Average Strength Values Research Articles

Surface distribution of small-scale magnetic field on the active cool star LQ Hydrae

It is well known that small-scale magnetism dominates the surface magnetic field topologies of active late-type stars. However, little information is available on the spatial distribution of this key magnetic field component. Here, we take advantage of the recently developed magnetic field diagnostic procedure relying on the magnetic intensification of iron atomic lines in the optical. We extend this methodology from measuring a single average field strength value to simultaneous Doppler imaging reconstruction of the two-dimensional maps of temperature and magnetic field strength. We applied this novel surface mapping approach to two spectroscopic data sets of the young active Sun-like star LQ Hya. For both epochs, we found a fairly uniform field strength distribution, apart from a latitudinal trend of the field strength increasing from 1.5–2.0 kG at low latitudes to 3.0–3.5 kG, close to the rotational poles. This distribution of the small-scale field does not display a clear correlation with the locations of temperature spots or the global magnetic field structure reconstructed for the same epochs.

Pemanfaatan Limbah Keramik Sebagai Bahan Alternatif Campuran Agregat Kasar Pada Beton

In every construction and renovation project, there is often waste that is rarely reused. The utilization of ceramic waste as a coarse aggregate in concrete can be an interesting alternative because ceramic waste shares characteristics and properties similar to coarse aggregate materials, such as hardness, and has the potential to reduce negative environmental impacts and the depletion of raw materials. Therefore, this research adopts an experimental method at the laboratory of the National Education University in Denpasar by creating five different variations of cylindrical specimens, each with three samples. The ceramic waste variations used are 0%, 10%, 15%, 20%, and 40%. By using an FAS value of 0.6, the slump value was obtained, where the larger the ceramic waste mixture value, the smaller the slump value, as this occurs due to the water absorption value in the ceramic waste being 10.51%. However, despite this, the slump value still falls within the planned range of 5.0 cm to 12.0 cm, and for the planned compressive strength value, which is 175 kg/m2, the highest average concrete strength value is found in the 0% variation, which is 16.01 MPa or equivalent to 192.83 kg/cm2. The concrete with a 10% variation has a compressive strength of 15.21 MPa or 183.25 kg/cm2, the concrete with a 15% variation has a compressive strength of 15.01 MPa or 180.82 kg/cm2, the concrete with a 20% variation has a compressive strength of 13.64 MPa or 164.38 kg/cm2, and the concrete with a 40% variation has a compressive strength of 9.87 MPa or 118.96 kg/cm2. This research can be used as additional literature or as an evaluation material for further research.

Towards reducing the capital cost of manufacturing Laminated Veneer Lumbers: Investigating finger jointing solutions

The capital cost of setting up a Laminated Veneer Lumber (LVL) plant which produces continuous LVL billet products, through a continuous veneer assembly and hot-pressing processes, is significant. However, the utilisation of batch-type presses, similar to those employed in the plywood industry, could significantly reduce this initial cost and may provide new opportunities for small to medium scale operations. This process would produce shorter billet lengths which would need to be joined together to produce lengths viable for structural products. Scarf joints have been used commercially to join some veneer-based engineered wood products but have limitations, while finger joints are a common method for jointing sawn timber products and offer some key advantages but is not a common method to join veneer-based products. Consequently, this paper focusses on investigating the influence of key manufacturing parameters on the performance of finger jointed LVL. The effect of the joint orientation (horizontal or vertical), the finger length, the gluing pressure and the adhesive type on the joint strength and stiffness were investigated. The finger jointed LVL were tested in edge bending, flat bending and tension, and the results were compared to reference unjointed LVL. The bending performance of the finger jointed LVL was also compared to scarfed jointed LVL. In total 304 tests were performed. The results indicated that the average strength values of finger jointed LVL can reach up to 99% of the average strength of unjointed LVL and compares to scarf jointed LVL on flat bending. Horizontal joints, being more practical to produce for deep beams, performed similarly to vertical joints. The 25 mm joints were found to have no mechanical advantages over the 20 mm investigated finger joints. A gluing pressure lower than the Eurocode's recommended level for solid timber achieved sufficient bonding for the products to be utilised. The gluing pressure was also found not to influence the performance of the joint, for the range of pressures investigated. Both polyurethane and resorcinol-formaldehyde adhesives produced high performing products, with the latter displaying superior adhesive bond durability. The paper concludes that finger jointing LVL represents a viable solution to manufacture usable LVL lengths from short LVL billets, but have lower edge bending efficiency than scarf jointed LVL.

The uniform and robust 8-inch CVD diamond plate generated by dual-magnetic field controlled DC Jet CVD

Diamond is a highly attractive material for many applications in material science, engineering, chemistry, and biology because of its favorable properties. The preparation of large-area freestanding diamond plate can greatly reduce the production cost of diamond and promote the industrialization of diamond. In this study, the dual-magnetic field mode was introduced to optimize the magnetic field distribution in direct current arc plasma jet chemical vapor deposition (DC Jet CVD) system, and the arc plasma was effectively controlled under the coupling of electric field and magnetic field. The uniformity of the plasma distribution above the substrate surface is significantly improved, resulting in long-term stable and uniform growth of the 8-inch freestanding diamond plate. The influence of dual-magnetic field mode on magnetic field generation, arc feature, and reactive group distribution was studied. 8-inch freestanding diamond plates with an average thickness of 2.8 mm were prepared by dual-magnetic controlled DC Jet CVD. The results showed that the 8-inch diamond plate preferred a high (220) orientation, and the deviation of thickness of which was around 10 % of the averaged values. Raman spectroscopy of diamond revealed a 6.6 cm−1 of full width at half maximum (FWHM) and calculated 1.20 GPa compressive stress in the 8-inch diamond plate. By means of mechanical and thermal property measurements, the large area diamond plate shows a robust structure with the average values of three-point bending fracture strength of 987.2 MPa, and extremely high thermal conductivity of 1797.8 W/(m·k) as well. The deviation of three-point bending fracture strength and the thermal conductivity over the 8-inch diamond plate was around 7.9 % and 12.6 % of the respective averaged values.

Heated press welding: analysis of the parameters influencing the mechanical strength of hybrid PA66/PA12 thermoplastic and S235 steel sheet joints

ABSTRACT This study aims to optimize and characterize hot pressed polyamide/steel hybrid joints as a potential solution for reducing energy costs in public transport through structural lightweighting. The mechanical performance of these joints is compared to traditional bonding methods, specifically investigating two types of joints: PA66/steel and PA12/steel. A design of experiments approach is employed to explore the influence of process parameters, with a particular focus on the cooling rate and heating temperature as key factors. By determining the optimal process parameters, the study emphasizes the importance of reaching the polymer pyrolysis point and achieving the fastest cooling rate to achieve optimal results. The findings reveal that these hybrid joints exhibit comparable average shear strength values to bonded joints, showcasing their potential as effective joining methods. In conclusion, future developments in hybrid polymer/metal joining processes utilizing thermal methods should prioritize rapid and uniform heating at the polymer/metal interface to initiate pyrolysis selectively at the polymer surface for bond formation. Subsequent rapid cooling is essential to cease pyrolysis and prevent polymer degradation within its volume. These insights are crucial for successful implementation of such processes in various industrial applications.

The effect of friction spot stir welding in installing rivet double cover lap joints on 7075–T6 aluminum plate on shear strength

FSSW is a variation of FSW developed in metal processes. The principle of FSSW is rotating an object that is wear-resistant and then rubbed with a plate joint. The use of FSSW can be utilized in the installation of rivets such as in the drilling process, so this process needs to be investigated. This is because the heat caused by rotation will change the mechanical properties of the material so further research is needed. In this study, a connection performance comparison was made between the FSSW method and the drill. The plate used is aluminum 7075-T6 with a lap joint connection type. To find out each performance, a shear test, hardness test, and metallographic test were carried out. From the results of the shear strength test, it can be concluded that the FSSW variation is the best with an average shear strength value of 755,190 MPa, while the drill variation has an average shear strength value of 470,227 MPa. The average value for drill variations in the HAZ area was 185.06 while for the FSSW variation, it only reached 147.75. The macro test results proved that the cause of the shear strength in the FSSW was greater than that of the drill, this was caused by the difference in the size of the rivet diameter due to the use of a bad rivet gun. Meanwhile, based on the results of micro photos, the size of the structure in the HAZ area will be relatively longer than the RAW section, this is caused by friction between the tool and the workpiece

Study of Tensile and Impact Properties for 0<sup>0</sup> and 45<sup>0</sup> Fiber Directional Orientation of Polyester Resin Composites with Woven Ramie Reinforced

The current technological need is the use of eco-friendly and biodegradable composites. It seeks to increase the use of natural resources to engineer composite materials to be better than before. This study aims to analyze the effect of ramie fiber orientation for ramie composites (in this study 450 and 00) on tensile strength and impact strength and find the best orientation angle with higher power and impact value than the other fiber angles on ramie composite. The fiber used in this study was ramie fiber, and the matrix used was Yukalac 157 BQTN-EX polyester resin. This research method uses the experimental process of conducting experiments and testing. The results showed that the 00 angle direction composite achieved the highest average tensile strength value of 54.3 N/mm2, and the impact strength showed the highest average impact strength value of 0.0168 J/mm2, performed by the 00 composites.

The effects of impactor shape on the compression after impact strength of carbon/epoxy face sheet foam core sandwich structure

This study presents experimental results of compression after impact (CAI) strength testing of foam core sandwich structure with carbon/epoxy face sheets impacted at three different energies with either a blunt or sharp tip impactor. The impact energies used were chosen to span the barely visible impact damage (BVID) thresholds for the sharp (4.1 J) and blunt (12.9 J) impactors with an impact energy approximately halfway between these (8.1 J) also used. While most impact testing on composites utilize a hemispherical (blunt) impactor, actual damage to a part may be due to an object impacting the part that is not blunt, but sharp and the impact response and resulting CAI strength values may be different for a given impact energy level. In this study, with regards to the impact response, the sandwich specimens showed larger transverse displacements (by about a factor of two) during the impact event when impacted by a sharp impactor versus a blunt impactor. The maximum load of impact was larger for the blunt impactor by about a factor of three. The barely visible impact damage (BVID) threshold energy was lower by about a factor of three for the sharp impactor. The absorbed energy of impact was higher for the sharp impactor. The CAI strength results showed that the sharp impactor gave lower average CAI strength values at the lowest impact energy level used, slightly lower average CAI strength values for the medium impact energy used and about the same average CAI strength values for the highest impact energy used.

Assessment of Target Strength Value of Demersal Fish in Lancang Waters Using Simrad Single Beam Echosounder

Hydroacoustic technology is excellent at determining accurately and in near real-time the objects located near the seabed. Therefore, acoustic technology is widely recognized for fisheries resources mapping, including demersal fish. The objective of this study was to estimate the value of demersal fish target strength (TS) in the waters of Lancang Island, Kepulauan Seribu region. A Single Beam Echosounder Simrad EK-15 with a frequency of 200 kHz was employed for data collecting in the waters around Lancang Island. The integration layer width was set at 3 meters with a horizontal integration distance of 200 meters. The average target strength (TSc) values obtained from the integration cell ranged from -55.52 dB to -42 dB with an average of -50.30 dB. Furthermore, the seabed depth influenced the distribution of TSc values, with higher TSc values in deeper habitat locations.

Prospective analysis of grip strength and load distribution after surgical treatment of common diseases of the hand with novel's manugraphy® system.

Carpal tunnel syndrome, A1 annular pulley stenosis and Dupuytren's contracture are among the most common conditions of the hand. In this study, we investigated the impact of surgical procedure on hand grip strength and high-resolution spatial load distribution in individuals suffering from those diseases over a follow-up period of one year. In this prospective study, data of 9 patients with carpal tunnel syndrome, 12 patients with A1 annular pulley stenosis and 7 patients with Dupuytren's contracture were evaluated. Only patients with unilateral disease were included providing the contralateral hand as an intra-individual control. Grip strength was measured with cylindrical instruments in two different sizes with respect to the hand size of the patients. Maximum and average values of grip strength as well as spatial load distribution in each finger, thenar, hypothenar and palm were analyzed. Data of the affected patients were collected preoperatively and 6weeks, 6months and 1year postoperatively. Grip strength and spatial load distribution were compared preoperatively to postoperatively. In addition, DASH score, Levine score, 2-point discrimination and degree of flexion contracture were assessed. The patients with A1 annular pulley stenosis showed a significant increase in grip strength 6months and one year postoperatively. Patients with carpal tunnel syndrome and Dupuytren's contracture showed no significant difference in grip strength over the course of time. An increase in the percentual grip strength of the thenar in patients with carpal tunnel disease and within the affected finger in A1 annular pulley stenosis was observed over the course of time. The DASH score was significantly lower in all patient cohorts one year postoperatively. Surgical procedure in carpal tunnel syndrome, A1 annular ligament stenosis and Dupuytren's contracture improves the functionality of the hand in everyday life. Some areas of the hand seem to compensate other weaker areas in grip strength.

Cu-Cu Thermocompression Bonding with a Self-Assembled Monolayer as Oxidation Protection for 3D/2.5D System Integration.

Cu-Cu direct interconnects are highly desirable for the microelectronic industry as they allow for significant reductions in the size and spacing of microcontacts. The main challenge associated with using Cu is its tendency to rapidly oxidize in air. This research paper describes a method of Cu passivation using a self-assembled monolayer (SAM) to protect the surface against oxidation. However, this approach faces two main challenges: the degradation of the SAM at room temperature in the ambient atmosphere and the monolayer desorption technique prior to Cu-Cu bonding. In this paper, the systematic investigation of these challenges and their possible solutions are presented. The methods used in this study include thermocompression (TC) bonding, X-ray photoelectron spectroscopy (XPS), shear strength testing, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The results indicate nearly no Cu oxidation (4 at.%) for samples with SAM passivation in contrast to the bare Cu surface (27 at.%) after the storage at -18 °C in a conventional freezer for three weeks. Significant improvement was observed in the TC bonding with SAM after storage. The mean shear strength of the passivated samples reached 65.5 MPa without storage. The average shear strength values before and after the storage tests were 43% greater for samples with SAM than for the bare Cu surface. In conclusion, this study shows that Cu-Cu bonding technology can be improved by using SAM as an oxidation inhibitor, leading to a higher interconnect quality.

316L-toughened porous Al2O3-based ceramic functionally graded materials using binder jetting

Al2O3-based ceramic functionally graded materials (FGMs) containing 1 wt% CuO and 4 wt% TiO2 as sintering aids and 0–40 wt% 316L as a toughening phase are fabricated by binder jetting additive manufacturing, and the low-temperature co-sintering toughening mechanism was studied. According to the 3D Stereo Microscope and XRD results, the interfacial microstructure exhibited a noticeable gradient change after being sintered from 1200 °C to 1450 °C for 2 h, and the main phases were Al2O3, γ-austenitie, Fe3C and a small amount of δ-ferrite. The FGMs sintered at 1450 °C had maximum relative density, X–Z-axis dimensional shrinkage and average bending strength values of 70.05%, 4.89%, 10.15%, 17.53% and 26.9 ± 0.87 MPa, respectively. Bending cracks originated from the pure Al2O3-based ceramic layer and gradually propagated to the high-316L side, accompanied by the crack bridging and deflection phenomena. The maximum crack deflection degree was about 90° at 1200 °C and 1400 °C. Obviously, the existence of crack bridging and deflection illustrated that 316L addition effectively improves the toughness of FGMs.

Experimental Study on the Mechanical Properties and Acoustic Emission Characteristics of Different Bedding High-Rank Coals.

Bedding has an important influence on the macroscopic and microscopic mechanical properties of coal, and the mechanical properties of coal and rock mass and acoustic emission characteristics are very important for rock burst monitoring and warning. In order to explore the influence of different beddings on the mechanical properties and acoustic emission characteristics of high-rank coal, using the RMT-150B electrohydraulic servo rock mechanics test system and the DS5 acoustic emission analyzer, the uniaxial compression and acoustic emission characteristics of high-rank coals with different beddings (parallel bedding 0°, oblique bedding 30, 45, 60°, and vertical bedding 90°) were investigated. The results show that the uniaxial compressive strength and deformation modulus of vertical stratified coal samples are the largest, which are 28.924 MPa and 2.95 GPa, while the average values of uniaxial compressive strength and deformation modulus of oblique stratified coal samples are the smallest, which are 10.91 MPa and 1.776 GPa, respectively. With the increase of the bedding angle, the uniaxial compressive strength of high-rank coal decreases first and then increases. The stress-strain process of coal varies greatly with different high stratification grades (parallel bedding 0°, oblique bedding 30°, 45°, 60° and vertical bedding 90°). The loading times of parallel, oblique, and vertical beddings are 700, 450, 370, 550, and 600 s, and the acoustic emission mutation point values are 495, 449, 350, 300, and 410 s. The mutation point value can be used as precursor information to judge the failure of high-rank coal in different beddings. Research results to find the high-rank coal destruction instability prediction method and the index provide a basis; further damage to the acoustic emission testing high order coal provides reference significance; and the use of acoustic emission in the monitoring and early warning of percussive ground pressure, the bedding surface of coal, and the actual stress on site should be considered.

The effects of off-axis loading on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

This study presents experimental results of compression after impact (CAI) testing of aluminum honeycomb core sandwich structure with face sheets made of co-cured T1100/3960 quasi-isotropic carbon/epoxy when tested at +22.5⁰ and −22.5⁰ with respect to the 0⁰ fibers. In a previous study examining the CAI strengths of honeycomb sandwich structure, it was found that specimens had different CAI strengths, based on a [−45/90/+45/0]S layup, depending on whether they were tested in the 0⁰ direction (face sheet layup of [−45/90/+45/0]S) or 90⁰ direction (face sheet layup of [+45/0/-45/90]S). The CAI strength results showed that the specimens tested in the 90⁰ direction had a 19% drop in CAI strength compared to specimens tested in the 0⁰ direction. This was attributed to the 0⁰ load bearing plies in the 0⁰ direction specimens being “tucked in” at the center of the specimen thus providing more stability against microbuckling. This raised the question as to what CAI strength would specimens tested at +22.5⁰ (face sheet layup of [−22.5/−67.5/+67.6/+22.5]S) and −22.5⁰ (face sheet layup of [−67.5/+67.5/+22.5/-22.5]S) have compared to specimens tested in the 0⁰ and 90⁰ direction. Results presented in this study show that the specimens loaded at +22.5⁰ and −22.5⁰ have a similar average CAI strength compared to the specimens loaded in the 0⁰ direction. The specimens loaded in the 90⁰ direction exhibit 16% lower average CAI strength. Additional specimens were tested in the +45⁰ direction to put the 0⁰ load bearing fibers on the outside of the specimen to see if this would decrease the strength as has been documented for undamaged strength. These specimens have average CAI strength values between the 0⁰ direction average CAI strength values and the 90⁰ direction average CAI strength values.

Tensile Strength of Coconut Coir Fiber Composite as an Alternative Material to Replace Fiberglass in Hard Socket

Physically disabled is someone who has a movement system disorder or has physical abnormalities such as amputation, withering, stiffness, and others. The self-confidence of someone who has an amputee can be improved by having a prosthesis made, because it can replace the anatomical and functional functions of the body. The socket on the prosthesis is the most important component, because the use of the socket on the prosthesis is directly related to the patient's stump. One of the materials for making socket prosthesis is fiberglass. However, the use of fiberglass has a negative effect, namely it produces gas and dust emissions that can irritate stumps, is not a local product, and is difficult to recycle. Alternative fiber materials are using fibers from nature, coco fiber is an option as an alternative to fiberglass. The tensile strength test is the most basic test. The tensile strength test was carried out to determine the stress, strain, and elastic modulus of the fibrous polymer composites. The purpose of this study was to analyze and compare the tensile strength between fiberglass and coconut coir fiber, so as to find out which fiber material is suitable as an alternative to fiberglass in the manufacture of socket prosthesis. Using experimental quantitative methods. The composite material uses coconut coir fiber which was previously treated with 5% NaOH for 1 hour and then dried for 2-3 days. In the fabrication process using the vacuum bag method. Standard specimen refers to ASTM D3039/3039M. Tensile testing showed that the average tensile strength value of the coco fiber composite was 16.2 MPa and the average tensile strength value of the fiberglass composite was 30.2 MPa. This means that the value of the tensile strength of coco fiber is still below fiberglass and cannot be used as a substitute for fiberglass. However, coconut coir fiber can be used as an alternative to fiberglass, judging from the average maximum force that the coco fiber composite can withstand, which is 2630 N or equivalent to a load of 263 kg, this value is sufficient for the average adult weight in Indonesia with an average weight of 60 kg body

Periquiteira (Cochlospermum orinocense): A Promising Amazon Fiber for Application in Composite Materials.

Natural lignocellulosic fibers (NLFs) have in recent decades appeared as sustainable reinforcement alternatives to replace synthetic fibers in polymer composite material applications. In this work, for the first time, the periquiteira (Cochlospermum orinocense), a lesser known NLF from the Amazon region, was analyzed for its density and, by X-ray diffraction (XRD), to calculate the crystallinity index as well as the microfibrillar angle (MFA), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron analysis (SEM) and tensile strength. The apparent density found for the periquiteira fiber was 0.43 g/cm3, one of the NLF's lowest. XRD analysis indicated a crystallinity index of 70.49% and MFA of 7.32°. The TGA disclosed thermal stability up to 250 °C. The FTIR analysis indicated the presence of functional groups characteristic of NLFs. The SEM morphological analysis revealed that the periquiteira fiber presents fine bundles of fibrils and a rough surface throughout its entire length. The average strength value of the periquiteira fiber was found as 178 MPa. These preliminary results indicate that the periquiteira fiber has the potential to be used as a reinforcing agent in polymeric matrices and can generate a lightweight composite with excellent mechanical properties that can be used in various industrial sectors.

Frost-Resistant Rapid Hardening Concretes.

This article presents the results of research conducted to determine the possibility of accelerating strength gain and enhancing the operational reliability of concrete. The study tested the effects of modern modifiers on concrete in order to select the composition of rapid hardening concrete (RHC) with better frost resistance characteristics. A basic composition of RHC grade C 25/30 was developed using traditional concrete calculations. Based on the analysis of previous studies by other authors, two basic modifiers (microsilica and calcium chloride (CaCl2)) and a chemical additive (a hyperplasticizer based on polycarboxylate esters) were selected. Then, a working hypothesis was adopted to find optimal and effective combinations of these components in the concrete composition. In the course of experiments, the most effective combination of additives for obtaining the best RHC composition was deduced by modeling the average strength values of samples in the early ages of curing. Further, RHC samples were tested for frost resistance in an aggressive environment at the ages of 3, 7, 28, 90, and 180 days to determine operational reliability and durability. The test results showed a real possibility of accelerating concrete hardening by 50% at the age of 2 days and achieving up to 25% strength gain by using both microsilica and calcium chloride (CaCl2). The best frost resistance indicators were observed in the RHC compositions with microsilica replacing part of the cement. The frost resistance indicators also improved with an increase in the amount of microsilica.

Analisis Karakteristik Bahan Tembaga Akibat Pengaruh Proses Penempaan Terhadap Kekuatan Impak

Indonesia is one of the countries with the largest copper reserves in the world, namely the Tembagapura area, Mimika Regency, Papua Province. The development of electric car technology has a significant impact on increasing the demand for copper. This study conducted material engineering on copper materials with the forging process. The aim of the research was to obtain the average impact energy, average impact strength, and fracture shape of the material from a variety of copper materials. The variation of each test specimen was formed following the ASTM E23 standard with a size specification of 55 mmL x 10 mmW x 8 mmT. The experimental study of impact testing by the charpy method yielded an average impact energy value of 169.081 Joule and 98.058 Joule respectively for copper variations X 1 and X 2 . The average impact strength values produced by the copper variations X 1 and X 2 are 2.114 J/mm 2 and 1.226 J/mm 2 respectively. The results of physical observations of the two variations of the copper material show that the material is not broken with fibrous fractures. The data from the test results can be declared that the forging process with hot working has an effect on increasing material characteristics by 58% and copper materials are classified as ductile materials.

Influence of the number of layers on the strength of beech laminated elements in the three-point flexural test,

A chair is a piece of furniture whose elements are loaded with relatively high forces. The strength of these elements is vital for the safety of using this type of furniture. The research aims to test the chair material system made of beech wood. The authors analyzed laminated elements with 9, 11, and 13 layers of veneers. The veneers were 1.23 mm thick, with perpendicular fiber directions in adjacent layers, and bonded with 220 g/m2 of PVAc adhesive. The moisture content of the elements was 6 ± 1%. A three-point bending flexural test was performed to determine the stress-strain response of the tested three variants. A complementary numerical analysis allowed a more precise comparison of the three analyzed laminated elements variants. It was confirmed that all variants exceed the desired minimal values in chair support design. Moreover, the average strength values for tested laminated elements, differing in the number of veneers, were sufficient even with a reduced number of veneer layers. The experiments and numerical analysis results confirmed the usability of the three tested types of beech laminated elements to be used as highly loaded chair elements.

Application of Biogenic Mineral Formation for the Preservation of Limestone Masonry at the Eski-Kermen Archeological Site

Minimal interference with historical material and maximum preservation is one of the basic principles of the scientific restoration and conservation of monuments of historical and cultural heritage. The creation of nanoscale and microscale inorganic coatings is a promising way to protect limestone and marble cultural heritage objects. We conducted a laboratory testing of a method for stimulating biogenic mineral formation on the surface of limestone-masonry samples from the medieval cave town on the Eski-Kermen plateau (Crimea, Russia). The results showed the formation of a layer of crystallites of 0.4 to 1.3 µm on the surface of the limestone, an increase in the average strength values of the samples by 28% from 12.3 ± 2.8 to 15.8 ± 2.6 MPa, a 42% increase in the specific surface area of limestone, an 86% increase in salt attack resistance, and preservation of the capillary water-absorption level. The obtained results show the potential of using biogenic mineral formation for the conservation and restoration of limestone.