Measurement and analysis of truck transport vibration levels and damage to packaged tangerines during transit

The purpose of this study was to measure the vibration levels in commercial truck shipments in Thailand and observe the effects on packaged fruit. The study measured the vibration levels in two of the most commonly used truck types to ship packaged goods as a function of road condition and vehicle speed. The suspension type on the trailers studied was leaf‐spring. The results of damage to packaged tangerine fruit as a function of location in the payload are also presented. The data presented in this study will assist product and package designers to reduce damage in transit. The results showed that vibration levels increased with speed and as a result of road condition. Analysis of variance indicated that three controlling factors, road surface, truck speed and truck type, significantly affected (p ≤ 0.05) peak PSD, PSD* (root mean square) over the frequency range 2–5 Hz, and fruit damage. As expected, based on previous work, an increase in truck speed resulted in an increase in vibration levels and damage to packaged fruit. The laterite road condition produced the highest vibration level for a given truck and travelling speed followed by concrete highway and asphalt road conditions. Fruit damage was found to be greatest in the uppermost container for every combination of road, truck type and travelling speed, which also corresponded to the highest vibration levels recorded. The results showed that a significant amount of damage can occur on unpaved roads (laterite), while the packages are transported from farms and harvesting areas to regional truck terminals. Damage on asphalt road conditions was minimal. This paper provides an updated history of measured and quantified levels of vibration for these specific trucks and road conditions. Copyright © 2005 John Wiley & Sons, Ltd.     

Measurement and analysis of truck and rail vibration levels in Thailand

Worldwide increase in trade, foreign direct investment, capital flows, migration and the spread of technology has caused an increased focus to be put on designing packages that can protect goods shipped globally. This requires a wide‐ranging understanding of the distribution environments on a global basis. Several past studies have mapped the vibration levels for surface transportation along the most popular shipment routes in countries such as Brazil, Canada, China, India and the USA. This study was conducted to provide a comprehensive understanding of the vibration levels observed for truck and rail shipments for major transportation routes in Thailand, one of the leading economies in the Southeast Asia region. Data recorders were used to collect the vibration data which were then analysed in terms of power spectral densities. Vibration levels observed from various segments of transportation are presented in the form of power density spectrums. Composite spectrums that can be used to simulate the measured vibration conditions in Thailand are presented. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of vehicle speed on shock and vibration levels in truck transport

An update on the nature of shock and vibration in truck transport was obtained by measuring and analysing the shock and vibration levels separately that occur during truck transportation in Japan. The effect of truck speed on the shock and vibration levels was mainly analysed. A significant difference was observed between the acceleration of vibration, and the acceleration including shock and vibration as a result of truck speed. The results indicated that the effect of truck speed on root mean square acceleration (Grms), including shock and vibration, was strong at a lower speed, but slight at a higher speed. The highest Grms, including shock and vibration, was found at 45–59.9 km/h on local roads, which was higher than that during highway driving. When the speed was below 45 km/h, the peak power spectral density (PSD) of acceleration including shock and vibration increased as truck speed increased; when the speed was above 45 km/h, no significant changes in peak PSD were found because of truck speed. At the same time, the effect of vehicle speed on the vibration acceleration was also studied. It was found that the higher the vehicle speed, the higher the Grms and peak PSD value of vibration in both the vertical and lateral directions. Copyright © 2010 John Wiley & Sons, Ltd.     

Measurement and analysis of truck and rail shipping environment in India

Free trade agreements have been on the rise in all regions of the world in the past decade. This has allowed for global distribution and marketing of products in an international market. Products once produced for domestic markets must now be able to compete in international markets without trade barriers. Increased international commerce and manufacturing have forced many packaging and logistics engineers to broaden their true understanding of the global distribution environment. India is a recent entrant on the global arena for manufacturing and services. While China's economic developments have dominated global headlines, India's own growth has been impressive as well, with a gross domestic product rising 5% per annum on average since 1990. India is hence primed to follow China as the next low‐cost manufacturing super power. With an increasing interest from multinational corporations in conducting commerce with India, there arises a great need to understand the conditions of the transportation infrastructure there to promote logistical understanding of the distribution environments. This paper provides a brief overview of the road and rail transportation environment in India. It also provides the results of a 2 year study that measured and analysed truck and rail transport vibration for the major freight distribution routes between New Delhi, Bangalore, Mumbai, Chennai, Hyderabad and Kolkatta. Copyright © 2007 John Wiley & Sons, Ltd.     

箱装苹果振动特性及损伤的试验研究

振动损伤是引起果品采后损耗的主要因素之一,研究振动强度、缓冲包装结构等因素对果品振动损伤的影响对控制和降低果品运输损伤具有重要意义.以正交试验为基础,研究了振动强度、缓冲包装结构和包装箱内果品放置层数这3个因素对苹果损伤率与果品振动传递率的影响,并用新的试验手段得到了振动工况下箱内各层果品的加速度变化情况.结果表明,3个因素对苹果损伤率和果品振动传递率均有影响,其中振动强度对其影响最为显著,缓冲包装结构、箱内果品放置层数的重要性依次减小;振动试验条件下,箱内各层苹果的加速度由下向上逐渐增加;不同试验条件下果品振动传递率不同,振动传递率越小,苹果损伤率越低.     

混凝土泵车臂架振动响应的主动控制实验研究

考虑混凝土泵车臂架结构特点,采用独立模态空间控制方法对泵送混凝土激励下的臂架末臂节振动响应进行了主动控制试验研究。针对泵车臂架系统的动力学模型,采用模态滤波技术和最优控制理论设计主动控制策略,通过优选臂节油缸的作动控制以实现对臂架一阶模态振动响应的实时控制。实验结果表明,采用该主动减振控制后水平工况下臂架末端的减振精度可达80%,取得了显著的减振实验效果     

Measurement and analysis of US truck vibration for leaf spring and air ride suspensions,and development of tests to simulate these conditions

There is a significant amount of goods that are transported using tractor trailers. Most high‐value products, such as electronics, highly perishable goods like fruits and vegetables and most retail consumer products, are shipped using trucks in North America. It is therefore important to measure and quantify the levels of vibration that occur inside this mode of transport as it pertains to damage. Vibration levels inside a tractor‐trailer are a function of the road surface, the speed of the vehicle, the type of suspension and the structure of the trailer. The purpose of this study was to determine the levels of vibration as a function of trailer suspension at normal operating speeds in commercially used truck equipment, over 16000km of road surfaces in North America. Copyright © 2006 John Wiley & Sons, Ltd.     

Effects of reduced pressure and vibration on haz‐mat packages for liquids

Eleven different bottle/closure systems used to package dangerous goods for transportation by air were tested for leakage. The bottles were filled with water and subjected to the combined effects of random vibration and external pressure equivalent to an altitude of 14000ft (4267m) for up to an hour. The bottles were placed in the vertical, horizontal and inverted orientations and observed for leaks. The differences in bottle weights before and after the tests were used to quantify leakage. The results show that of the 11 package types tested, six leaked when subjected to simulation of the air transport environment. Those systems utilizing ‘stretch tape’ around the closure did not leak. Copyright © 2006 John Wiley & Sons, Ltd.     

Measurement and analysis of truck transport environment in Brazil

Increasing trade in today's global economy requires packaging to be designed to contain, protect and deliver products without damage during transportation and handling. Vibration forces that occur during transportation are one of the most significant causes of damage during shipping. The objective of this study was to quantify and analyse the vibration that occurs during truck transport in Brazil. The study was done using two types of trucks: small local trucks for local metropolitan distribution areas and larger tractor‐trailers for cross‐country transportation. Ten metropolitan areas in different regions of Brazil were selected for 1‐day trips representing normal delivery. These trips encountered varying road surfaces (asphalt, concrete, stone and dirt). The long distance trips were done on highways that were more than 1200 km long. The vertical vibration levels were higher than the lateral and longitudinal levels as expected. A composite power density spectrum of all trips is provided in this paper to simulate truck transport in Brazil using random vibration test methods. Copyright © 2007 John Wiley & Sons, Ltd.     

Integral approach for optimizing modified atmosphere packages for elstar apples: A combination of product and packaging constraints

Modified atmosphere packages with Elstar apples in various packaging systems have been investigated. Loss of firmness during shelf-life is used as the quality aspect to judge the performance of the modified atmosphere packages. A system-oriented model is derived that describes the experimentally found concentrations well. In the overall approach the time dependency of the oxygen and carbon-dioxide concentrations are discussed. It is shown that the quality attribute, the softening of apples, can be affected by the choice of packaging material. Hence this approach can be used to optimize modified atmosphere packaging of Elstar apples.     

Fatigue failure of pb-free electronic packages under random vibration loads

The electronic equipment are used in several fields like, automotive, aerospace, consumer goods where they are subjected to vibration loads leading to failure of solder joints used in these equipment. This paper presents a methodology to predict the fatigue life of Pb-free surface mounted BGA packages subjected to random vibrations. The dynamic characteristics of the PCB, such as the natural frequencies, mode shapes and damping ratios were determined. Spectrum analysis was used to determine the stress response of the critical solder joint and the cumulative fatigue damage accumulated by the solder joint for a specific duration was determined.     

地铁隧道内不同轨道结构振动测试与分析

通过对地铁隧道内普通整体道床、Ⅲ型轨道减振器、弹性短轨枕、梯形轨枕、钢弹簧浮置板道床的现场振动测试,进行时、频域对比,了解各种减振措施在不同频率范围内的减振效果差异。结果表明,轨道减振器、梯形轨枕、弹性短轨枕及钢弹簧浮置板可分别降低隧道壁VLZmax分别为4 dB,7.6 dB,7.8 dB,19.0 dB;无论何种轨道减振措施,高频减振效果高于低频减振效果, Z计权的振动加速度级明显小于不计权的振动加速度级减振效果;梯形轨枕、弹性短轨枕、轨道减振器对50 Hz以上振动减振效果明显,钢弹簧浮置板道床对12.5 Hz以上振动减振效果明显,对控制列车运行产生的二次噪声更有效。     

Comparison between lateral,longitudinal, and vertical vibration levels in commercial truck shipments

The widespread use of tractor trailers for the shipment of packaged products has brought about the need to be able to quantify accurately the nature of the shipping environment as it pertains to damage. The purpose of this study was to compare the levels of lateral and longitudinal vibration to vertical levels measured in the same truck trailer travelling over the average USA highway. Four truck-trailer shipments, two with light loads and two with heavy loads, were instrumented with accelerometers and recording equipment. From the data acquired, power spectral density plots were developed. The results showed that below 20 Hz, lateral and longitudinal vibration levels were generally much lower than vertical levels, but at frequencies above 20 Hz, all three were similar. The more heavily loaded trucks showed higher lateral and longitudinal levels of vibration than the lightly loaded ones.     

Monitoring the Evolution of Damage in Packaging Systems under Sustained Random Loads

The ability of protective packaging systems to withstand dynamic loads during transportation is an important consideration when it comes to selecting a suitable material. The performance characteristics of packaging systems are best determined by subjecting the systems (such as cushioning materials and containers) to sustained random loads under controlled conditions. It is during these fatigue endurance tests that the loss of structural integrity of a material or an element needs to be quantified. The research presented herein uses two recently developed continuous structural integrity assessment techniques to evaluate variations in the mechanical properties (namely stiffness) of typical packaging elements. The first technique is based on the short‐time Fourier transform, and the other uses an adaptive digital finite impulse response (FIR) filter technique developed by the authors. The effectiveness and the limitations of the techniques were evaluated by undertaking selected controlled experiments during which damage was simulated by varying the length of a single degree‐of‐freedom vibratory system subjected to random base excitation. The materials used for the controlled experiments include steel, aluminium, acrylic and carbon fibre. Results show that, although both methods are capable of identifying the level of damage and the time at which it occurs, the FIR technique is generally more sensitive and better able to detect small changes in stiffness. Finally, the ability of integrity assessment techniques to monitor the progression of damage in real packaging elements, such as biodegradable air cushions and corrugated paperboard containers, was established. The analysis of real protective packaging elements subjected to random loads using both structural integrity assessment techniques yielded positive results. Generally, the adaptive FIR technique was found to be more sensitive in detecting small changes in system characteristics, even when the estimates were obtained with relatively coarse temporal resolution. Overall, the results presented in this study indicate that the adaptive FIR technique can be a practical and effective tool for establishing the ability of materials and structures to withstand sustained random loads. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of large truck crash severity using heteroskedastic ordered probit models

Long-combination vehicles (LCVs) have significant potential to increase economic productivity for shippers and carriers by decreasing the number of truck trips, thus reducing costs. However, size and weight regulations, triggered by safety concerns and, in some cases, infrastructure investment concerns, have prevented large-scale adoption of such vehicles. Information on actual crash performance is needed. To this end, this work uses standard and heteroskedastic ordered probit models, along with the United States’ Large Truck Crash Causation Study, General Estimates System, and Vehicle Inventory and Use Survey data sets, to study the impact of vehicle, occupant, driver, and environmental characteristics on injury outcomes for those involved in crashes with heavy-duty trucks. Results suggest that the likelihood of fatalities and severe injury is estimated to rise with the number of trailers, but fall with the truck length and gross vehicle weight rating (GVWR). While findings suggest that fatality likelihood for two-trailer LCVs is higher than that of single-trailer non-LCVs and other trucks, controlling for exposure risk suggest that total crash costs of LCVs are lower (per vehicle-mile traveled) than those of other trucks.     

Vibration damage rate curves for quantifying abrasion of printed packaging in accelerated random vibration test

Some vibration‐based damages in packaged products, such as surface abrasion and bruising of fruits, are not necessarily caused by vibration stresses at resonant frequencies. They are often nonfatigue damages resulting from the accumulation of low stress vibrations. This study introduces a new concept and methodology of vibration damage rate curves, which describes the relationship between damage rate, G_rms, and vibration cycles, N. The vibration damage rate curves for quantifying the abrasion of a column stacked printed packaging was developed on the basis of ASTM D 4169 truck profile level 1, 2, and 3, as well as the field test. The abrasion rate in the laboratory was then compared to that in the equivalent time of road transportation per accelerated random vibration test formula. This study recommends that the accelerated random vibration formula can be used when vibration damage rate curves for printed packaged products are developed, to effectively reproduce the damage in the laboratory that is equivalent to the field.     

Application of continuum damage mechanics to vibration fatigue life prediction

It is pivotal to predict the multiaxial vibration fatigue life during mechanical structural dynamics design. An algorithm of the finite element method implementation for multiaxial high cycle fatigue life evaluation is proposed, on the basis of elastic evolution model of continuum damage mechanics. By considering structural dynamic characteristics, namely, resonant frequencies and mode shapes, this algorithm includes a modal analysis and harmonic analysis, which makes this different from existing fatigue life prediction methods. A 10% decrease in the resonant frequency is regarded as the failure criterion. A critical damage value was obtained, which indicates mesocrack initiation fulfilment. To validate the effectiveness of the algorithm, auto‐phase sine resonance track‐and‐dwell experiments were conducted on notched cantilever beams made of Ti‐6Al‐4V alloy. The life predictions are conservative and in good agreements with the experimental results, which are mainly distributed within a scatter band of 2. This investigation could provide technical support for structural dynamics design and the analysis of reusable spacecraft.     

基于随机振动响应互相关函数的结构损伤识别试验分析

提出了基于结构振动响应互相关函数分析的损伤识别方法。通过八层剪切型钢框架结构模型在模拟白噪声随机激励作用下的试验分析,利用相邻测点响应的互相关函数幅值向量变化,构造损伤识别因子进行结构损伤判定、定位及程度量化,结果表明该方法对结构损伤的识别具有很好的简易性及有效性,并为结构在线监测和分散式检测提供方法参考。