the implant and the surrounding tissue, and can result in bone resorption and implant loosening. This objective was addressed by designing and optimising a cellular-based lattice-structured implant to control the stiffness of a humeral implant stem used in shoulder implant applications. This study used a topology lattice-optimisation tool to create different cellular designs that filled the original design of a shoulder implant, and were further analysed using finite element analysis (FEA). A laser powder bed fusion technique was used to fabricate the Ti-6Al-4V test samples, and the obtained material properties were fed to the FEA model. The optimised cellular design was further fabricated using powder bed fusion, and a compression test was carried out to validate the FEA model. The yield strength, elastic modulus, and surface area/volume ratio of the optimised lattice structure, with a strut diameter of 1 mm, length of 5 mm, and 100% lattice percentage in the design space of the implant model were found to be 200 MPa, 5 GPa, and 3.71 mm-1, respectively. The obtained properties indicated that the proposed cellular structure can be effectively applied in total shoulder-replacement surgeries. Ultimately, this approach should lead to improvements in patient mobility, as well as to reducing the need for revision surgeries due to implant loosening.
RÉSUMÉ
As research and services in the Mediterranean region continue to increase, so do opportunities for global collaboration. To support such collaborations, the Alzheimer's Association was due to hold its seventh Alzheimer's Association International Conference Satellite Symposium in Athens, Greece in 2021. Due to the COVID-19 pandemic, the meeting was held virtually, which enabled attendees from around the world to hear about research efforts in Greece and the surrounding Mediterranean countries. Research updates spanned understanding the biology of, treatments for, and care of people with Alzheimer's disease (AD_ and other dementias. Researchers in the Mediterranean region have outlined the local epidemiology of AD and dementia, and have identified regional populations that may expedite genetic studies. Development of biomarkers is expected to aid early and accurate diagnosis. Numerous efforts have been made to develop culturally specific interventions to both reduce risk of dementia, and to improve quality of life for people living with dementia.
Sujet(s)
Maladie d'Alzheimer , COVID-19 , Humains , Maladie d'Alzheimer/épidémiologie , Maladie d'Alzheimer/thérapie , Maladie d'Alzheimer/diagnostic , Qualité de vie , Pandémies , Marqueurs biologiquesRÉSUMÉ
Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.
RÉSUMÉ
OBJECTIVES: Cognitive training exercises (CTE) are promising and effective interventions to enhance cognitive reserve and slowdown cognitive deterioration in people with subjective memory impairment (SCI) and mild cognitive impairment (MCI). In this pilot study, we aimed to assess the feasibility of CTE among Egyptian adults. METHODS: Eighteen participants above 40 years old were recruited. They underwent baseline neuropsychological assessment and functional assessment. However, after receiving a 6 weeks' cognitive training, eight participants (seven with MCI and one was cognitively intact) dropped out from the study. Finally, 10 participants (8 participants with MCI, 1 with SCI and 1 was cognitively intact) completed 12 weeks of CTE and undergone the post-assessment afterward. CTE included visual, verbal, memory, executive function, visuospatial, attention, and psychokinetic exercises through onsite and home-based sessions. RESULTS: For the 10 participants who completed 12 weeks of CTE, the Wilcoxon signed-rank test showed a statistically significant change in the scores of mini-mental state examination (Z = -2.546, p = 0.011), semantic fluency test (Z = -2.913, p = 0.004), subjective memory complaint questionnaire (Z = -2.913, p = 0.004), Consortium to Establish a Registry for Alzheimer's Disease Word List (first trial: Z = -2.641, p = 0.008; Word list recall: Z = -2.825, p = 0.005), construction abilities (immediate: Z = -2.121, p = 0.034; delayed recall: Z = -2.414, p = 0.016), and Digit span test (forward: Z = -2.724, p = 0.006; backward: Z = -2.724, p = 0.006). CONCLUSIONS: The results of this study suggested that CTE are feasible among Egyptian adults, especially those with MCI, and potentially effective in enhancing global cognition and after 12 weeks of training. Future research should shed light on the efficacy of longitudinal CTE implementation in Arab adults' populations.
RÉSUMÉ
Ti-6Al-2Sn-4Zr-6Mo is one of the most important titanium alloys characterised by its high strength, fatigue, and toughness properties, making it a popular material for aerospace and biomedical applications. However, no studies have been reported on processing this alloy using laser powder bed fusion. In this paper, a deep learning neural network (DLNN) was introduced to rationalise and predict the densification and hardness due to Laser Powder Bed Fusion of Ti-6Al-2Sn-4Zr-6Mo alloy. The process optimisation results showed that near-full densification is achieved in Ti-6Al-2Sn-4Zr-6Mo alloy samples fabricated using an energy density of 77-113 J/mm3. Furthermore, the hardness of the builds was found to increase with increasing the laser energy density. Porosity and the hardness measurements were found to be sensitive to the island size, especially at high energy density. Hot isostatic pressing (HIP) was able to eliminate the porosity, increase the hardness, and achieve the desirable α and ß phases. The developed model was validated and used to produce process maps. The trained deep learning neural network model showed the highest accuracy with a mean percentage error of 3% and 0.2% for the porosity and hardness. The results showed that deep learning neural networks could be an efficient tool for predicting materials properties using small data.
RÉSUMÉ
Three-dimensional (3D) printing is a recent technology, which gives the possibility to manufacture personalised dosage forms and it has a broad range of applications. One of the most developed, it is the manufacture of oral solid dosage and the four 3DP techniques which have been more used for their manufacture are FDM, inkjet 3DP, SLA and SLS. This systematic review is carried out to statistically analyze the current 3DP techniques employed in manufacturing oral solid formulations and assess the recent trends of this new technology. The work has been organised into four steps, (1) screening of the articles, definition of the inclusion and exclusion criteria and classification of the articles in the two main groups (included/excluded); (2) quantification and characterisation of the included articles; (3) evaluation of the validity of data and data extraction process; (4) data analysis, discussion, and conclusion to define which technique offers the best properties to be applied in the manufacture of oral solid formulations. It has been observed that with SLS 3DP technique, all the characterisation tests required by the BP (drug content, drug dissolution profile, hardness, friability, disintegration time and uniformity of weight) have been performed in the majority of articles, except for the friability test. However, it is not possible to define which of the four 3DP techniques is the most suitable for the manufacture of oral solid formulations, because the selection is affected by different parameters, such as the type of formulation, the physical-mechanical properties to achieve. Moreover, each technique has its specific advantages and disadvantages, such as for FDM the biggest challenge is the degradation of the drug, due to high printing temperature process or for SLA is the toxicity of the carcinogenic risk of the photopolymerising material.
RÉSUMÉ
BACKGROUND: With greying of nations, dementia becomes a public health priority. The rising dementia prevalence escalates both health care expenses and burden, placing the entire healthcare system and caregivers under huge stress. Cognition-oriented interventions have been shown to enhance the overall cognitive performance among healthy and cognitively impaired older adults. OBJECTIVE: This article is assumed to be a steppingstone for the introduction and establishment of cognition- oriented interventions in Egypt. In addition, it aims to offer provisional guidance for health care providers in Arab speaking countries in a stepwise approach in order to establish cognition-oriented intervention services and help them to evaluate and monitor their efficacy. METHODS: Aconsortium of Egyptian and Greek specialists developed a protocol for the operations of the Ain Shams Cognitive Training Lab and the provision of cognition-oriented interventions. This protocol is based on a previous successful protocol that has been implemented in Greece for more than 10 years and is co-designed to fit the needs of older adults in Arabic speaking countries. RESULTS: The types of services offered, their objectives, recruitment of participants, delivery of interventions, measurement of outcomes and privacy policy are all outlined in the policy. CONCLUSION: Establishing the appropriate framework in which cognitive training strategies can be adapted and implemented in Arabic population, constitutes an inevitable achievement in healthy ageing and can be also assumed as a dementia prevention strategy. Moreover, setting up the first cognitive laboratory in Egypt older adults, can be a model of good practice across the Arabic countries.
Sujet(s)
Dysfonctionnement cognitif/rééducation et réadaptation , Rééducation neurologique/méthodes , Guides de bonnes pratiques cliniques comme sujet , Sujet âgé , Sujet âgé de 80 ans ou plus , Cognition , Égypte , Femelle , Humains , MâleRÉSUMÉ
AIM: mHealth can facilitate comprehensive geriatric assessment (CGA) in countries with limited geriatric healthcare facilities. It can compensate for the lack of trained geriatricians and integrate CGA in different healthcare disciplines leading to better clinical outcomes. This study assessed the usability of a self-administered geriatric assessment smartphone application. METHODS: A cross-sectional study included participants from the geriatric clinic at Ain Shams University Hospital, Cairo, Egypt. This study was performed in three phases: development and validation of an abbreviated geriatric assessment tool, and validation of the application prototype. Twenty subjects were recruited for pretesting the abbreviated assessment tool, then another 50 patients to validate this tool in a face-to-face interview. Afterwards, another 12 patients completed the prototype followed by a standardized office visit interview. Each assessment domain was evaluated in agreement with a valid reference test during the clinical interview. RESULTS: The application was simple and user friendly. The scores of each domain correlated to the reference test scores (rho = 0.59-0.93). Most of the domains exhibited good agreement with the reference tests (kappa = 0.68-1.00) (except for frailty and nutritional assessment). CONCLUSIONS: The mHealth geriatric assessment is possible and highly desirable during physical distancing and beyond. Obviously, this approach cannot substitute for clinical examination and multidisciplinary standard CGA. However, it may overcome some barriers facing the geriatrization of medicine. It would help general practitioners to provide pre-CGA evaluation, particularly in areas with limited access to formal geriatric healthcare services. Geriatr Gerontol Int 2021; 21: 222-228.
Sujet(s)
Fragilité , Télémédecine , Sujet âgé , Études transversales , Évaluation gériatrique , Gériatres , HumainsRÉSUMÉ
There is an increasing demand for flexible, relatively inexpensive manufacturing techniques that can accommodate frequent changes to part design and production technologies, especially when limited batch sizes are required. Reconfigurable multi-point forming (MPF) is an advanced manufacturing technique which uses a reconfigurable die consisting of a set of moveable pins to shape sheet metal parts easily. This study investigates the use of a novel variable thickness waffle-type elastic cushion and a variable punch-loading profile to either eliminate or minimise defects associated with MPF, namely wrinkling, thickness variation, shape deviation, and dimpling. Finite element modelling (FEM), analysis of variance (ANOVA), and the response surface methodology (RSM) were used to investigate the effect of process parameters pertaining to the cushion dimensions and type of loading profile on the aforementioned defects. The results of this study indicate that the most significant process parameters were maximum cushion thickness, cushion cut-out base radius, and cushion cut-out profile radius. The type of loading profile was found to be insignificant in all responses, but further investigation is required as the rate, and the thermal effects were not considered in the material modelling. Optimal process parameters were found to be a maximum cushion thickness of 3.01 mm, cushion cut-out base radius of 2.37 mm, cushion cut-out profile radius of 10 mm, and a "linear" loading profile. This yielded 0.50 mm, 0.00515 mm, 0.425 mm for peak shape deviation, thickness variation, and wrinkling, respectively.
RÉSUMÉ
Since the FDA approval of Spritam, there has been a growing interest in the application of 3D printing in pharmaceutical science. 3D printing is a method of manufacturing involving the layer-by-layer deposition of materials to create a final product according to a digital model. There are various techniques used to achieve this method of printing including the SLS, SLA, FDM, SSE and PB-inkjet printing. In biomanufacturing, bone and tissue engineering involving 3D printing to create scaffolds, while in pharmaceutics, 3D printing was applied in drug development, and the fabrication of drug delivery devices. This paper aims to review the use of some 3D printing techniques in the fabrication of oral solid dosage forms. FDM, SLA SLS, and PB-Inkjet printing processes were found suitable for the fabrication of oral solid dosage forms, though a great deal of the available research was focused on fused deposition modelling due to its availability and flexibility. Process parameters as well as strategies to control the characteristics of printed dosage forms are analysed and discussed. The review also presents the advantages and possible limitations of 3D printing of medicines.
Sujet(s)
Systèmes de délivrance de médicaments , Préparations pharmaceutiques , Impression tridimensionnelle , Technologie pharmaceutique , Formes posologiques , Médecine de précisionRÉSUMÉ
Auxetic structures have attracted attention in energy absorption applications owing to their improved shear modulus and enhanced resistance to indentation. On the other hand, four-dimensional (4D) printing is an emerging technology that is capable of 3D printing smart materials with additional functionality. This paper introduces the development of a NiTi negative-Poisson's-ratio structure with superelasticity/shape memory capabilities for improved ballistic applications. An analytical model was initially used to optimize the geometrical parameters of a re-entrant auxetic structure. It was found that the re-entrant auxetic structure with a cell angle of -30° produced the highest Poisson's ratio of -2.089. The 4D printing process using a powder bed fusion system was used to fabricate the optimized NiTi auxetic structure. The measured negative Poisson's ratio of the fabricated auxetic structure was found in agreement with both the analytical model and the finite element simulation. A finite element model was developed to simulate the dynamic response of the optimized auxetic NiTi structure subjected to different projectile speeds. Three stages of the impact process describing the penetration of the top plate, auxetic structure, and bottom plate have been identified. The results show that the optimized auxetic structures affect the dynamic response of the projectile by getting denser toward the impact location. This helped to improve the energy absorbed per unit mass of the NiTi auxetic structure to about two times higher than that of the solid NiTi plate and five times higher than that of the solid conventional steel plate.