This paper depicts characteristics of degradation of walls of bioreactors made of polymethylmethacrylate (PMMA) which was used to culture algae. The degradation processes take place stimulated by lighting of external surface and interaction with cultured species on internal surface. Results presented are representative for degradation of a bioreactor tube after the 4-year cultivation of Chlorella sp. Microscopic observations, roughness and transmission tests showed that changes have occurred on the inner surface. The result of use is a decrease in transmission and an increase in roughness. Microscopic observations showed that particles remained after culture, especially in cracks.

The low-cycle deformation of 304L austenitic stainless steel was examined in terms of energy conversion. Specimens were subjected to cyclic loading at the frequency of 2 Hz. The loading process was carried out in a hybrid strain–stress manner. In each cycle, the increase in elongation of the gauge part of the specimen was constant. During experimental procedures, infrared and visible-range images of strain and temperature fields were recorded simultaneously using infrared thermography (IR) and digital image correlation (DIC) systems. On the basis of the obtained test results, the energy storage rate, defined as the ratio of the stored energy increment to the plastic work increment, was calculated and expressed in reference to selected sections of the specimen. It was shown that, before the specimen fracture in a specific area, the energy storage rate is equal to zero (the material loses the ability to store energy), and the energy stored during the deformation process is released and dissipated as heat. Negative and close-to-zero values of the energy storage rate can be used as a plastic instability criterion on the macroscale. Thus, the loss of energy storage ability by a deformed material can be treated as an indicator of fatigue crack initiation.

Reverse engineering (RE) aims at the reproduction of products following a detailed examination of their construction or composition. Nowadays, industrial applications of RE were boosted by combining it with additive manufacturing. Printing of reverse-engineered elements has become an option particularly when spare parts are needed. In this paper, a case study was presented that explains how such an approach can be implemented in the case of products with asymmetric mechanical properties and using replacement materials. In this case study, a reverse engineering application was conducted on a textile machine spare part. To this end, the nearest material was selected to the actual material selection and some mechanical tests were made to validate it. Next, a replacement part was designed by following the asymmetric push-in pull-out characteristic. Finally, the finite element analysis with Additive Manufacturing was combined and validated experimentally.

This research introduces a new hydroxyapatite-based composite, designed as a bone-implant scaffold—easy, quick, economical, and closely mimicking the structure of natural bone. Additive manufacture was used to print bioactive material to form a scaffold structure. Thus, during the experimental research, three different composite materials were made to examine both their mechanical and morphological properties. Numerical modeling was used to maximize and prove the mechanical and biological performance of the HA-polymer grafts. The obtained results indicated that incorporating HA and Mg particles into a polymeric matrix allows the structure to be used in tissue engineering. Best results were obtained using a structure, designed from PLA and PHA at 30%, PHB at 25%, Mg at 5%, and HA at 10%. The composite was distinguished by its lightness, strength, and biocompatibility, making it suitable for tissue engineering.

Hemp-based mycelium composites are promising bio-based materials, but their heterogeneous structure may strongly affect mechanical performance and stability under water exposure. Six hot-pressed composites based on hemp hurds and chopped hemp straw, colonized with Pleurotus ostreatus or Ganoderma applanatum, were investigated. Depending on formulation, spent coffee grounds, thermoplastic or plasticized starch, and polymeric components introduced as granules, film flakes, or poly(ε-caprolactone) meshes were incorporated. Apparent density, water absorption, dimensional changes during immersion, compression, and three-point bending were evaluated. Mean apparent density ranged from 0.69 to 0.96 g × cm⁻³ and showed a positive specimen-level association with maximum compressive stress within the investigated plates (Spearman’s ρ = 0.845, n = 30). Because only one plate was manufactured per formulation, the observed formulation-specific property profiles represent exploratory observations within the investigated manufactured plates rather than population-level estimates of formulation effects or manufacturing reproducibility. The highest mean maximum compressive stress was 5.7 ± 1.2 MPa, whereas the highest mean maximum flexural stress and flexural modulus were 4.6 ± 2.1 MPa and 627 ± 285 MPa, respectively. Water uptake, dimensional swelling, and retention of measurable integrity followed different formulation-dependent trends; the greatest through-thickness swelling did not necessarily correspond to the fastest loss of cohesion. Overall, density, mechanical response, water uptake, dimensional deformation, and wet-state integrity were related but distinct descriptors of material performance, highlighting the need for multi-property optimization.