Fatigue Strength of Wood Under Pulsating Tension-Torsion Combined Loading

Fatigue strength of wood under cyclic tension-torsion combined loading was investigated experimentally. The material used for the experiments was a rectangular bar of Japanese cypress. Pulsating tension-torsion combined loadings were respectively applied along and around the longitudinal axis of the specimen, which coincided with the longitudinal direction of the wood. The obtained results of fatigue tests were found to be influenced by the combined-stress ratios and the applied stress levels, and were summarized as follows: 1) All data were located in a slightly wide band on the S-N plot in spite of different combined-stress ratios, but the slope of the S-N curves became low when tensile stress was dominant. 2) Failure modes of the test specimen depended on whether tensile or shear stress was dominant in the biaxial stress ratios. 3) Hill's criterion for the static strength was suitable for evaluating the fatigue strength under combined-stress ratios

Bending Fatigue of Wood: Strain Energy-Based Failure Criterion and Fatigue Life Prediction

In this study, bending fatigue behavior of Japanese cedar and Selangan batu was examined. A nonreversible triangular waveform with loading frequencies of 0.5 and 5 Hz was used as load. Applied loads were about 110-70% of the static strength. The fatigue life of Japanese cedar was found to be longer at 5 Hz, especially at low stress level. For Selangan batu, however, loading frequency did not affect fatigue life. When fatigue life exceeded about 40,000 cycles, a crack formed on the compressive sides of the specimens regardless of the loading frequency and species. Cumulative strain energy at failure was found to be the failure criterion regardless of the loading frequency. This criterion could be estimated using the strain energy through the static test. A fatigue life prediction method based on the strain energy of the second loading cycle was proposed. This prediction method provided a good prediction of fatigue life

Fatigue Damage in Wood Under Pulsating Multiaxial-Combined Loading

A fatigue test was performed under axial-torsion combined loading, with the aim of investigating fatigue damage in wood under multiaxial stresses. This research particularly focused on the energy loss captured during fatigue tests and the fatigue limit for wood. Air-dried samples of Japanese cypress were used for the tests. An electrohydraulic servomachine that could apply axial and torsional loads simultaneously was used for the fatigue tests. An axial load was applied in the fiber direction (along L), and torque was applied around the axis in the same direction as L. A pulsating triangular axial load was applied in the longitudinal direction at 1 Hz while each specimen was also simultaneously subjected to a twisting moment at the same phase. On the basis of the experimental results of the fatigue tests, energy loss was obtained from the stress-strain curve at each loading cycle and examined precisely in relation to the number of loading cycles and combined stress states. The energy loss per cycle in the dominant stress was large and increased gradually toward fatigue failure. The stress level was so high that the energy loss per cycle was extremely large. In the relationship between cumulative energy loss and the number of loading cycles, the cumulative energy loss was so large that the fatigue life was extremely long. The cumulative energy loss for shear in the compression group was larger than that in the tension group. The mean energy loss per cycle for the fatigue limit was also presumed from the relationships between mean energy loss per cycle, stress amplitude, and fatigue life, and was estimated to be about 10 kJ/m3/cycle, as determined on the basis of the equivalent stress principle. That is, the fatigue life will be infinite when the energy loss per cycle is below 10 kJ/m3/cycle

Fatigue Behavior in Wood Under Pulsating Compression-Torsion-Combined-Loading

We have experimentally investigated the effects of cyclic compression-torsion-combined loading on the fatigue behavior and stress-strain properties of wood. Pulsating compression and torsion loadings were applied along and around the longitudinal axis of the rectangular bar specimen (Japanese cypress). According to the relationships between stress and strain during fatigue tests, the secant modulus of the stress-strain curve changed with an increase in the number of loading cycles, and the differences between the curves for compression and shear were observed. We found that the experimental results of fatigue tests were influenced by the combined-stress ratios. Compressive stiffness tended to maintain its initial values during almost all loading cycles to failure. Shear stiffness decreased with increasing number of loading cycles, and the final decrease of shear stiffness was larger as compressive stress became dominant. The failure mode was affected by the combined stress states; typical torsion failure was observed in combined stress states with dominant application of shear stress. In contrast, typical compression failure was observed in combined stress states with dominant application of compressive stress. The failure mode under compressive-shear combined stress states was not affected by the stress level, although, as previously demonstrated, it was affected by the stress level under tensile-shear states

KONSTRUKSI TEORI LARAS KARAWITAN SUNDA : KAJIAN TENTANG LAHIRNYA LARAS SOROG BERDASARKAN ANALISIS STRUKTUR MUSIKALITAS

Penelitian ini dilatarbelakangi oleh adanya teori laras Kusumadinata yang diajarkan di sekolah, yaitu "pelog dan sorog adalah laras yang dilahirkan dari laras salendro (dari gamelan salendro)". Mengenai pelog, dalam penelitian terdahulu sudah menjadi jelas bahwa pelog adalah laras mandiri yang telah ada di Sunda sejak periode Hindu. Maka dalam penelitian ini menyelidiki mengenai lahirnya laras sorog, dengan bertujuan untuk menghasilkan teori laras baru. Penelitian ini menggunakan metode grounded theory approach dengan pendekatan etnomusikologis dan historis. Pengumpulan data dilakukan melalui partisipatori observasi, wawancara, studi dokumentasi, dan studi literature. Pertama, dianalisis fenomena pada gamelan salendro, yaitu melodi (rebab dan vokal) secara konvensional menjadi sorog. Kemudian, dianalisis fenomena serupa yang disebut 'barang miring' pada gamelan slendro Jawa, karena gamelan salendro Sunda adalah awalnya gamelan slendro Jawa dari Mataram. Kemudian, untuk mencari asal mulanya 'barang miring', diteliti nyanyian dalang pada wayang kulit purwa Jawa. Demikian juga untuk mencari asal mulanya laras sorog, diteliti nyanyian dalang pada wayang golek purwa Sunda. Kemudian, untuk menyelidiki proses sorog menjadi laras mandiri, disimak tembang Sunda Cianjuran dan gamelan degung. Hasil penelitian ini menunjukkan bahwa laras sorog di Sunda berasal dari nyanyian Semar berupa 'barang miring' yang dinyanyikan oleh dalang dalam penyajian wayang kulit purwa dari Jawa (Mataram). Kemudian fenomena 'barang miring' dari Jawa berkembang dalam proses perkembangan wayang golek purwa, dan menjadi laras mandiri dalam proses perkembangan tembang Sunda Cianjuran dan gamelan degung. Maka dapat dikatakan pula bahwa adanya laras sorog di Sunda adalah hasil kreativitas orang Sunda. Hasil penelitian ini memberi pengetahuan baru untuk etnomusikologi, juga memberi kontribusi positif untuk pendidikan seni.This study is motivated by the Kusumadinata's scale theory which has been taught in schools, that is "pelog and sorog are scales born from salendro (from gamelan salendro)". Regarding pelog, in previous studies it has become clear that the pelog has independently existed since the Hindu era. Hence, in this study investigates the origin of the sorog scale (laras sorog), with the aim of constructing a new scale theory. In this research, the grounded theory approach method is used with a ethnomusicological and historical approach. Data collection was carried out through participatory observations, interviews, documentation studies, and literature studies. First, I analyzed the phenomenon that occurs in the gamelan salendro performance, i.e., its melody (rebab and vocals) conventionally becomes sorog. Then, I analyzed a similar phenomenon in the Javanese gamelan slendro called 'barang miring', because the Sundanese gamelan salendro was originally a Javanese gamelan slendro from Mataram. Then, to find the origin of the 'barang miring', I analyzed the dalang's songs in the Javanese wayang kulit purwa. Likewise, to find the origin of the sorog, I analyzed the dalang's songs in the Sundanese wayang golek purwa. Then, to investigate the process of the sorog becoming an independent scale, I studied the tembang Sunda Cianjuran and gamelan degung. The results of this study indicate that the origin of the sorog scale is Semar's song ('barang miring') in the Javanese wayang kulit purw. Then the phenomenon called 'barang miring' develops in the process of development of the Sundanese wayang golek purwa, and became an independent scale in the process of development of tembang Sunda Cianjuran and gamelan degung. Therfore it can be said that the existence of the sorog scale in Sunda is the result of the creativity of the Sundanese. The implication of this study provide new knowledge for ethnomusicology, and make a positive contribution to arts education

THEORETICAL ESTIMATION OF MECHANICAL PROPERTIES OF PLYWOOD-SHEATHED SHEAR WALL WITH COMBINED USE OF ADHESIVE TAPE AND WOOD DOWELS

Shear walls often function as elements that provide resistance to horizontal external forces exerted on wooden frames. Many shear walls with superior strength performance have been developed for this purpose. Amidst this backdrop, we have attempted to develop a shear wall that, in addition to strength performance, decreases the time and labor required for disposal. More specifically, the authors proposed a novel “metalless” shear wall: a shear wall in which industrial double-sided adhesive tape is used to attach plywood to the framework. Also, wood dowels are used as supplementary connectors with the aim of enhancing strength performance. Unlike conventional shear walls that use nails and metal fixtures, separation at the time of disposal is unnecessary, and therefore, disposal time and labor of the wall are anticipated to be significantly decreased. Thus, this study involved demonstrating and verifying a methodof theoretical analysis for the mechanical performance of these kinds of shear walls toward in-plane shear force. Specifically, this study derived a method to estimate the mechanical behavior (load-deformation angle relationship) of plywood-sheathed shear walls based on shear performance obtained from double shear tests of joint specimens with the combined use of adhesive tape and wood dowels. Also, the validity of the method was experimentally verified. The results showed that the method proposed in this study was able to estimate the mechanical behavior and mechanical properties of the newly proposed shear wall, and the validity of the method was confirmed

ENERGETICS APPROACH TO FATIGUE BEHAVIOR OF WOODEN JOINT USING DOUBLE-SIDED ADHESIVE TAPE

The authors have previously studied the possibility of the use of industrial double-sided adhesive tape as a method for jointing wooden panel to wooden framework. The mechanical performance of joints formed by such methods is comparable to that of nailed joint under static load conditions. However, the mechanical performance of such joints has not been evaluated under cyclic load conditions. This study was conducted to investigate this aspect of their performance. Double-shear specimens were prepared by bonding wooden panel to wooden framework using two types of adhesive tape with different substrates. Specimens were also prepared with wooden dowels to strengthen their jointing performance. The joint specimens were subjected to cyclic shear loading testing. The results of the tests were analyzed from an energetics perspective, and the shear deformability of the specimens at failure was estimated. The test results indicate that both the specimens formed using adhesive tape and those formed using wooden dowels had fatigue properties comparable to nailed joint specimens. A tendency for the shear deformability caused by cyclic loading to increase with the stress level was observed. It was possible to estimate the shear deformability by evaluating the energy absorption capacity of the joints from an energetics standpoint

Neuroprotective Effects of Lutein in the Retina

Although a large variety of pharmaceutical therapies for treating disease have been developed in recent years, there has been little progress in disease prevention. In particular, the protection of neural tissue is essential, because it is hardly regenerated. The use of nutraceuticals for maintaining the health has been supported by several clinical studies, including cross-sectional and interventional studies for age-related macular disease. However, mechanistic evidence for their effects at the molecular level has been very limited. In this review, we focus on lutein, which is a xanthophyll type of carotenoid. Lutein is not synthesized in mammals, and must be obtained from the diet. It is delivered to the retina, and in humans, it is concentrated in the macula. Here, we describe the neuroprotective effects of lutein and their underlying molecular mechanisms in animal models of vision-threatening diseases, such as innate retinal inflammation, diabetic retinopathy, and light-induced retinal degeneration. In lutein-treated mouse ocular disease models, oxidative stress in the retina is reduced, and its downstream pathological signals are inhibited. Furthermore, degradation of the functional proteins, rhodopsin (a visual substance) and synaptophysin (a synaptic vesicle protein also influenced in other neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease), the depletion of brain-derived neurotrophic factor (BDNF), and DNA damage are prevented by lutein, which preserves visual function. We discuss the possibility of using lutein, an antioxidant, as a neuroprotective treatment for humans

Neural Degeneration in the Retina of the Streptozotocin-Induced Type 1 Diabetes Model

Diabetic retinopathy, a vision-threatening disease, has been regarded as a vascular disorder. However, impaired oscillatory potentials (OPs) in the electroretinogram (ERG) and visual dysfunction are recorded before severe vascular lesions appear. Here, we review the molecular mechanisms underlying the retinal neural degeneration observed in the streptozotocin-(STZ-) induced type 1 diabetes model. The renin-angiotensin system (RAS) and reactive oxygen species (ROS) both cause OP impairment and reduced levels of synaptophysin, a synaptic vesicle protein for neurotransmitter release, most likely through excessive protein degradation by the ubiquitin-proteasome system. ROS also decrease brain-derived neurotrophic factor (BDNF) and inner retinal neuronal cells. The influence of both RAS and ROS on synaptophysin suggests that RAS-ROS crosstalk occurs in the diabetic retina. Therefore, suppressors of RAS or ROS, such as angiotensin II type 1 receptor blockers or the antioxidant lutein, respectively, are potential candidates for neuroprotective and preventive therapies to improve the visual prognosis

Mechanism Underlying IKK Activation Mediated by the Linear Ubiquitin Chain Assembly Complex (LUBAC)

The linear ubiquitin chain assembly complex (LUBAC) ligase, consisting of HOIL-1L, HOIP, and SHARPIN, specifically generates linear polyubiquitin chains. LUBAC-mediated linear polyubiquitination has been implicated in NF-κB activation. NEMO, a component of the IκB kinase (IKK) complex, is a substrate of LUBAC, but the precise molecular mechanism underlying linear chain-mediated NF-κB activation has not been fully elucidated. Here, we demonstrate that linearly polyubiquitinated NEMO activates IKK more potently than unanchored linear chains. In mutational analyses based on the crystal structure of the complex between the HOIP NZF1 and NEMO CC2-LZ domains, which are involved in the HOIP-NEMO interaction, NEMO mutations that impaired linear ubiquitin recognition activity and prevented recognition by LUBAC synergistically suppressed signal-induced NF-κB activation. HOIP NZF1 bound to NEMO and ubiquitin simultaneously, and HOIP NZF1 mutants defective in interaction with either NEMO or ubiquitin could not restore signal-induced NF-κB activation. Furthermore, linear chain-mediated activation of IKK2 involved homotypic interaction of the IKK2 kinase domain. Collectively, these results demonstrate that linear polyubiquitination of NEMO plays crucial roles in IKK activation and that this modification involves the HOIP NZF1 domain and recognition of NEMO-conjugated linear ubiquitin chains by NEMO on another IKK complex