Search

In this study, the crashworthiness analysis of filled and unfilled bumper beams in head-on collisions was carried out through finite element simulations. The beam design was based on popular SUV brands in India. The outer bumper or fascia was made of AA6061-T6. Various advanced filler materials, including expanded polypropylene foam (cellular), pure PM aluminum foam (cellular), carbon fiber/epoxy (fiber-reinforced composite), and glass fiber-reinforced polymer (fiber-reinforced composite), were used to fill the inner bumper beam section. Based on the type of filler for the inner bumper section, the various configurations were given a nomenclature of C-I (Unfilled), C-II (Pure powder metallurgy aluminium foam), C-III (Expanded polypropylene foam), C-IV (Carbon fiber reinforced fiber), C-V (Glass fiber reinforced polymer). Numerical simulations were conducted using Ansys Explicit Dynamics ® software. The results indicated that EPP foam-filled bumpers (C-III) performed best in terms of crashworthiness, offering both lightweight properties and effective energy absorption. CFRP-filled bumpers (C-IV) showed the next best performance, showing high energy absorption, and the highest von Mises equivalent strain among the filler materials. PM aluminum foam-filled bumpers (C-II) demonstrated improved total energy absorption compared to unfilled bumpers, whereas GFRP-filled bumpers (C-V) exhibited poor crashworthiness characteristics.

Considering the current growth of design and development activities in micro/mini-Unmanned Aerial Vehicles (UAVs), there is a significant need for thin, durable and lightweight composites for their structural applications. Robust and impact-resistant materials are deemed mandatory concerning the harsh operational conditions where these UAVs are employed. Numerical models for composite materials at various loading conditions can bring up tremendous pace in various design and manufacturing aspects of such competent and tailored engineering materials. Numerical simulations of low velocity flatwise Charpy impact are performed on carbon/aramid hybrid laminates. The modelling is based on representative volume element (RVE) micro-scale property homogenisation in ANSYS Workbench, followed by macroscale impact analysis in ABAQUS/EXPLICIT. The damage propagation was determined using the Hashin failure criteria. The numerically predicted results were validated against the experimental data concerning the energy absorbed and impact strength. The results provided by the modelling are in good correlation with the experimental observations. The numerically obtained force-time data correlated the damage propagation and failure modes observed in the post-impact damage morphology in the laminate during the non-instrumented Charpy test.

AbstractThe hip joint is one of the most essential joints for transmitting weights to the lower abdomen during day-to-day activities. Loosening of hip implants is mostly caused by wear. The wear assessment during the design stage offers a clear sense of the implant’s life expectancy, and modest adjustments in the design may also greatly enhance the implant’s life expectancy, lowering the probability of revision surgery. Linear wear is estimated at the contact surfaces of the femoral head to the acetabular cup and the acetabular cup to the backing cup in this study. In this work, oval-shaped hip implant is considered with a femoral head diameter of 28 mm, an acetabular cup thickness of 4 mm, and a backing cup thickness of 2 mm. The Archard’s law used to estimate the linear wear rate. It is observed that when the acetabular cup is made of UHWMPE and the stem, femoral head, and backing cup are made of CoCr, the least overall deformation is 0.394 mm during walking loads. When the stem is considered Ti−6Al−4 V and the acetabular cup of UHWMPE, the minimum wear between the femoral head and acetabular cup is 0.063 mm/year. During a typical standing posture, an acetabular cup-to-backing cup wear rate of 0.007 mm/year is estimated. Overall, the CoCr material combination had the lowest wear rate in the four activities considered for this work. These implants designs can be 3D-printed and further can be tested in a hip simulator under the same loading conditions.

In replacement surgery of the hip joint, an implant is replaced into the natural femur which recreates the articulation and functionally of a natural joint. Total hip replacement is significantly increasing by the day worldwide and is likely to increase by 174% by 2030. Primary revision is another major concern for total hip replacement with revision rates likely to increase by 137%. The first part of the article states the basic anatomy of the hip joint, different ligaments in the hip, the disorders associated with the joint, and evaluation of total hip arthroplasty. In the second part some of the major works are highlighted followed by a detailed discussion about different design considerations and wear-related issues in hip joints. More emphasis is given to the tribological behavior of implants under different conditions. The design aspects and several parameters which affect the wear rate in implants are summarized. Also, different testing methods which are used both in experimental and numerical techniques are reported to estimate the wear rates in hip implants with the evolution of hip implants since the early 20th century, in terms of different designs, materials and wear hip implant arthroplasty is known as one of the best advancements in healthcare. Further research is needed to establish to improve the life expectancy of hip implants.

The total hip prosthesis is considered one of the greatest advancements in orthopaedic surgery in the early 20th century. In hip implant replacement, the stem is inserted into the femur and femoral head, acetabular cup, and backing cup over the stem. This felicitates the normal range of motion and stability of an individual compared to the natural hip joint. Several different types of biomaterials are used in the total hip prosthesis. Where the combination of UHMWPE, CoCrMo alloy, and Ti-6Al-4 V alloy is widely used due to their superior mechanical properties over the others. In this work, these material combinations are used for the analysis with changes in the femoral head sizes from 24 mm to 48 mm to know the best size with the better material combination. Static structural analyses are carried out using Ansys R-19. Two sets of analyses are performed for two different material combinations between Ti-6Al-4 V, CoCr, and UHMWPE. The circular cross-shaped stem with change in femoral head sizes from 24 mm to 48 mm is used for analysis. The acetabular cup and backing cup thickness are kept constant throughout the study. The size of the acetabular cup and backing cup is considered 6 mm and 4 mm respectively. Loading and boundary conditions are considered as per the ASTM standards. Hip implant with Ti-6Al-4 V for stem and a 4 mm backing cup of CoCr and 6 mm acetabular cup of UHMWPE shown the least stress value of 203.48 MPa over all the other models which are used in the analysis. This work shows the analysis to know the effect of the change in femoral head size and also the change in material combinations used in hip implants. Further experimental work can be carried out to validate the results obtained in the current work.

Hip implants consist of a stem, femoral head, acetabular cup, and backing cup. There is a wide variety of sizes and lengths. Their adaptability is limited because of the inter-anatomical variations. There is no single fit-for-all implant design that satisfies the orthopedic requirement satisfactorily. In this work, the trapezoidal-shaped stem with three different cross-sections is considered. The femoral head size, acetabular cup thickness, backing cup thickness, and trunnion geometry were varied to arrive at the best possible combination. ANSYS R-19 was used to perform the static analysis. It is found that trapezoidal-shaped profile two has the least amount of stress and total deformation. The von Mises stresses were found to be higher when the femoral head size was between 32 mm to 40 mm in profile two. It was also observed that the femoral head with 24 mm has the least stress compared to higher head sizes. The maximum von Mises stress-induced in profile two was 141.0 MPa, the total deformation of 0.04436 mm and elastic strain of 7.6 × 10−4 mm/mm. Trunnion interface does not have a significant role with respect to the structural strength of the implant. From the findings of this study, it is inferred that profile two shaped stems with the femoral ball size of 36 mm, acetabular cup thickness of 2 mm and backing cup thickness of 1mm is best suited for the hip replacement. The major outcome of this study is the utilization of the DoE method to determine the optimized value of the implant.

Development of new materials in place of existing traditional metals and alloys to meet specific requirements is taking place worldwide. Natural fibre reinforced composites are being considered as one of the alternative materials which can find scope in indoor and low load bearing applications. The biodegradability and low density make them attractive, while inherent hydrophilic nature of the fibre is a challenge for the engineering applications. Surface modification to the fibres by chemical treatments makes them as an alternative reinforcement material in the field of composites. In the present work, Grewia Serrulata bast fibres were subjected to chemical treatments and stitched into unidirectional woven fabrics. Treated and untreated fibre reinforced laminates were fabricated by hand layup process. Sliding wear behaviour of the prepared specimens was studied as per ASTM G-99. Materials with relatively lower wear rate are preferred for the tribological applications. The study shows that acetylated Grewia Serrulata fibre reinforced and permanganate treated fibre reinforced polyester samples showed significant wear resistance compared to neat resin and untreated fibre reinforced specimens.